Source: Wikimedia Commons

In the article “Proper Running Form: Does Gravity Help You Run Faster?”, we considered the importance of hip extension in running and noted that in cases of runners with restricted mobility in the front of the hips (e.g. tight Quads and/or Psoas), we often see a forward drop of the pelvis, highlighted by an increase in the curve of the lower back.

In other words, the body succeeds in traveling over the supporting leg, but without making optimum use of the powerful Gluteus maximus (the main muscle of the buttock).

As a result, stride length becomes compromised, propulsion is reduced, overall effectiveness of the running gait cycle is inhibited and risk of injury potentially raised.

This week’s article focuses on a smaller but equally important member of the glute family – the Gluteus medius.

What is the Gluteus medius and why is it important

As can be seen in the image to the right (posterior view), the Gluteus medius originates at the dorsal ilium (uppermost, largest bone of the pelvis) below the iliac crest and inserts at the top outside surfaces of the greater trochanter (top of the thigh bone).

It is the major abductor of the thigh (moves the leg away from the midline of the body). The anterior fibres rotate the hip internally and the posterior fibres rotate the hip externally.

Whilst the Gluteus maximus is a hip extensor (moves your leg behind you) and involved in the forwards & backwards tilting of the pelvis (dynamic stabilization in the sagittal plane), the Glute medius is a hip abductor (moves the leg out to the side) and as we shall see shortly plays a major role in controlling the sideways tilting of the pelvis, i.e. the sides of the hips rising & falling (dynamic stabilization in the frontal plane).

The Trendelenburg gait, named after Friedrich Trendelenburg’s studies on abnormal walking patterns in 1895, is exhibited by a person who through weakness in the abductor muscles cannot maintain sufficient height of the opposite side of the pelvis to raise the foot and transfer weight to the other leg. Instead, the pelvis drops downwards, meaning the affected person has to bend their leg more than usual at the knee in order to make up for the lack of lift.

To compensate, the stride on the unaffected side typically becomes shorter, along with a tendency for the person to lurch towards the weakened side in an attempt to maintain a level pelvis.

The hip drop

In the diagram below, the drawings (A) and (B) illustrate a runner in left leg “swing phase”, i.e. the left leg is off the ground and in the process of travelling forwards. The right leg is in mid-stance directly under the hips and taking maximum load as the body weight passes over it.

The Gluteus medius is highlighted as the dark area on the right hip. Here’s the difference: in image (A), the Gluteus medius is performing its role of dynamically stabilizing the pelvis such that the left hip does not drop more than 5 degrees (the image shows a straight line but in reality 4-5 degrees is regarded as the range necessary for minimizing vertical displacement of the body’s centre of gravity).

However, image (B) shows a weaker Gluteus medius not fulfilling its role and in effect allowing a marked drop (more than 5 degrees) of the left hip. The photo to the right of the drawings shows this same scenario for a real life runner.

Implications of a weak Gluteus medius

Various studies have shown a link between Gluteus medius weakness and athletic injury.

• In a study by Fredericson et al (2000), 24 distance runners with Iliotibial Band Syndrome had the hip abductor strength of their injured limb compared to that of the non injured limb (and to that of a control group). It was found that on average Gluteus medius strength was 2% less on the injured side.

• After a six-week rehabilitation period with particular focus on strengthening the Gluteus medius (side-lying hip abduction and pelvic drops), 22 of the 24 injured athletes were pain-free and able to return to running. Furthermore, a six-month follow-up showed no reports of recurrence.

• Other studies have also linked weaker hip abductors and external rotators to Patellofemoral Pain Syndrome (Ireland et al.,2003; Robinson et al.,2007; Cichanowski et al.,2007).

Strengthening the Gluteus medius

Given the body’s remarkable ability to find and adopt a compensatory movement pattern when faced with weakness or dysfunction, it is very important to use a gradual, progressive exercise program when attempting to strengthen and stimulate use of a weak muscle/muscle group.

Though in recent years much attention has been given to the importance of “functional” exercise (i.e. one that mimics as much as possible the dynamic movement we are aiming to achieve), experience shows that giving the body too complex a movement pattern too soon can often hinder or prevent recruitment of the target muscle/muscle group.

Studies that quantify the electromyographic activity (EMG) of the Gluteus medius during common therapeutic rehabilitation also seem to support the use of exercises that some would dismiss as not “functional” enough. In the table below, collated values are shown for exercises that scored significantly in three such studies: Bolgla et al.,(2004), DiStefano et al.,(2009) and Boren et al.,(2011).

Other studies have been done including research for exercises not included in the three studies above (Ayotte et al.,2007; Krause et al.’2009; Philippon et al., 2011) but none of them weaken the relevance of the data in the table. It is worth pointing out that the variance in results may be due to the technique used in execution of each exercise.

Also, which exercise/s you do will depend on your individual circumstances, needs and goals, all of which should be considered by a professional before you start a new program.

For example, although single-leg squats score the highest MVIC% in the table, they may not be appropriate for you at this moment in time if you are suffering from a particular knee condition.

All exercises can and should be regressed/progressed according to your personal fitness level. As always, if in any doubt, consult a suitably qualified health professional.

So, for the purpose of this article (and not as a prescribed exercise routine), we will now take a look at the five exercises listed in the table. The number of repetitions, sets, tempo and breathing patterns given serve as examples only and may well need modifying to suit individual needs & goals.

Single-leg squat

There is rarely ever just one way to perform an exercise. The method of execution will often vary according to what you are trying to achieve. In order to maximise use of the Gluteus medius (and indeed the whole of the Glute family), I personally encourage single leg squats that involve moving the centre of gravity backwards as opposed to forwards. In this case:

• The exercise is initiated by moving your backside backwards and downwards, as opposed to moving the knee of your supporting leg forwards. This can be challenging for many people as it requires a certain level of balance, coordination and flexibility.
• For this reason, the single-leg squat is often placed higher up on the ladder of exercise progression. Attempting it too early will often mean you resorting to moving your knee forwards, which in my opinion reduces recruitment of the glute muscles and puts more stress on the quadriceps muscles and knees.
• In order to encourage initiation of the exercise with a backwards shift, I often recommend clients place a suitably heighted chair behind them to give them a target and confidence in the fact that if they do lose stability they will not be falling onto a hard floor.
• If you are moving backwards, the natural position for the non-weight bearing leg will be in front of you as opposed to behind (see photo).
• As your strength and balance improves, you can progress by lowering the height of the object behind you.
• Whilst the edge of your bed may be a good place to start, it may well not be long until you are using the seat of the toilet as your goal.

Number of repetitions: 10-20 each leg
Number of sets: 1 on weaker leg (if applicable), 1 on stronger leg, 1 again on weaker leg.
Tempo: 3 seconds down (breath in), 1 up (breath out), 2 hold (keep breathing out)

Side-lying hip abduction

To work the right hip abductor muscles (as in the photo):

• Lie down in a left side-lying position. Make sure your hips are “stacked” (right hip directly over the left hip) and that your body is in a straight line.
• Placing your top hand on the floor in front of you can help ensure that you are not leaning forwards.
• Your pelvis should be in a neutral position (not hitched or tilted forwards/backwards).
• Though performance tempo can vary according to the goal, I typically have a client move accelerate when moving away from gravity, and decelerate when moving in the same direction as gravity.
• In the case of this exercise therefore, I would take 1 second to lift the top leg up (breathing out), 2 seconds to hold it in top position (keep breathing out) and then 3 seconds to slowly return it to start position (slowly breathing in).
• The position of the heel can be varied according to goals, but as a starter I typically encourage the heel to remain the same height as the toes throughout.

Number of repetitions: 15-25 each leg
Number of sets: 1 with weaker side (if applicable), 1 with stronger side, 1 again with weaker side.
Tempo: 1 up (breath out), 2 hold (keep breathing out), 3 down (breath in)

Single-leg deadlift

The single-leg deadlift can be performed in various ways but essentially your aim is to hinge forwards and reach your hands towards the ground whilst keeping your shoulders back, your back straight, and your supporting leg as straight as possible.

• From here you return back up and then repeat. In some versions of this exercise, the non-weight bearing leg is lifted to become as close as parallel to the ground as possible. (I kind of wish I had done this now in the photo – would have looked far more impressive!).
• Progression can involve using weights and/or performing the exercise on a less stable surface. Rotation is also often added to help encourage alignment of the hips.

As well as strengthening the Glutes, single-leg deadlifts can also be an excellent exercise for the hamstrings.

Number of repetitions: 10-20 each leg
Number of sets: 1 on weaker leg (if applicable), 1 on stronger leg, 1 again on weaker leg.
Tempo: 3 seconds down (breath in), 1 up (breath out), 2 hold (keep breathing out)

The hip drop

Hip drops, also referred to as pelvic drops, in effect mimic the hip drop we saw can happen during running if the Gluteus medius is not functioning optimally.

• Throughout this exercise, the supporting leg needs to remain straight as all movement needs to be a product of lifting and lowering the hip on the opposite side.
• The body will typically “cheat” on the way down by bending the supporting knee (instead of lowering the opposite hip) and “cheat” on the way up by raising the shoulder (instead of lifting the hip).
• As is the case in all the exercises, try to avoid allowing the pelvis to rotate forwards or backwards.

All exercises typically require quality of movement to achieve goals but this exercise in particular often falls prey to the body finding alternative ways to getting the job done.

Number of repetitions: 15-25 each leg
Number of sets: 1 on weaker leg (if applicable), 1 on stronger leg, 1 again on weaker leg.
Tempo: 2 seconds down (breath in), 2 up (breath out), 2 hold (keep breathing out)

The clam

The Clam is typically slandered by advocates of “functional training” but as we have seen research does show they should be considered depending on the needs of the client. I also find them a wonderful way to discover strength imbalances between the two hips.

• In side-lying position, slide your bent legs forward so that your hips are flexed to approximately 30 degrees (other versions of the exercise use different angles).
• Making sure your hips are “stacked” and (apart from your knees) the rest of your body is in a straight line, open your knees while keeping your heels together and pelvis in a neutral position (not hitched or tilted forwards/backwards).
• Placing your hand on the side of the hip should help you feel the Gluteus Medius contracting as the legs open.

Number of repetitions: 15-25 each leg
Number of sets: 1 with weaker side (if applicable), 1 with stronger side, 1 again with weaker side.
Tempo: 1 up (breath out), 2 hold (keep breathing out), 3 down (breath in)

Closing thoughts

I will finish by reiterating that selection of exercise needs to be based on factors, hence the need for therapists & trainers to treat the body in front of them as opposed to what they have read in a book.

As a performer of exercise, it is vital to follow a progressive program and take time to listen to the body. The research we have looked at does serve to remind us, however, that in a world where information is so quickly gained & shared, many exercises being prescribed today do run the risk of being too complicated.

The five exercises we have looked at should not be overlooked because of their age or simplicity. All the evidence suggests that the hip abductors play a very important role in running performance and injury avoidance, so if you need somewhere to start, the lonely Clam may not be such a bad idea!

Happy running!

Matt Phillips is a Run Conditioning Coach, Video Gait Analyst & Sports Massage Therapist with over 20 years experience working within the Health & Fitness Industry. Follow Matt on Twitter

References
1. Dunne.J.: Glute Dysfunction In Runners: Weakness Or Inhibition? (2012)
http://www.kinetic-revolution.com/glute-inhibition-or-glute-weakness/
2. Fredericson M. et al.: Hip Abductor Weakness in Distance Runners with Ilotibial Band Syndrome. (2000); Clin J Sport Med Jul;10(3):169-75
http://physio-optima.ca/bibliotheque/bit.pdf
3. Ireland M. et al.: Hip Strength in Females with and without Patellofemoral Pain. (2003); J Orthop Sports Phys Ther. 2003 Nov;33(11):671-6..
http://www.ncbi.nlm.nih.gov/pubmed/14669962
4.Robinson R. et al.: Analysis of Hip Strength in Females Seeking Physical Therapy Treatment for Unilateral Patellofemoral Pain Syndrome (2007) 10.2519/jospt.2007.2439
http://commons.pacificu.edu/cgi/viewcontent.cgi?article=1001&context=ptfac
5. Cichanowski HR. et al.: Hip Strength in Collegiate Female Athletes with Patellofemoral Pain. (2007); Med Sci Sports Exerc. 2007 Aug;39(8):1227-32.
http://www.ncbi.nlm.nih.gov/pubmed/17762354
6. Snyder J.: Evidence-Based Strength Training: Gluteus Medius. (2010 )
http://orthopedicmanualpt.com/2012/12/10/evidence-based-strength-training-gluteus-medius/
7. Bolgla et al.: Electromyographic Analysis of Hip Rehabilitation Exercises in a Group of Healthy Subjects (2004) DOI: 10.2519/jospt.2005.2066
http://www.jospt.org/issues/articleID.704,type.2/article_detail.asp
8. DiStefano LJ. Et al., Gluteal muscle activation during common therapeutic exercises. (2009); J Orthop Sports Phys Ther. 2009 Jul;39(7):532-40. doi: 10.2519/jospt.2009.2796.
http://www.ncbi.nlm.nih.gov/pubmed/19574661
9. Boren et al.: Electromyographic Analysis of Gluteus Medius and Gluteus Maximus During Rehabilitation Exercises. (2011)  Int J Sports Phys Ther. 2011 September; 6(3): 206–223.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3201064/

In large cities and other areas with power plants, industrial centers, or just lots of cars,  increased levels of pollutants in the air can become a real health hazard. When the air pollution gets bad, you’ll still probably want to get your run in. The question then becomes whether to put up with the drudgery of the treadmill or go outside and run in the polluted air.

This article will take a look at the effects of air pollution on athletic performance, with an eye both for training and racing in poor air quality.

Air pollution and running – the studies

The first major studies on air pollution and endurance were undertaken in the ’60s, ’70s, and ’80s, after it was decided that the 1984 Olympics would be held in smoggy Los Angeles.  Another big round of research followed in the early 2000s leading up to the Beijing Olympics.

Fortunately, these studies looked at all of the questions we’d be interested in: Does air pollution affect performance? Does it affect health? And are there any ways to mitigate its effects?

What studies say

In a fairly detailed review article published in the months before the 1984 Games, Roy Shephard at Toronto Western Hospital described the effects on the body of polluted air.  These were broken down by whether the chemical pollutants were oxidants or reductants.

Oxidants

• Oxidating smog, according to Shephard, includes carbon monoxide, unburned hydrocarbons, ozone, and oxides of nitrogen.

• While oxidating smog comes mostly from car exhaust, reductive (in the chemical sense) smog is the result of coal power plants and other industrial burners discharging sulfur oxides into the atmosphere.

• Among the pollutants in oxidant smog, carbon monoxide has a predictable, detrimental effect on your blood’s ability to transport oxygen using your red blood cells.  The carbon monoxide diffuses into your blood through your lungs, occupying the oxygen bonding sites on red blood cells, and is very slow to be removed from your body.  As the amount of carbon monoxide in your blood increases, your performance drops linearly, since there is steadily less blood available to carry oxygen.

• In areas with heavy smog, like Los Angeles or Beijing, up to five percent of all of your red blood cells can be overwhelmed by carbon monoxide, and at these levels, even muscular coordination and perception of time can be impeded.

• The other oxidant chemicals, like ozone and hydrocarbons, irritate your throat, nose, and airways.  When you exercise in polluted air, ozone in particular causes chest tightness and coughing.  Shephard cites a study which demonstrated an 11% decrease in oxygen intake after two hours of exposure to levels of ozone similar to those in polluted areas.

Reductants

• The chemicals in reductant smog have a tendency to irritate your lungs, because the sulfur oxides combine with water in the air or in your lungs to create acidity, which causes airway restriction along with the particulate matter also present in polluted air.  This problem is especially severe in athletes who already have asthma.

• Shephard also notes that the damage to the lungs and airways that results from air pollution exposure can also increase your risk for upper respiratory infections like the common cold.  The reasons behind this—damage to the delicate tissue at the surface of the lungs and airways—appears to be the same reason deaths from chronic respiratory diseases increase when pollution is bad.

How does this impact your performance?

Other studies have also linked sulfur oxides, ozone, and carbon monoxide to decreased athletic performance.  Exposure to pollutants generally leads to a predictable, linear drop in your ability to take in oxygen.

A study by Wayne Walborg and colleagues, for example, found that higher levels of oxidants in the air were correlated with slower cross country race times among high school boys in the Los Angeles area.

More work has also revealed that exercise exacerbates their effects, since the deep, heavy breathing you use while running both increases the total volume of air moving in and out of your lungs and also allows pollutants to bypass your nose, where the mucous tissues can trap some of the chemicals before they get to your lungs.

Final thoughts and recommendations

Unfortunately, when it comes to mitigating the effects of air pollution, there is not a whole lot that can be done.  Shephard recommends the following:

• Taking vitamin E and vitamin C supplements to mitigate the oxidizing effect of some of the chemicals in smog, but admits there is scant evidence for their usefulness.

• Aside from that, the best you can do is avoid the times of day with the worst air quality—rush hour in the morning and evening, for most American cities—and limit your time outside on days with particularly bad smog.

• Especially if you have asthma, it might make sense to move a longer or faster workout to a day without as much air pollution, or do it inside on a treadmill.

• You can check the air quality index and the forecast at airnow.gov, which comes with some useful maps and guidelines for air pollution levels.

• If you do decide to go ahead with a workout or race when air quality is poor, be aware that your oxygen intake will be impaired, so your times will likely be slower than on a day or in a city with clean air.

References

A very good question! But first things first…

Why do we need running shoes at all?

Relax, I’m not going to start preaching about barefoot running (although I’m not going to dismiss it either). But in order to discuss how we decide which trainers are suitable for us, it is useful to re-evaluate exactly what we are buying them for.

With that in mind, over the last couple of days I have been asking the runners I meet what they are looking for when they buy trainers. Collectively, the majority of them produced the following three reasons: protection, support, cushioning.

Protection

If by protection we are referring to avoiding glass & syringes, then wearing something on our feet obviously makes sense. This may well be the main contributing factor as to why, at least in my experience, it is rare to see runners training or racing in no shoes on at all.

Many of us could probably find less hazardous routes on which to entertain the theoretical benefits of barefoot running, but until clearer evidence supports such theories, most of us will probably pass.  However, if we’re talking about protection from running on hard surfaces then we are essentially looking at cushioning (more on that shortly).

Support

By support, most people are referring to stopping the medial arch of the foot “collapsing,” which brings us back to the whole supination/neutral/pronation paradigm used by most running shops to prescribe you a “suitable” trainer after watching you walk or run for a couple of minutes (or in some cases just standing you on a pressure pad, which in itself has no connection to how your foot acts whilst running). I am sure you are already familiar with the process:

• If the arch of your supporting foot drops “too much” you are labelled an “overpronator” and assigned a motion-control shoe that will in theory reduce the “overpronation”.
• If your arch does not drop “enough”, you are said to be an underpronator (or supinator), and assigned a flexible, cushioned shoe to absorb some of the shock that underpronator is said to cause.
• If you are somewhere in the middle, you are said to have normal pronation and are recommended a “neutral” shoe that in theory provides just the right amount of stability and cushioning.

As we saw last week, this model is heavily flawed and unsupported to date by any evidence. It is important not to let fear of injury or promises of recovery persuade you to be herded into one of the three pens (motion control, stability or neutral) however persuasive the sheepdog/sales person may be!

Cushioning

If you regularly run on hard surfaces like pavements, tracks and treadmills, you would think cushioning makes sense. Running shops can be very quick to stress this point if they “see” you as a heel striker. And yet, studies show (Scott, 1990) that peak loads at typical sites of injury for runners (Achilles, knees, etc.) actually occur during midstance (when your bodyweight passes over the supporting leg) and toe off (when your back leg pushes away from the ground).

These studies suggest that impact force at heel contact has no effect on the peak force seen at typical injury sites.

There is also growing evidence that when faced with higher impact forces from a harder running surface, your body makes natural adjustments to deal with the change in impact force – changes in joint stiffness, changes in the way the foot strikes the ground, and also via a concept called “muscle tuning” (pre-activation of muscles prior to impact).

Based on information received visually and from the previous foot strike, the body adjusts how strongly the muscles in your leg contract before the foot hits the ground again. Imagine jumping on a trampoline – your legs naturally stiffen in preparation for the soft landing.

Now imagine yourself jumping onto concrete – your legs naturally become less stiff in preparation for the hard landing. This natural adjustment is the result of sensory feedback from not only the eyes but also from the feet. In other words, the theory is that sensory feedback from the feet following one foot strike helps prepares the body for the next foot strike. If this is indeed the case, could excessive cushioning at the bottom of a trainer inhibit this natural sensory feedback?

Cushioning & injury prevention

The role that impact actually plays in running injuries is not at all clear. Studies by two highly respected biomechanics researchers, Dr. Irene Davis (Director of the Running Injury Lab, University of Delaware) and Dr. Benno Nigg (Co-Director of the Human Performance Laboratory, University of Calgary) have produced contrasting results.

Whilst Dr. Davis’ research links high impact loading rates with plantar fasciitis and tibia stress fractures, Dr. Nigg has found that overall injury rates are slightly lower among runners with high impact loading rates.

One possible interpretation of the above is that leg stiffness, as we considered earlier, is an important factor with certain injuries. Dr. Davis’ research linked runners who had suffered tibia stress fractures with higher impact forces and higher leg stiffness.

If tibia stress fractures are a consequence of high leg stiffness (for which I hasten to add there is as yet no evidence) then maybe runners susceptible to them should try wearing a less cushioned shoe and run on harder surfaces.

Just as we saw in our “landing on concrete” example earlier, in preparation for the harder surface, the body will reduce leg stiffness, which if the theory is correct could reduce susceptibility to tibia stress fractures.

At this stage it is all theory, and I draw particular attention to the words “maybe” and “try”. Always introduce changes slowly and gradually! Give your body a chance to tell you how it feels about the change before you do any harm to yourself!

So what trainers should I buy?

For those of you still clinging onto the hope that I or indeed anyone is going to be able to give you a structured model for trainer selection, I should probably put you out of your misery. There is no model. But do not despair. See it as liberation as opposed to a hindrance.

Yes, some people are recommended trainers and their injury disappears, but plenty are given the same advice and the injury continues. The journey to injury free running is best started with acceptance & application of the following mantra, as used by running coach James Dunne of Kinetic Revolution: Form Before Footwear.

As far as trainer selection goes, Pete Larson, anatomy professor, writer & runner with self diagnosed shoe obsession sums it up nicely: “I can run in just about anything as long as I’m careful to take things slowly and listen to my body.”

This is what I mean by “liberation.”

Part of Pete’s Running Shoe Collection, 2010. (Photo Courtesy of P. Larson)

In my opinion, one of the best things to so far emerge from the barefoot debate is the much larger variety of designs of shoe you can now choose from.

Having seen that heavy cushioning is not necessarily helpful to everybody, you should now hopefully be more confident to test, for example, some lighter trainers. Again, the secret is experimenting to see what feels comfortable for you. Bear in mind that a trainer that suits you for one distance, terrain or speed may not work as well for another.

You could also try trainers with a slightly lower Heel-Toe Drop than you are used to (the difference in height between the heel and the forefoot).

Traditional running shoes have a heel-toe drop of about 12mm. Vibram Fivefingers have pretty much a drop of 0mm. Going straight from 12mm to 0mm is not taking things slowly or listening to your body! There are plenty of 6-10mm transitional trainers on the market which will allow you to experiment more gently.

Though there is as yet no direct evidence for benefits of a lower drop, I personally see much logic in the argument that exposing your feet and legs to varying forces (in a controlled, sensible manner) could potentially make you a stronger runner and reduce injury.

Remember to listen to your body

If you run too far, too often, or too fast in a new pair of trainers, your body will let you know. Many of the running injuries we see in clinic are linked to a runner buying a new pair of trainers and thinking they can pick up their training program from where they left off. It’s more than that. Most runners actually run faster or further the first time they put on their new trainers (we all love new toys!).

• It is vital to respect the fact that your body will often need time to adjust to a new style of trainer. Put on a minimalistic shoe for the first time and run too far and your calves will soon let you know about it! It’s all about taking it slowly and listening to your body.

• If you experience a slight discomfort, treat it as a thoughtful message from your body that you need to break the new trainers in a little more gently. Put them away for a while. Go back to your favourite trainers then re-test the new ones with reduced time or intensity.

• Obviously, if the pain is persistent and affects your running whilst wearing other footwear then get it checked out by a professional, but in my experience most running injuries are the result of either ignoring a warning sign (not listening to the body) or too quick an escalation in frequency, intensity or time.

It may be the shoes, but it’s more likely to be you pushing yourself too much, too soon. Which brings me to my next point…

Use more than one pair of trainers

In order to break in new trainers, you will need to have your all time favorites at hand to wear in between. Your body will warn you if you are doing too much in your new trainers. Listen to it. Put them away for a week, continue with your regular trainers, then go back to the new ones.

Many runners I work with report that exposing their legs & feet to different forces via rotating the trainers they run in leads to (or at least coincides with) less injury. Given that the majority of running injuries are the result of repetitive strain, mixing it up kind of makes sense (and that goes for running surfaces as well). Invest in a few pairs of different style trainers – the chances are you will get your money back by less need for injury treatment!

Have you experienced success by changing to a new style of trainer? Maybe you already rotate different style trainers as part of your running program? We are always keen to hear from you and look forward to reading your comments.

Happy running!

Matt Phillips is a Run Conditioning Coach, Video Gait Analyst & Sports Massage Therapist with over 20 years experience working within the Health & Fitness Industry. Follow Matt on Twitter

References

Surprisingly, good runners come from both groups!

In past articles, we’ve looked at how important core strength is to having good running form and avoiding injuries, particularly to the knee.

Strong evidence exists that connects poor strength and coordination in the hip stabilizer muscles to IT band syndrome and patellofemoral pain syndrome or “runner’s knee,” two injuries that are quite common both in recreational runners and the high schoolers that I coach.

Two tests for hip strength and stability

Since the effect of hip strength on your running mechanics is a combination of strength and muscle activation, it can sometimes be tricky to assess both.  You can be strong, but not quite coordinating your hip muscles right, or you can simply lack hip strength entirely—both can increase your risk of injury.

Fortunately, with the help of some scientific research, I’ve been able to identify two tests for hip stability and strength that are quite good at identifying the kinds of deficits that can lead to knee injuries. 

In my own informal testing with my high school athletes, these tests have been pretty good at indicating who’s at risk for knee injuries and what the source of the problem is in runners who’ve already got ITBS or runner’s knee.

Test 1: The Glute Bridge

The first is a test for hip strength.  By doing a “glute bridge” exercise, then slowly lifting up one leg, putting it down, and then lifting up the other, you can check how stable your pelvis is when it must be supported by your hip abductor and external rotator muscles.

In strong, healthy runners (particularly those who do hip strength exercises often), the pelvis will barely move when you lift up one leg.  But in runners with hip strength deficits, there will be a marked “dip,” with the pelvis tilting down on the unsupported side.  This is easy to spot by yourself, but can also be confirmed by an observer.

What’s the evidence for this exercise?

A 2013 study by David Selkowitz, George Benneck, and Christopher Powers identified the single-leg glute bridge as one of the best exercises for hip stability, meaning it directly stresses your hip abductors and external rotators while minimizing the activation of other muscles which can help you “cheat” while stabilizing the hip.

And the static (or “isometric” in sports-science circles) nature of the exercise mimics the static portion of the running stride where your hip is supported by one leg.

As we’ve seen in previous articles, your hip will also dip to one side when you are running if you’ve got weak hip muscles—a phenomenon informally called “hip drop”—but it’s harder to see by yourself.

Test 2: Single Leg Squats

The second test evaluates the coordination of your hip stabilizer muscles during a dynamic activity.  For this test, simply do five or 10 single-leg squats, being sure to keep your torso upright and your knee about even with your toes.

While you are doing these squats, glance down at your knee.  Is it pointing straight ahead, or is it buckled or rotated inward? If your hip stabilizers are weak, or if they simple aren’t very well coordinated, you’ll find these single leg squats quite difficult to do without allowing your knee to wobble around or buckle inward.

What’s the evidence for this exercise?

Biomechanical research has connected the same mechanical motions observed in poorly-done single-leg squats (an unstable, wobbly, or inward-buckled knee) with knee injuries.

• A 2011 study by Reed Ferber and colleagues at the University of Calgary found that runners with patellofemoral pain syndrome displayed significantly reduced variability in knee mechanics—basically, less “wobble” at the knee—after completing a hip strengthening program, and a 2010 study also headed by Ferber, this time with colleagues at a number of universities, connected excessive knee internal rotation and hip adduction in women (an “inward-buckling” knee) with IT band syndrome.

• Another 2011 study by Crossley et al. directly tested the single-leg squat as a measurement of hip muscle function.The researchers had 34 healthy patients perform single leg squats, with three different clinicians rating each subject’s squats as “good,” “fair,” or “poor.”  The classifications between each evaluator were quite reliable, and more so, these findings correlated very well with direct measurements of hip muscle activation and strength using electromyography and dynamometers: those who had good hip strength and activation tended to be able to perform single-leg squats quite well, and those with deficits struggled with the single-leg squats.

Final message

You might find that you can manage the glute bridge pretty well, but struggle with single-leg squats.  This likely means that you’ve got sufficient static hip strength, but not enough coordination to sustain hip stability during the dynamic parts of the running stride, as your foot hits the ground and your knee bends to absorb the impact.  Or, you may struggle with both.

I haven’t seen anyone yet who’s been able to do single-leg squats, but struggles with the glute bridge, though it’s certainly possible.

But the best part about these two tests for hip strength is that they also function as good exercises to improve it! Whether you struggle on one, both, or neither of these tests, they are both good exercises to improve hip strength and coordination, hopefully preventing or at least reducing your risk for knee injuries.

If you decide you want to be more aggressive in your approach to hip weakness or instability and injury-prevention, we’ve put together an extensive program of running-specific hip, core, and general strength routines. The Bia, Atlas, Apollo and Ares routines not only improve hip and core strength, but will help you improve stability and range of motion. You can pick them up here.

References

In this article, we’ll shift from the metabolic process and focus on the physical activity portion of metabolism and discuss the ways in which exercise can affect energy balance.

Physical activity is the most variable component of one’s overall metabolism due to the fact that some individuals are very active while some are not active at all.

It is well known that physical activity is important for weight loss because it adds to the “energy expenditure” side of energy balance to help create a negative energy balance and thus leads to weight loss. But how much does it really effect energy balance and in what ways?

There are a number of proposed ways that physical activity, or exercise, is thought to induce negative energy balance. One or more of the following mechanisms is usually in play:

•  The direct energy cost of the exercise
• The effect of exercise on RMR
• The effect of exercise on the thermic effect of food and
• The effect of exercise on food intake

Energy cost of physical activity

Physical activity can be categorized two ways. One is the physical activity associated with our daily activities, such as what we do for work. The energy costs associated with construction work are much higher than those associated with a desk job.

When estimating one’s daily energy needs, we will typically multiply RMR by an activity factor determined by how active one is in their daily routine. This can be anywhere from 1.2 to 2.5 in the general population and can vary from day to day, week to week, month to month, or year to year.

The other consideration to make regarding physical activity is the direct energy cost of a single exercise bout. This energy or calorie cost of running  is actually smaller than what most runners might think.

While it is true that a two-hour long run “burns” a lot of calories, the energy expenditure associated with a single bout of energy is not quantitatively important unless it is repeated on a chronic basis (i.e. daily).

For example, a two-hour long run may burn 1200 calories, which seems like a lot for that day, but only equates to about 1/3 of a pound of weight loss. If that were the only exercise bout completed in a week, it would have a very minimal contribution to the overall energy balance equation.

With that said, daily exercise helps create a growing “bank” of burned calories which can become a significant contributor to weight loss, especially when combined with a modest reduction in energy intake.

Energy cost and body weight

Of course it should be noted that the energy expenditure associated with exercise is not the same for each individual, or even within the same individual.

The energy cost for a given activity depends on body weight and the level of training and skill and individual has with that activity.

Last week we learned that as body weight decreases, RMR will also decrease slightly. The same is true for the energy costs of physical activity, however this can also be affected by training adaptations.

Most endurance athletes are familiar with VO2max. It is a measure of the maximum oxygen intake that can be consumed by the body during exercise per unit of time. Oxygen consumption is linearly related to energy expenditure in that the more oxygen consumed during exercise, the greater the energy expenditure for that exercise bout.

The amount of oxygen required for an exercise bout is reflected by the intensity of the exercise.

• Low intensity exercise, such as slow jogging, is usually done at about 30-50% VO2max.
• Moderate intensity exercise, such as fast jogging or easy run pace, is usually done at about 50-65% VO2 max.
• High intensity exercise, such as a threshold run, is usually done at about 70-80% VO2max
• Very intense exercise can reach 100% VO2max

As we train, we gain fitness and increase our VO2max. This means we become more efficient at using oxygen so it requires a higher intensity to achieve the same percent VO2max, and thus same caloric burn, as before.

This is a good thing from the perspective of become a faster runner, but not so good when trying to lose weight.

Adaptations to training are often one reason why weight loss efforts seem to plateau despite maintaining, or even increasing, exercise.

Effect of exercise on RMR

Acute bouts of exercise have been shown to have acute effects on RMR. This increase in energy expenditure seen after an exercise bout is completed in due to excess post-exercise oxygen consumption. This phenomenon is sometimes referred to as the “post-exercise burn”.

• The increase in RMR is proportional to the intensity of the exercise and is usually only seen after about 80-90 minutes of high intensity exercise (70-75% VO2max). Duration of the increase in RMR is also dependent on the duration and intensity of the exercise bout and has been shown to be between 4-24 hours, with a maximum of about 36 hours post-exercise being observed.

• The degree to which RMR increases is variable and has been noted in the literature to be anywhere from 2-15%, with a 3-5% increase most commonly observed. To put this into perspective, if your RMR is 2000 calories, that could increase acutely by 60-100 calories. So although high intensity exercise does acutely affect RMR, it ultimately has very little impact on weight management.

Effect of exercise on energy intake

It is a widely held belief that one reason why exercise for weight loss doesn’t work is because we increase our energy intake to compensate, and often overcompensate, for any exercise-induced energy deficit (“burned calories”).

When exercise bouts are low in duration and intensity, we may tend to overcompensate with energy intake while when exercise bouts are long and intense, increases in energy intake may not be enough to fully compensate for the increase in expenditure.

While this may be true for some, energy expenditure and energy intake are not always coupled in this way. There are a number of other possible relationships that describe how one may change energy intake in response to exercise-induced energy expenditure.

The connection between energy and appetite

Another possible relationship is that exercise reduces appetite and suppresses energy intake.

Many times runners report not being hungry after exercise, especially after very intense workouts or long runs. This can make adequate recovery difficult, but could ultimately be a good thing for weight loss. However, from personal experience I know that energy intake isn’t actually suppressed, just delayed. It is likely that we compensate for energy expenditure in the following hours or days, i.e. we eat for yesterday and not for today.

Most evidence suggests that there is ultimately no change in hunger or energy intake in response to exercise-induced energy expenditure. A review by Blundell analyzed 48 intervention studies of various durations measuring energy intake in response to deliberate exercise. He found that 31/48 studies showed no change in energy intake while 9/48 showed increases in intake and 8/48 showed decreases in intake.

A final relationship may be that increases in exercise-induced energy expenditure alter food choices or nutrient selections. Indeed, we often make healthier food choices in conjunction with adopting a healthier lifestyle, such as choosing to exercise. On the other hand, we may also make poorer food choices as a “reward” for working hard and burning calories. This relationship is not as well studied but is worth paying attention to the next time you are deciding what to eat following a run.

Bottom line

The best formula for weight loss is daily exercise coupled with a decreased energy intake in order to create a negative energy balance. However, understanding how this formula affects metabolism is important for achieving and maintaining healthy weight loss. Here are a few tips to keep in mind, help you stay on track, and keep you from feeling frustrated when weight loss seems to stall.

• As you lose body weight you will hopefully be losing body fat, but you will also temporarily lose some muscle mass (fat-free mass). A reduction in fat-free mass correlates with a reduction in RMR, meaning that you will need to reduce caloric intake slightly more than before to compensate.

• As you train more and become a more fit and efficient runner, your VO2max will increase. This means that you will burn less calories than you previously did running the same workout unless you also increase the intensity and work harder (consume more oxygen/ work at a higher %VO2max) or increase the duration of the workout.

• A lower caloric intake than you previously had will also translate into a lower RMR. Although the differences may be small, if you are habitually consuming more calories than you need you may start to see that weight creep back up over time.

Running has certainly seen some evolution of thought over the last few years, much of it following the publication in May 2009 of Christopher McDougal’s best seller Born To Run, bringing with it bold claims that running barefoot (or wearing something as close as possible to barefoot while protecting you from environmental elements) can strengthen your feet, reduce running injuries, encourage proper running form, and improve performance.

Until then, the only experience many of us had of barefoot running was seeing the South African teenager Zola Budd on our television sets, running barefoot in the women’s 3000 meter race at the 1984 Los Angeles Olympics.

Barefoot running

Whilst some runners have praised a transition to barefoot running (along with the typical shift to forefoot striking that barefoot running encourages) as a cure for an injury they were suffering, others have not been so fortunate and have seen it bring the onset of new injury, despite religiously following a slow, progressive transition period.

Clinical tests to date have also produced conflicting results. Barefoot running has been seen to reduce the risk of certain running related injuries, but increase the risk of others. It’s as if what works for some does not necessarily work for others. Sound familiar?

Regardless of personal experience, production of conclusive evidence for the benefits of barefoot running is still an ongoing project.

Minimalistic footwear

The increased profile and interest in barefoot running brought with it demand for less restrictive, less cushioned footwear, with the idea of allowing the foot to move and work in a more natural fashion whilst still providing a certain amount of protection.

As a result, today there is a wide spectrum of minimalistic footwear that, though not as extreme as barefoot style shoes like the Vibram FiveFingers, typically aim to provide less drop (difference between heel height and toe height), less cushioning, a wider toe box (more room for the toes) and more flexibility.

Like barefoot running, conclusive evidence for the benefits of minimalistic footwear is still a work in practice. A 2012 review in the Journal of Strength & Conditioning titled: “Running Barefoot or in Minimalist Shoes: Evidence or Conjecture?” concluded:

“Running barefoot or in minimalist footwear has become a popular trend. Whether this trend is supported by the evidence or conjecture has yet to be determined.”

Traditional footwear

Before any of you take “lack of conclusive evidence” as a reason to dismiss the possible benefits of barefoot running or minimalist shoes, I should point out – and this may come as a shock to you – that there is no evidence either that traditional running shoes can reduce injury or improve running performance.

Yes, you read that right. Though you were maybe told in the sports shop that your cushioned, stability or motion control trainer will help prevent injury, there is no evidence to support it. The problem is, the model that has been used for the last sixty years and more often than not is still used to help you select which trainers suit you is based on, well… not a lot.

Foot types

If you have ever been to a sports shop to buy a pair of running shoes (or have received an “ankle-down” gait analysis), chances are you are familiar with the diagram below, or something very similar. It links three “foot types” (based on the height of the medial arch) with three corresponding types of recommended running shoe:

The origin of the idea to group feet according to the height of the medial arch is not clear. Ian Griffiths, Director of Sports Podiatry Info Ltd suggests it may stem from a method of assessing footprints devised in 1947 by Colonel Harris and Major Beath as part of an Army foot survey. The first time an image associating medial arch height with shoe type actually appeared in print could have been the 1980 “The Running Shoe Book” by Peter R Cavanagh.

What we do know is that since 1980, running shoes all over the world have been recommended and sold using the Foot Type model. Selection typically follows an “assessment” (often involving the subject stepping onto a pressure pad or being filmed from the ankle down whilst running) of how much the medial arch drops (referred to in the diagram as “pronation”) or doesn’t drop (“supination”), along with the idea that somewhere in the middle (“neutral”) is normal, healthy and necessary for injury prevention (more on that later).

• If the arch of your supporting leg drops “too much”, you are labelled an “overpronator” and assigned a motion-control shoe that will in theory reduce the “overpronation”. If your arch does not drop “enough”, you are said to be an underpronator (or supinator), and assigned a flexible, cushioned shoe to absorb some of the shock that underpronator is said to cause.
• If you are somewhere in the middle, you are said to have normal pronation and are recommended a “neutral” shoe that in theory provides just the right amount of stability and cushioning. Leaving aside the question of who decides “how much” dropping is normal, it is important at this stage to remind ourselves that both pronation and supination are natural, integral parts of foot biomechanics.

Dr Shawn Allen, Diplomate of American Board of Chiropractic Orthopaedists explains:

“The foot is a biomechanical marvel. 26 bones and 31 joints, working together in concert to provide balance, stability, and locomotion. As we walk or run, the foot is supposed to go through a series of biomechanical changes, so that it can either adapt to the environment or become a rigid lever for propulsion. When these mechanisms fail, problems usually arise. When the heel hits the ground, the arch of the foot is supposed to partially collapse (pronation), so that the foot can adapt to the ground; in this position, it is flexible and “unlocked”. After the weight of the body passes over the foot, the arch is supposed to retract, and the foot becomes more rigid or “locked” (supination), so that you can use it to propel yourself forward. If the foot remains in pronation for too long, or does not supinate correctly, problems will develop over time.”

Problems with assigning shoes according to degree of pronation

So, the running shoe recommendation model is based on the idea that at midstance, just before the full weight of the body passes over the foot, the best position of the subtalar joint is “neutral”, i.e. the foot perpendicular to the horizontal ground.

The argument is that this “neutral” position signifies optimum functioning of the foot, optimum pronation and supination. One problem with this is the fact that the subtalar joint has variable anatomy. In other words, function will vary from person to person, so the ‘optimum’ position to be in will also vary. Ian Griffiths explains:

“Studies have shown that the structural anatomy of the human subtalar joint varies from person to person and it has also been shown that the location of the axis of the joint can and does vary from person to person; this will of course directly influence the magnitude of pronation and supination seen.  In light of this sort of evidence it seems odd that there would be an expectation that all individuals could or should function similarly or identically.”

Taking the above into consideration, it should come as no surprise that there is no data or evidence that suggests “neutral” STJ alignment is linked with injury and/or pain free running. One study examined 120 healthy individuals both non weight-bearing and weight-bearing. Not one subject conformed to the criteria of “neutral” alignment.

Is there any evidence that “over-pronation” increases injury?

Almost all studies to date on “over-pronation” have found no evidence that it increases the risk of injury. A 2010 study concluded that the prescription of shoes with elevated cushioned heels and pronation control systems tailored to an individual’s foot type was not evidence based.

Another piece of research suggested the running shoe model was overly simplistic and potentially injurious. In fact, in this research, every ‘overpronated’ runner put into a motion control shoe during a 13 week half marathon training programme reported an injury.

Craig Payne, DipPod MPH, University lecturer and famed Running Research Junkie points out that lack of evidence for linking overpronation to injury may well be down to the methods used to measure pronation:

“The weakness of many of those studies is how they measured “pronation”; for example, some measure calcaneal eversion; some measure navicular drop; some do a footprint analysis; and some use a dynamic 3D kinematic analysis. The problem with that is that someone may be ‘overpronated’ on the measurement of one parameter and not ‘overpronated’ on another parameter.”

A study published this month by Teyhen DS. titled “Impact of Foot Type on Cost of Lower Extremity Injury” set out to determine the relationship between foot type and medical costs associated with lower extremity musculoskeletal injury, using a population of 668 healthy U.S. military healthcare beneficiaries in active military service for at least 18 months of the 31 month study.

It quantified level of pronation using the Foot Posture Index, a measurement of static foot posture that takes into account not one but multiple components that go into “overpronation”, devised by Dr Anthony Redmond, Arthritis Research Campaign Lecturer at the University of Leeds.

Whether static foot posture has much to do with foot posture whilst moving (e.g. running) is a discussion for another day. What the study did show is that of the 336 participants (out of the total 668) who sought medical care for lower extremity musculoskeletal injuries, a high percentage (no exact value available at this time) were those who had been listed as “extreme pronated feet” via the Foot Posture Index.

Future research will be needed to help see if degree of pronation via multiple component assessment (e.g. the Foot Posture Index) can be linked to injury. In the meantime, using just one component of “over-pronation” (e.g. medial arch height) to assign suitable footwear will continue to be a game of hit and miss.

Concluding considerations

• Is the whole running shoe recommendation model based on misconception?
• If it is, what model should be used, if any?
• There are certifications out there teaching shop staff how to sell running shoes. What are they based on?
• As a result of this debate, some are suggesting that runners should buy trainers based on “comfort” alone. Hard to imagine?

As I see it, just because an injury is present on someone with an “excessive” level of pronation (whatever that is…), it does necessarily mean that the level of pronation is the cause of the injury (correlation vs. causation).

It is imperative to consider and understand the biomechanics of the rest of the body (as well as foot posture) before reaching any conclusions. And even with all of that knowledge, it will still be a daunting task to be able to say “this is the running shoe you need!”

So, what should we base trainer recommendation on? A tricky question that we will consider next week. In the meantime, I am keen to know of your personal experience. What you are currently running in? What made you buy them? Have you managed to reduce injury via a change in footwear? Maybe a change in your footwear has led to an increase in injury? As always, I look forward to your comments!

Happy running!

Matt Phillips is a Run Conditioning Coach, Video Gait Analyst & Sports Massage Therapist with over 20 years experience working within the Health & Fitness Industry. Follow Matt on Twitter

References

While running on trails has a number of advantages, one drawback is that you are likely at a greater risk for sustaining an ankle sprain than if you stuck to the roads (though road runners are no stranger to sprains either, given the abundance of rocks, ruts, potholes, and curbs on the roads).

More problematically, once you’ve sustained one ankle sprain, you are at a higher risk for sustaining another.

Ankle sprain: never underestimate it

Though ankle sprains are often dismissed as a minor injury that takes care of itself, the scientific literature shows otherwise.

In one representative study by M.S. Yeung and colleagues at the Hong Kong Sports Institute, a survey of recreational and competitive athletes found that 73% had suffered from multiple ankle sprains, and more significantly, 59% of these reported recurrent problems like ankle pain, instability, crackling sounds in the joint, and weakness.

While this survey was of athletes among many sports, other studies suggest that there is no shortage of runners who get ankle sprains either.

The injury process

The initial injury process in an ankle sprain usually involves encountering an unexpected change in surface which “tips” the ankle to one side or another, injuring the ligaments. The commonality of recurrent problems, particularly ankle instability, seems to increase the risk for additional ankle sprains in the future, causing a feedback loop where smaller jarring impacts at the ankle become more likely to induce a sprain. This can lead to running on uneven surfaces or making diagonal, cutting motions very difficult, even when you have recovered.

Studies also indicate that suffering ankle sprains appears to affect your body’s ability to perceive ankle motion and maintain your balance.

A 1988 study by Stanley Garn and Roberta Newton is a good example—30 subjects from the US Naval Academy with a history of two or more sprains of one ankle were tested on their ability to maintain a single-leg balance stance and their ability to discern small movements at the ankle joint. The majority of the subjects were substantially worse at balancing and perceiving ankle motion on their “bad side” (the one which had suffered the recurrent ankle sprains) when compared to their other side.

Know the risks

Fortunately, there is some good scientific evidence that some simple balance training can reduce the risk of sustaining ankle sprains. Two similar studies published within the last 10 years demonstrate this.

First study

The first, conducted by Timothy McGuine and James Keene at the University of Wisconsin, tested a balance-training program on a group of several hundred high school soccer and basketball athletes during their sports seasons. Below is the outline:

• The balance exercises began with two weeks of single-leg balance variants (basic balancing, single-leg squats, movement of the raised leg) on flat ground, first with the eyes open, then in the next week, closed.

• In the third and subsequent weeks, these same types of exercises were repeated on a balance board (or “wobble board”), a platform with a domed bottom to increase instability.

• Each exercise was done for 30 seconds on each leg five times per week. Among the athletes in the control group (which did not do a balance program), 9.9% suffered an ankle sprain, compared to only 6.1% of the athletes who did do the balance program.

Additionally, as we would expect, the results showed that subjects who had suffered an ankle sprain in the past were twice as likely to suffer another one during the study. When the authors excluded subjects with a history of previous ankle sprains, the athletes who did the balance program were still less likely to suffer from an ankle sprain, though this finding just barely failed to reach statistical significance.

Based on this, it seems that balance training, while helpful for healthy athletes, is more beneficial for those who have suffered an ankle sprain in the past.

Second study

This finding was confirmed in the second study, published by Evert Vergahen and others in Amsterdam. Using a similar approach as McGuine and Keene, Vergahen et al. followed 116 volleyball players during their competitive season. Like in the previous paper, half the subjects followed a balance training program for several weeks, with the other half serving as a control group.

At the conclusion of the study, the subjects in the experimental group had suffered significantly fewer ankle sprains, but unlike in the McGuine and Keene study, this finding only held for athletes with a history of ankle sprains.

Conclusion

So, while there is some evidence that a healthy runner might benefit from doing single-leg balance training to reduce the risk of an ankle sprain, the most important finding in the papers we’ve reviewed is:

Runners who have already suffered ankle sprains in the past should definitely be doing balance training several times a week.

You can begin by following these few simple procedure:

• Balancing on one leg on flat ground

• Progressing later to doing squats and leg-swings first with your eyes open

• Performing the prior exercise with your eyes closed.

• Moving to an unstable  surface like a wobble board to increase the difficulty as you improve.

Doing these kinds of exercises will improve your balance and hopefully allow you to dodge the problems associated with recurrent ankle sprains, especially if you are a trail or cross-country runner.

References

The truth is, metabolism does have a lot to do with body weight and energy balance. Perhaps a better understanding of what metabolism is and how we can use it to work for us, instead of against us, is the secret to achieving and maintaining a fit, healthy body for running and for life.

Energy expenditure

It is widely known that if you want to lose weight, you have to create a negative energy balance. In other words, you must expend more energy than you take in.

Energy expenditure doesn’t just occur through physical activity. Our daily energy expenditure can actually be divided into three categories:

• Resting metabolic rate (RMR)

• The thermic effect of food (TEF)

• Energy expended for physical activity (i.e. training)

We will discuss the contribution of TEF and physical activity at a later date. Today, let’s just focus on RMR.

Metabolic rate

Resting metabolic rate is typically what we refer to as our metabolism. It is defined as the amount of energy (or calories) required each day to keep your body functioning while at rest.

More specifically, it is the energy that keeps the brain functioning, the heart beating, and the lungs breathing, in addition to many other cellular processes. It is responsible for about 60-75% of our daily energy expenditure, but may account for less in individuals who are very physically active.

Determining the RMR

RMR can vary greatly between individuals and there are a few personal characteristics that determine one’s metabolism. The first is body size. In general, larger people have higher metabolic rates than smaller people. It is based on surface area so that a greater surface area equates to a higher metabolic rate. Therefore if a tall person and a short person both weighed the same, the taller person would have a higher metabolic rate due to the larger surface area.

However, the composition of body weight is the biggest determinant of metabolic rate. Fat-free mass (muscle, bones, organs) is metabolically active (calorie-burning) tissue so the more you have, the higher your metabolism. If two individuals were the same height and weight, the one with more FFM would have the higher RMR.

In general, athletes have RMRs that are ~5% higher than their non-athletic counterparts due to more muscle mass as opposed to fat mass.

Knowing your FFM is the best way of determining your RMR and therefore your daily caloric needs. The preferred method of obtaining FFM is through underwater weighing. Other popular methods include air displacement and bone density scans. A full list with descriptions can be found here.

Once FFM is determined it can be used in a prediction equation, like the Cunningham equation, to determine RMR:

RMR = 370 + (21.6 x FFM[kg])

Other factors

Age and sex also have an effect on metabolic rate. One’s metabolism is the highest during periods of rapid growth such as infancy or puberty. This explains why it is so hard to keep the refrigerator full when you have a 16-year-old boy living at home!

As we age, however, we start to lose muscle mass and thus the metabolism begins to slow. It is estimated that we lose ~2-3% of our previous RMR for each decade of life past 30 years old.

Also, since women generally have more body fat and less muscle than men, men typically have higher metabolic rates but are still subject to declining RMR with age.

Other factors to consider when thinking about metabolism include:

• Hormonal disorders such as hyperthyroidism, which will increase your RMR, and hypothyroidism, which will decrease your RMR.

• Acute injury or illness can temporarily increase your energy expenditure.

• Having a fever increases the metabolic rate by ~7% for every degree increase above 98.6° F.

• Finally, living and exercising in tropical climates can increase RMR anywhere from 5-20%.

Weight loss

The big question is how to manage weight loss and metabolism to find a healthy weight that will allow you to perform optimally, but is also easy to maintain. Awhile back we posted an article about Healthy Weight Loss, which provided tips on how to lose weight without sacrificing performance. One of those tips was to make sure you don’t cut calories too drastically.

1. Having too few calories can lead to the body breaking down protein, and therefore muscle mass, for energy. As we just learned muscle mass is the biggest determinant of metabolic rate and the less of it we have, the lower our metabolism will be.

The lower the metabolism, the less calories are needed for daily maintenance, and the harder it becomes to lose weight.

2. Another issue is that the more we restrict our calories, the more efficient the body becomes at using the calories that we do give it.

Normally efficiency is a good thing, unless we are trying to lose weight. When trying to lose weight, or create a negative energy balance, we don’t want the body to be efficient at using calories so that it has to work harder and thus burn more calories.

3. The final difficulty involving weight loss and metabolism is that as we lose weight, we require less energy (because RMR is determined mainly by body mass). This means you need to continually decrease your intake to account for the decrease in metabolic rate.

Tips for managing weight loss and metabolism

• To off-set the natural decline in metabolism that comes with age, start and continue a weight training program and do it 2-3 days per week to preserve lean muscle mass.

• To avoid big drops in RMR, limit calorie restriction to ~15% less than what is required to meet your maintenance and training needs. So if you needed 2300 calories a day to meet your RMR + training expenditures, you should only reduce that by ~345 calories per day (consume ~ 1955 calories per day).

• Be realistic about your weight loss goals and once you reach those goals, stop dieting. Your RMR will return to normal once calorie restriction has ceased and a normal caloric intake is resumed.

• Don’t fight against your metabolism but learn how to structure your nutrition to fit with it. Some factors contributing to metabolism are out of our control or very difficult to change. Furthermore, metabolism is a finely tuned and highly regulated operation of our bodies and we function best when it is in balance.

It is important that we remind ourselves that this change can be for better or for worse, so when modifying our running form it is vital that changes are made gradually (5-10% increments in the case of cadence) and that we listen to the body throughout the process.

“Correct” running form is very much individualized; what works for one will not necessarily work for all.

Leaning forward: does gravity help?

One idea that has gained popularity through the emergence of structured running styles is that by leaning forwards when we run we encourage “gravity to help propulsion.”

Although I am of agreement that a slight forward lean can indeed help increase running efficiency, I sometimes feel that attributing it to “getting help from gravity” can mask what I regard as a more beneficial explanation of the purpose of a forward lean, and help runners avoid the common error of leaning forwards from the waist as opposed to leaning the whole body slightly forwards in a straight line, from ankle to shoulder.

When Amby Burfoot, Editor-at-Large for Runner’s World, asked running expert panelists Michael Tammaro, Ph.D. (Physicist), Steve Magness (assistant coach to Alberto Salazar at Nike’s Oregon Project), and biomechanist Irene Davis, Ph.D. (director of the new National Running Center at the Spaulding Rehabiltation Hospital in Boston) if leaning forwards helps you run more efficiently by letting gravity do some of the work, the consensus was:

“Gravity can do nothing to improve your running efficiency on a flat surface. That’s because gravity provides no horizontal force; it simply pulls you back down to the earth.”

All three of the panel did however favour a slight forward lean while running.

So what’s it all about?

The importance of hip extension

Last week we saw that during swing phase (when the foot is in the air, from toe-off to foot strike), propulsion of the leg forwards is a passive movement (i.e. with no conscious effort) using a stretch-reflex similar to a sling-shot (catapult in British English).

Photo Courtesy of Nan Rudnik

The drawing back of the slingshot is equivalent to the hip flexors (at the front of the hip) lengthening under tension. As the body moves over the weight-bearing foot, the hip flexors store elastic energy that will later be used for propulsion. In other words, the more we manage to lengthen the hip flexors under tension, the stronger the forward propulsion (firing) of the leg will be.

So, let’s imagine what happens if you bend forwards at the waist whilst running. You are in effect reducing the range of movement available in the hip flexors, reducing the amount of tension you can achieve, and thus reducing the level of propulsion. In other words, you are reducing the power of the sling-shot.

This is why having restricted range of movement in the hip flexors can limit running efficiency. The level of propulsion is limited by the amount of elastic energy you are able to store in the hip flexors during hip extension (and likewise during knee and ankle extension where the stretch reflex is also used).

Use it or lose it

Unfortunately, making a living for most of us involves holding the pelvis in a relatively fixed position throughout the day, be it sitting in front of a computer, at the wheel of a car or standing in front of a whiteboard.

The static nature of our daily life is one reason why the hip flexors (at the front of the hip) lose the dynamic mobility required for optimum running efficiency. As a result, runners with restricted hip flexors typically tend to achieve hip extension (get the supporting leg behind them) by dropping the pelvis forward and arching the lower back. This allows the body to pass over the weight bearing foot without the hip flexor needing to lengthen so much.

However, as we have seen, less lengthening of the hip flexors under tension means less storing of elastic energy, meaning less propulsion. By reducing the efficiency of the running action, the lack of pelvic stability can create extra loads on the leg muscles and/or increase stress through the lumbar spine and pelvis. Either of these may increase the chances of injury.

Lean from the ankles, not the waist

Promoting efficient hip extension is one of the main rationales behind adopting a slight forward lean when running. The lean itself needs to start at the ankles and promote alignment of the whole body in a straight line, all the way up to the shoulders.

Maintaining this alignment over long distances however does require a certain level of conditioning, which is why strength and mobility exercises play such an important role in improving running performance.

Weak hamstrings, glutes and lower back can lead to too much of a forward lean, whilst tight quadriceps and hip flexors can encourage leaning forwards from the waist.

Typical cues include “lead with the hips”, “keep your hips pressed forward” and “tuck your backside under your hips” but unless you have sufficient strength and dynamic mobility to maintain such alignment, the coach can keep shouting as much as they want.

Running Biomechanics researcher Jay Dicharry describes how restricted hip extension can also cause runners to run in the “back seat” with their weight over the heel. According to Jay’s studies, this can promote overstriding and the associated problems that we considered in last week’s article.

Testing your hip flexor mobility

A good way to test your range of movement in the hip flexors (all be it in a static environment) is the kneeling tilt. Normally, this is how it goes:

1. When you first get into the kneeling position (see photo below), note how much tension you feel up the back leg, from the knee to up the thigh and across the hip. The chances are you will not feel too much (as your body will tend to hold your pelvis in a position that avoids tension).
2. Try and tilt the pelvis upwards, such that the waistline at the front of your trousers moves to level or a little higher than the line at the back (as in the right photo below).
3. In other words, tuck your backside under your hips. For many, this movement will not come easily as it requires a coordination of muscle recruitment that your body is probably not familiar with. You may need to practice the movement lying down (tilting your pelvis so your lower back touches the floor) in order to engage the necessary muscles, and then try it again in a kneeling position.
4. Those of you of who can tilt the pelvis upwards (without moving the rest of the body) should now get an indication of any restrictions you may have in hip flexion.

As is often the case, the test becomes the exercise to reduce restrictions. Don’t forget to test and compare both sides!

No one running style reigns supreme

Having given so much weight to the benefits of a slight forward lean from the ankles, it is once again important for us to remember that no one running style suits everybody or indeed wins all races, even at elite level.

The screenshot below taken from the Boston 2011 Marathon shows Gebre Gebremariam (in the green singlet) who finished third with a personal best of 2:04:53 (third also in 2013 with a time of 2:10:38), and Ryan Hall (blue/red singlet) who finished 4th with an American record time of 2:04:58 (but sadly had to pull from Boston 2013).

Just 5 seconds between them, and yet the differences in style are obvious: Hall showing a slight forward lean whilst Gebremariam exhibits a very upright torso.

Photo Courtesy of Pete Larson

“What about the 2011 winner and runner up?” I hear you say. Well, in the photo below, you can see Geoffrey Mutai (in the green singlet) who won with a time of 2:03:02, and Moses Mosop (black/red singlet) who came second in 2:03:06. Maybe a slight forward lean is the way to go for the majority of us!

Photo Courtesy of Pete Larson

Many thanks for reading. The feedback for this series of articles to date has been very encouraging. As always, feel free to use the comment box below for debate as the world of running performance is rarely black & white! We welcome your personal experiences, questions and suggestions for future articles.

Happy running!

Matt Phillips is a Run Conditioning Coach, Video Gait Analyst & Sports Massage Therapist with over 20 years experience working within the Health & Fitness Industry. Follow Matt on Twitter

References

While a vitamin by name, vitamin D is, in truth, a hormone with multiple chemical variants. Also, unlike other dietary vitamins, your body is capable of synthesizing vitamin D internally in your skin by using ultraviolet light (most often from the sun) and precursor chemicals related to cholesterol, present in your body in abundant quantities.

Vitamin D is also rare in foods, with the notable exceptions of mushrooms (which also synthesize their vitamin D using sunlight) and fish oil. Ultimately, most people get the majority of their vitamin D via synthesizing it in their body with sunlight.

Since many people across the country and the world live in areas that are sun-starved for much of the year, scientists have discovered that a large proportion of people have some form of vitamin D deficiency.

One recent study of teenagers in Massachusetts found that about one in four are deficient in vitamin D, and that low levels of the vitamin are more common in the winter and in those with darker skin (who need more sunlight to synthesize vitamin D).

Does vitamin D affect athletic performance?

• A 2008 review study by John Cannell and collaborators cites a study of Finnish gymnasts and runners, which found that an astounding 67% were deficient in vitamin D—though these results could have been skewed by the gymnasts, who train and practice mostly inside.

• Another study conducted in 2010 involving collegiate athletes at the University of Wyoming found that the number of athletes with healthy levels of vitamin D dropped from 76% in the fall to 15% in the winter.

• Additionally, the athletes with higher levels of vitamin D were less likely to get sick. In a review article authored by two of the scientists from the University of Wyoming study, Willis and Larson-Meyer argue that, given the emerging connection between low vitamin D levels and chronic inflammatory and autoimmune diseases in elderly people, we ought to be concerned about vitamin D levels in athletes.

• Low vitamin D levels could perhaps also lead to illness or injury in athletes by influencing immune and inflammatory reactions, according to Willis and Larson-Meyer. These concerns were expounded on by Willis and Larson-Meyer in a longer review article, which cited studies which found vitamin D deficiency in a large proportion of patients at an inner-city clinic who complained of vague muscular pains or fatigue.

• Another study they cite found that supplementation with vitamin D₃ resulted in improvements in back pain—though any study on back pain treatments ought to be approached with caution, as most cases resolve spontaneously.

Vitamin D supplementation for athletes

For athletes at northern latitudes, especially those with darker skin or who train and compete indoors, Willis and Larson-Meyer recommend exposure to the sun, if possible, for 5-30 minutes during the middle of the day, or taking a vitamin D supplement which provides 1000-2000 IU of vitamin D₃ per day.

Other studies have used somewhat higher dosages with no apparent ill effects. They emphasize caution with sun exposure, since it can increase your risk of skin cancer when done excessively.

Vitamin D and athletic performance

When it comes to actual performance, there are unfortunately no solid studies as of yet that have directly looked at whether athletes with low vitamin D levels perform worse than those with healthy levels, or whether vitamin D supplements can boost performance.

Cannell et al., however, cite a fascinating series of papers from the 1930s to 1950s, originally published in Germany, which found that sun-like ultraviolet light exposure over several weeks had a consistent, positive impact on the athletic performance of the studies’ subjects, in tasks ranging from the 100m dash to physical fitness tests in schoolchildren.

The most plausible explanation for this boost in performance, according to the authors, is increased synthesis of vitamin D by the body as a result of the ultraviolet light exposure.

Additionally, seasonal performance, as measured by muscular strength increases relative to a standardized training program, seems to peak along with blood levels of vitamin D, which vary throughout the year due to sun exposure. This peak appears to occur in late August and September, with vitamin D levels and muscular training response both dropping sharply by November.

Final thoughts on vitamin D

The complexities of vitamin D in the body are a relatively new discovery. Given this, it shouldn’t be too surprising that studies are lacking on its effect on athletic performance.

There is a swelling body of evidence that connects low vitamin D levels with both acute and chronic illnesses, as well as general malaise in sedentary people, but high-quality modern studies on athletes and their performance are critically lacking. Until they are published, the most we can say is that there is some circumstantial evidence that vitamin D can have an impact on performance by influencing your overall health and recovery.

If there is a deleterious effect to having low vitamin D levels, these people are mostly at risk:

• People with dark skin
• People who live further away from the equator
• People who spend little time outdoors

The guidelines for maintaining optimal vitamin D levels that are presented in the studies we looked over are:

• Large areas of skin exposure to full sunlight for 5-30 minutes several times per week (dependent on the season, your skin tone, etc.) and

• Supplemental vitamin D with dosages ranging from 1000 IU to 5000 IU per day.

As the science evolves, these guidelines will probably become more clearer as will the role of vitamin D in overall health and athletic performance.

References