Is treadmill running the same or easier than running outside

I go to my local community center to lift and stretch out almost every day. Even in the spring and summer, there are always at least a few people pounding away on the treadmill. I can’t help but wonder, “With such beautiful weather outside, why are they stuck inside on the treadmill going nowhere?”

It was partially that question that spurred me to look into this week’s topic: the scientific research on the differences in treadmill and “overground” (or in layman’s terms, “regular”) running.

At first glance, they seem the same. A physicist might even argue that there shouldn’t be any differences, since it’s just a matter of frames of references. But it turns out that, because ground is moving, instead of the runner on top of it, there are a few key differences in your biomechanics on the treadmill, your perception of your own running, and the physiological demands placed on your body.

Biomechanical differences between treadmill and overground running

The first study we’ll look at, published in 1995 by Nigg, De Boer, and Fischer at the University of Calgary,1 examined the biomechanical differences between treadmill and overground running.

Using two high-speed cameras to capture a front and rear view of a group of runners, first running on a treadmill and then running on a road, the researchers tracked the motion of their joints throughout their gait cycle. While a number of variables changed, the only one that was consistent across all subjects was foot angle at touchdown.

On a treadmill, the runners all landed with flatter feet (less ankle dorsiflexion) than when they were running on land.

Many other variables changed in a “subject specific” manner, but the changes were not consistent across all subjects. This probably indicates that we all adapt to treadmill running in our own way, and may find that it stresses our body in slightly different but unpredictable ways.

Another study done two years later by Wank, Frick, and Schmidtbleicher in Germany did a similar study of the biomechanics of treadmill running,2 but extended their research by using electromyography equipment, sensors that can identify when your body activates your leg muscles and how strongly.

Like Nigg, De Boer, and Fischer, this study found flatter foot placement at footstrike. But, perhaps explaining the cause, they also found that runners have a more pronounced forward body lean, shorter stride length, and a higher stride frequency. They also spent less time on the ground.

Wank et al. proposed that the treadmill gait was a response to a feeling of instability on the treadmill—the runners quickened their stride, plantarflexed their ankles more, and spent less time on the ground since their body sensed that the treadmill was an unstable surface.

Some researchers have also suggested that there is an inherent instability on many treadmills because the belt momentarily stops when the foot lands on it, pinching it between the shoe and the steel plate below the belt. The electromyography studies, however, found little difference between treadmill and overground running, leaving the instability hypothesis unproven.

The brain’s perception of running on a treadmill

A much more recent study, published by Kong et al. in February of this year, further examined the brain’s perception of running on a treadmill.

In a very clever design, a group of runners first ran at a self-selected pace on a track for a few minutes, then immediately hopped on a treadmill and were told to adjust the speed of the treadmill to the pace they were running on the track.The only catch was that the runners were not allowed to see the pace indicator on the treadmill!

After running for a few minutes on the treadmill, they again hopped onto the track and were told to run the same speed again.

Interestingly, though the runners managed to run the same pace on both occasions on the track, their perceived speed on the treadmill was drastically different.

While the runners averaged about 6:50 pace on the track, when they adjusted the treadmill to what felt like the same pace, it was actually two minutes per mile slower!

Now, I have some doubts about whether this effect applies to everyone. The researchers don’t say whether the runners were adapted to treadmill running or not—this could make a big difference in how they perceived their effort. But this confirms what a lot of runners already know: running on a treadmill can feel a lot harder than it is.

Physiological demands of treadmill running versus regular running

And, what’s worse, in terms of physiological demand, it turns out treadmill running is easier!

Because of the lack of wind resistance, your oxygen consumption for a given pace on a treadmill will be lower than it would be overground.

Fortunately, this can be counteracted by adding a small incline to the treadmill, as demonstrated in a 1996 study by Jones and Doust.4

These researchers compared oxygen consumption levels in a group of runners at a range of paces both overground and on a treadmill at a variety of inclines.

They found that a 1% incline offsets the lack of air resistance most accurately, leaving the physiological demands between overground running and 1% incline treadmill running similar. (click to tweet)

The only problem with this is that is exaggerates the changes in biomechanics we observed earlier! If the ground is at an incline, your foot placement automatically becomes flatter, and your body lean increases as well.

Summing it up

So, there really aren’t too many advantages to treadmill running, at least during the sunny months of summer.

Treadmill running has a double-whammy of feeling harder but being easier. The difference in physiological demand can be offset by setting the treadmill to a 1% incline, but there’s no guarantee the incline measurement on a health club treadmill is accurate!

If there’s one redeeming quality in treadmill running, it’s from the changes in biomechanics. If you’ve got an injury that’s bothering you, there’s a chance treadmill running might not be as stressful. I’ve had bouts of tendonitis of the extensor tendons, on the top of the foot, which control the ankle’s dorsiflexion. Since foot placement is flatter on a treadmill, these tendons don’t have to work as hard, which enabled me to get back into running a few days earlier.

But, these special cases aside, there’s really no reason not to “hit the road” and ditch the treadmill if the weather’s nice outside!

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References

1. Nigg, B.; De Boer, R. W.; Fisher, V., A kinematic comparison of overground and treadmill running. Medicine & Science in Sports & Exercise 1995, 27 (1), 98-105.
2. Wank, V.; Frick, U.; Schmidtbleicher, D., Kinematics and electromyography of lower limb muscles in overground and treadmill running. International Journal of Sports Medicine 1998, 19 (7), 455-461.
3. Kong, P. W.; Koh, T. M. C.; Tan, W. C. R.; Wang, Y. S., Unmatched perception of speed when running overground and on a treadmill. Gait & Posture 2012, 36 (1), 46-48.
4. Jones, A. M.; Doust, J. H., A 1% treadmill grade most accurately reflects the energetic cost of outdoor running. Journal of Sports Sciences 1996, 14 (4), 321-327.

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14 Responses on “Is treadmill running the same or easier than running outside

  1. Have to disagree with a few assertions.

    1. Treadmills may be physiologically different in oxygen uptake, but I would argue the outcome is negligible. Air movement indoors (more often than not) is less fluid (air is a fluid) than outdoors, body heat exchange isn’t as efficient, and both factors can make it more difficult in relation to running outdoors.

    2. Most treadmill running samples (that I’m aware of) are of short duration. I’ve always understood (from studies by Jack Daniels) that the longer one spends on the t-mill, the less overland variation there is.

    3. The primary difference between overland and t-mill is rate. With overland running, you can run a 6:40 minute mile and within that mile run any million different combinations of pace. On the treadmill, you set the mill at 9.0 mph and 1% and you run one mile in 6m40s with no variation in pace. The latter is much more difficult.

    Treadmills are a great tool, for a number of reasons, chief among them being tempo runs and longer marathon pace runs. I know of (and know) Olympians that use them year around, male and female. The blanket “they’re easier” is simply mis-understood in its application.

    • Thanks for the comment, Eric. Interesting points on one and two. I actually haven’t looked at those two variables myself, so I appreciate you pointing them out. Definitely an interesting take.

      However, I have a different opinion on your third point in that pacing on a treadmill is harder (well, harder in a specific way, because I do agree that not having the ability to succumb to natural pace fluctuation is more difficult). I actually find pacing on a treadmill to be a disadvantage in relation to race specificity or teaching yourself how to pace. I think it’s easier to just plug and forget and focus on running hard whereas when outdoors you really have to pay attention and develop a feel, otherwise you end up all over the place during a race. Just my take.

      I totally agree that some people make treadmills work for them, whether it be out of necessity or preference. Not my cup of tea, but whatever helps a runner get their mileage in is a great idea to me.

      Thanks again!

  2. In my training for half marathons and 10Ks over the past three years, I have mainly used a t.m. for preparation, with very few outdoor runs included. Last year when running the Columbia Gorge marathon in Oregon, I completed it 30 MINUTES before my estimated time, and this year’s Bolder Boulder 10K in Colorado I finished 3 MINUTES 20 SECS faster than my previous year! You don’t get a break from your pace on a t.m. (as long as you don’t touch the buttons:) even when you increase the incline. When running outdoors it’s very easy to slow down on those inclines because there is no belt making you keep the intended pace. I have found for my own training that keeping the “dreadmill” at a 1% to a 1.5% incline has dramatically, and consistently, improved my PRs. On at least one to two days a week I will up the incline to a 6% or more and run quarter mile splits, always keeping my pace consistent. I have found that when I decide to do a run outdoors, my time is a pleasant surprise when my miles have been completed because I always feel as though I am running slower than I actually am, and I am convinced that it’s been my consistent HARD work on the tread! When people comment that someone on a tread is running and going no where, I have to disagree! We are going for that new record time that we did not get the year before! A good training plan and guts is what it takes, whether indoors or out, we are ALL KENYANS:)

  3. This is a favorite topic of mine. I have done a lot of running on treadmill but stopped totally after I started training for marathons. My personal opinion is if the goal is to run long distances,1/2 or full marathons then running outside helps. We have the luxury of varying our pace at will.You will not to be forced to see the time/pace/distance statistics that can keep you bothered.
    Running on treadmill can be boring especially if you are running for more than 30 mins.

  4. Okay, let’s pretend it’s a gazzilion degrees and almost the same humidity. The gym is no picnic, but it’s cooler than outside. And the local high school has the track I usually run on locked up for stadium renovations. (probably hopping the fence and showing up in the local police blotter isn’t a great idea, although I’m tempted).

    What is the best way to adapt speed work, or speed improvement to a treadmill? I hate those things, but at some point the weather makes you say “uncle”, and in the mid Atlantic the next week that’s how it is going (assuming there is electricity to power the treadmill).

    • Hi Michael, can’t blame you for hitting the treadmill – brutal week of weather. I don’t think you need to do much to adapt workouts. Basic workouts like tempos and easier intervals can just be done as normal. For speed development, I would basically just add 10-20 seconds of running before the maximum speed portion of the interval. For example, if you have 100m as fast as you can, run 10 seconds to get yourself and the belt up to speed and then go for it. When done, slow down the speed for 10 seconds and then jump off. This should keep the belt moving at a good rate, get you up to max speed, and still be safe. Hope that helps.

  5. Treadmills are a great piece of exercise equipment, not only do you get to exercise your legs, your arms also get to work out as well.Treadmills also have speed settings, so you can choose the speed that is right for you. Beginners can start with a small jog.`

  6. I like treadmills. Outside, there are constant obstacles and my left ankle has always been prone to rolling / sprains since early childhood … and my right knee is a bit dodgy from cycling. I like the give in the belt for less chance of injury (though running along the rock-strewn ground of the Cornish coastal paths is fun if a bit risky for me).

    I find treadmills particularly more useful than running outside for …
    1.) If one is heavy (I put on a lot of weight due to stress … got up to 223 pounds by November 2012). Treadmills seem a lot less stressful on my body. nb: I’m down to 170 pounds now – 23rd July 2013. (172cm height).
    2.) Safety … from cars, insects, marauders, and many potential sources for accidents. And also … fewer pollutants – e.g. vehicular / pollen etc.
    3.) Weather independence (from chest infections in extended cold Springs, to dehydration and sun-burn in heat waves).
    4.) Improving pace.

    I’m still 14 to 20 pounds overweight, 40 years old in a few weeks, and have my 10Km time down to just under 40-mins on the treadmill. From experience, I know I can run faster on the road during race conditions than I can on the treadmill … because of the only downside (for me) of the treadmill … being that while the gym is set at 16 celsius, with no air flow I tend to overheat which is less of a problem in appropriate weather outside.

    I do like running outside … but find it too problematic for self-improvement and better health. Its good for occasional fun. Thank goodness for treadmills!!!

  7. Hey coach! Great article.
    I must say I’m kind of doing a little experiment of my own to see how using the treadmill for training affects my times on road, in the past my PB’s were set on the road, and when coming to a treadmill I assumed it would be easier, obviously this was wrong and I find it interesting that it feels harder. For the last 8 weeks I have been carrying out 2 5k runs a week on the mill and I have been able to produce times between 19:35 and up to 20:43. I was surprised at my first findings as my best present road 5k time was 20.06.

    The only flaw I can think of in this little test, is doing 5k mill repetitions just going to condition the body and the road time would be quicker anyway?. I think if my road time is slower, I could say as a result of not road running in two months must be a factor, and if the time is a improvement then it’s the reps or the mill has a higher perceived difficulty.

    I have also wondered about air quality/density in a small gym like mine with quite a few people in it. Surly the extra ratio CO2 in that space may have a impact? and is this why It seems more difficult?. Out in the open and even better in the Forrest on a cool day O2 will be more denser perhaps.

    I’ll post new time when I have a “overground” run,

    • Well, had the first over ground run in about 8-10 weeks only treadmill training, it’s a massive mistake to only use the mill, the road was so tough, I forgot how hard it is , when I say hard I mean the pounding action, the breath being knocked out of you and the wind resistance that accompanies it.

      I feel that the mill has softened me up somewhat,my calves ached in different places, I can run with rytham on the mill without thinking, on the road pacing yourself is a skill you train into yourself.

      I ran 3.51 miles @ 7:08 pace. I now think if you want to run fast on the road you need to train on the road, use tread mills for sure.but they aren’t by no means a replacement for the real thing.

      So in conclusion, the treadmill isn’t the same at all and is loads easier.

  8. Pingback: Treadmill Running: Harder or Easier Than Outside? | Health & Wellness Chicago

  9. I’ve been doing interval training for 30minutes @ 1-2 incline 5x a week on a T.M. I’ve improved ALOT from using just a T.M. My mile overground was 8min 57sec, But after training on a T.M for about 2 weeks its gone down to 7min 47sec

  10. I find it much harder to maintain a fast pace on the treadmill. I think it’s as the surface is softer and steals rebound from the ground, or that my speed reading is erroneous.

    Eg I can do under 6 mins for a mile, I do sub 21 for 5km
    But even 8 mi/ mile on treadmill feels real tough. I was doing 6:40 pace on treadmill today and after just 3/4 mile I thought I was going to die.
    I think it’s at least 1 min/mile harder

    I do find my legs don’t hurt so much after a long fun though.

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