Will Improving Your Overall Athleticism Reduce Your Risk of Stress Fractures?

Most runners know somebody whose training or racing ambitions have been sidelined because of an injury caused by another sport.  Whether it’s a torn ACL from playing a pick-up game of soccer or a sprained ankle from a rec basketball league, “other sports” have a reputation for causing trouble when runners try their hand at them.

Traditionally, many runners are uncoordinated and unskilled at ball sports, so they tend to avoid them. Moreover, not only do runners perform poorly, they also often get hurt while doing so.

But some fascinating studies published in the past few years are indicating that this might be the wrong way to look at ball sports and general athleticism in relation to running.  Instead of merely causing injuries and soreness, participating in ball sports might confer a protective effect against some injuries because of the adaptability of your body.  We’ll take a look at these studies to figure out exactly what’s going on.

Running, ball sport, and bone strength

The first among these studies was published in 2000 by a group of researchers led by Charles Milgrom in Israel who were evaluating risk factors for military recruits who would develop stress fractures.

In a series of studies, the researchers looked at the effects of pre-boot camp activity levels on stress fracture risk in Israeli military recruits.  The recruits were surveyed on their activity levels, then followed during their basic training.  Surprisingly (and in contrast to some other military studies), being a runner did not confer a significant protective effect against stress fractures during military service. However, recruits who had played ball sports (typically basketball for the recruits in this study) for at least two years before military service suffered significantly fewer stress fractures than those who did not.

In a follow-up study, the same research group measured the strain on the tibia bone during walking, running, and basketball, finding that the peak stress on the bone was up to 50% higher during a basketball game when compared to running.  The researchers surmised that regular exposure to these higher stresses in the years before the ball-sport athletes became military recruits caused them to develop stronger and more robust bones, and hence more resistance to stress fractures.

Another study examining runners, ball-sport players, and bone strength was published in 2007 by Michael Fredericson and others at Stanford University.  Using a sample of 15 elite male soccer players, 15 elite male runners, and 15 sedentary men, Fredericson et al. used an x-ray machine to measure the subjects’ bone density at several locations in their skeleton.

Though the runners hand stronger bones than the sedentary subjects at places which are directly loaded on impact, like the heel bone, they are outclassed by soccer players, who have stronger bones everywhere as measured by bone density: whole-body, hip, leg, spine, and heel bone.   This is probably because of the dynamic nature of playing a ball sport like soccer: unlike the simplicity in running, ball sport athletes make a huge range of different cutting and turning motions on a regular basis, putting a wide variety of stresses on their skeleton.  Compared to ball sports, runners, by contrast, put moderate but repetitive stresses on their bones, which don’t result in as robust of skeletal strength overall.

Do ball sports help protect against stress fractures?

The last question to address is whether experience playing ball sports actually grants a protective effect from stress fractures in runners.  Fortunately, this exact concern was addressed in a large study of elite track and field athletes at the 2003 USATF national track championships, held at Stanford University.

Michael Fredericson, Jessica Ngo, and Kristin Cobb issued a one-page questionnaire to 156 female and 118 male distance runners competing at USATF nationals.  The athletes were asked about their sports histories and any stress fractures they had suffered.  After collecting the surveys, Fredericson, Ngo, and Cobb found that runners who had formerly been ball sport athletes had a significantly lower risk of suffering stress fractures.

For both men and women, each year of playing ball sports resulted in a 13% lower incidence of stress fractures.

Women, however, had one caveat: this protective effect only applied if they had normal menstrual periods; women with amenorrhea, which disturbs bone growth, had no protective effect from playing a ball sport like basketball or soccer.

Like with the two previous studies, the authors hypothesized that the diverse stresses associated with dynamic sports like soccer and basketball led to “greater and more symmetrically distributed bone mass,” which resulted in resistance to stress fractures.

Now, there’s still no research on whether playing ball sports while you’re also doing running training will grant any protective effects against injury, and as mentioned earlier, ball sports are far from innocuous.  Soccer and basketball players suffer a lot more ankle and knee sprains than runners do, for example.  But perhaps it is time to start thinking more seriously about the importance of general athleticism in running.

When you spend an hour a day or more running in mostly a straight line, you’re bound to develop some deficiencies when it comes to lateral or diagonal movement, as well as sharp accelerations and large stresses on your bones. 

Incorporating some agility drills or strength work into your running routine might be one way to address this; indeed, many elite runners already do strength and conditioning work that involves lateral shuffling, hurdle drills, medicine ball work, plyometric jumps, and diagonal running and cutting, all of which are similar to the types of stress involved with playing a ball sport.

Given what we’ve learned above, this type of ancillary training is likely to benefit your body’s overall structural integrity, hopefully leading to protection against stress fractures and possibly other overuse injuries too.