A new study published online in Medicine & Science in Sports & Exercise, the journal of the American College of Sports Medicine, found that runners who strike the ground with their forefoot in a toe-heel movement are less injury-prone than those with a rearfoot motion.
The retrospective study looked at differences in injury types and rates. Analysis was based on four years’ worth of data from Harvard University’s men’s and women’s cross country running teams – information about their daily mileage, pace, and injuries, entered into an online training website managed by athletic trainers and coaches.
Different Foot Forms
Three “strike types” (how a runner’s foot strikes the ground) were identified: 1) rearfoot or heel strikes, in which the heel contacts the ground first (heel-toe running); 2) forefoot strikes, in which the ball of the foot contacts the ground before the heel (toe-heel-toe running); and, less commonly, 3) midfoot strikes, in which the heel and ball of the foot contact the ground simultaneously.
While most people are not exclusively heel or forefoot strikers, with differences occurring due to factors such as surface incline, speed, and fatigue, runners tend to favor one form over the other.
Of the 52 Harvard runners who were studied, 69% (36 runners) were heel strikers, and only 16, or 31%, were forefoot strikers. Proportions were similar across gender and distance covered (middle versus long-distance).
Injury Types & Rates
While most of the runners, regardless of strike type, reported some form of injury, 74% experienced moderate to severe injuries which prevented them from participating in running for two or more days. And just as researchers predicted, the distribution of injuries showed heel strikers to be more injury-prone.
The most common injuries were muscle strains (21.5% of all injuries), medial tibial stress syndrome, more commonly known as shin splints (13.8%), knee pain (7.7%), illiotibial band syndrome (7.2%) and Achilles tendinopathies (6.6%). When compared to forefoot strikers, heel strikers were nearly twice as likely to sustain moderate and severe repetitive stress injuries and 2.5 times more likely to experience mild and moderate injuries.
Shoes, which many runners changed every day, did not affect the results. Neither well-cushioned shoes nor minimal racing flats prevented injuries in either group.
Lead author Adam I. Daoud notes, “Most important from the perspective of injury is the nature of the impact peak measured in the vertical ground reaction force just after contact between the foot and the ground.” Heel strikers generate a higher impact, applying greater force to the lower half of the body. These forces are “potentially injurious in skeletal tissues, especially bone, because they increase hysteresis, which leads to structural damage that can accumulate over repeated events.”
So should we all convert to forefoot striking? While something to consider, especially if one seems to be injury-prone, researchers acknowledge that there are many heel strike runners who rarely, if ever, get injured. These runners may have better running form, may land with less overstride and may have more compliant limbs that reduce stress on the joints. They may also have fewer physical abnormalities that would make them more inclined to injury.
If you do decide to switch, do so gradually, warns Daoud. Because forefoot striking requires stronger foot muscles, too rapid a change may result in calf muscle strains, forefoot pain, Achilles tendinopathies, or stress fractures. Runners should transition “slowly, gradually, and with good overall form.”
The Bottom Line
With any physical activity, preventing injury should always be a priority. But as this study shows, both runners and researchers can gain greater understanding about the nature of injuries and how to reduce risk by paying attention to how people run and maintaining proper form.
Of course, some injuries are the result of our physical makeup. A study in the Journal of Bone and Joint Surgery shows that the incidence of anterior cruciate ligament (ACL) injuries may be explained by the length and shape of the knee bone. According to the study, those with shorter and more rounded tibial plateaus (the upper part of the shin bone which meets the joint), more common in women than men, are more likely to experience initial and recurrent ACL tears because of the inherent instability of the knee and ligament structures. While this study shows ACL injuries are more about geometry than gender, it also allows women to understand that they are more at risk for this particular injury and should take increased caution.
But fear of injury shouldn’t discourage us from increasing our physical activity. It’s well known that many of us do not get enough exercise, despite our increasing knowledge about its benefits. Even doctors tend to under-recommend exercise, advising only 1 in 3 people to exercise. They also tend to focus only on older or overweight individuals and those with heart disease, hypertension, cancer, or diabetes. So while talking about exercise is up from the previous decade, both the medical community and the community at large need to prioritize the need for more physical activity.
When we have knowledge about how to exercise and what to watch out for, the benefits of physical activity far outweigh the risks. Now get out, and get moving!