A couple simple stride tweaks may reduce injury risk.
Some runners land harder than others—even when body weight and speed (which actually has a greater effect on impact forces than body weight)—are held constant. Past research has shown that runners who land harder get injured more often. Two published studies provide evidence that runners can make simple changes to soften their landing when they run and thereby potentially reduce their injury risk.
Overstriding is commonly associated with excessive impact. Overstriding consists in touching the foot to the ground heel-first well ahead of the hips. Runners who overstride take fewer steps per minute at a given running speed than runners who do not overstride. Researchers at the University of Wisconsin recently investigated whether they could reduce impact forces in runners by increasing their stride rate.
The researchers measured various kinetic and kinematic variables in runners as they ran at their preferred stride rate and at stride rates 5 and 10 percent greater and less than the preferred. They found that when runners increased their stride rate by 10 percent they exhibited a significantly reduced tendency to overstride and a significant reduction in impact forces.
You can try this at home by counting the number of strides you take in one minute when running normally, then fiddling with your stride to get a 10 percent increase. It will feel funny at first but may become more natural over time if you consistently enforce your new strides-per-minute target.
Another study on the effects of stride manipulations on injury–related factors appears in the British Journal of Sports Medicine. In this study, researchers at the universities of Kentucky and Delaware trained runners suffering from patellofemoral pain syndrome (PFPS) to reduce a tendency to collapse at the hip during the stance phase of the stride, a biomechanical flaw that is associated with PFPS risk. The researchers used biofeedback to teach the runners to prevent the unsupported side of the pelvis from dropping in the stance phase over eight sessions. They then let the runners loose into the world to train on their own for one month. Finally, they brought the runners back to see if the changes had stuck and to assess changes in their levels of pain and function.
The gait retraining appeared to work, producing measurable changes in hip mechanics that lasted through the month of unsupervised running. There were also significant improvements in pain levels and function, although there was no control group so we can’t rule out the possibility that these improvements would have occurred anyway.
Unexpectedly, the researchers found that the changes to the subjects’ strides also yielded significant reductions in impact forces. It appears that the specific intent to run without pelvic tilting resulted in global changes that affected impact forces.
You can try this one at home by concentrating on squeezing your right buttock the instant before your right foot touches the ground when you run, and doing the same on the left side. As with the increase in stride rate described above, this one cannot be made permanent unless you do it consciously on every stride until it starts to happen automatically, which could take a few weeks.