Found on RunnersWorld.com and written by Amby Burfoot
Lower leg strength training might be the key to maintaining running speed over time.
It’s a running fact of life: Runners get slower as they get older. But a new report suggests that strengthening the ankles and calves could help aging runners stave off the slowdown.
A new Army-funded study conducted by researchers at East Carolina University and Wake Forest University, indicates that weakness in the ankles and calves can contribute to biomechanical stride changes that slow aging runners. Study authors concluded that masters runners might be able to run faster if they do more lower-leg strength and power training.
The older runners in the study maintained roughly the same stride frequency as their younger counterparts (about 165 strides/minute). But they suffered from significantly shorter strides, which reduced their speed.
The report revealed that stride length and running speed slowed by about 20 percent from age 20 to 59, and the loss of ankle power during this time frame was almost 48 percent. “Our research indicates that aging runners could perhaps maintain their speed through increased calf-muscle strength and power exercises,” one of the study authors, Paul DeVita, Ph.D., wrote in an email to Runner’s World Newswire. DeVita is president of the American Society of Biomechanics and director of the biomechanics lab at East Carolina University.
The new paper is the first running biomechanics paper to look at the measured variables across a wide age range of runners. Previous research bundled runners into just two buckets, young and old. DeVita and colleagues investigated the running biomechanics of 109 runners (58 men) from age 23 to age 59. The runners logged an average of 34 miles per week. To judge from their average BMIs, an average of 23.4, all were lean and highly fit.
DeVita says he was most surprised by the linear loss of speed shown by the runners. In other words, he expected that runners in their 50s might exhibit relatively more decline than those in their 30s and 40s. This didn’t turn out to be the case, though he speculates it might be true when the runners move into their 60s. Many 60- and 70-year-old runners will nod their heads affirmatively on this topic.
Researchers recruited runners in their 20s, 30s, 40s, and 50s, and had all of them run on an instrumented treadmill while filmed by high-speed video cameras. The subjects ran at their normal training pace. For a 20-year-old, this averaged 8:18 per mile. For a 60-year-old runner, 10:18 per mile. The decrease in pace was highly correlated with a shortening stride and loss of ankle power.
While the paper calls attention to the ankle joint, measuring many variables of ankle force and power production, DeVita acknowledges that it is actually the calf muscles—particularly the soleus and gastrocnemius muscles—that produce these forces. Since DeVita’s not a trained strength and conditioning coach, he hesitates to suggest exercises that could help runners maintain more ankle power. However, he noted that a combination of slow, heavy-weight strengthening workouts and faster, lower-weight power workouts for the lower leg should work well.
Of course, all new exercise regimens should be undertaken slowly and progressively. Unaccustomed ankle work could improve performance and injury-prevention, or could cause an injury, particularly in the case of aging runners who add something different to their routine. Devita understands this, noting, “One must be careful with any exercise, especially a new one. Anyone can overdo the amount of loading a tissue can take.”
The study authors were also impressed by the way the runners held their lean BMI through the decades.
“It appears that long-term running might be an effective non-pharmacologic weight maintenance intervention,” they wrote.