Speed is achieved through stride rate and stride frequency. The goal is to optimize the both forces but there is a trade off as the stride length is increased resulting in increased air time . . . what goes up, must come down. Both factors are critical but I've diving into studies comparing the 2 forces as they may relate to injury prevention.
As I think back to when I started barefoot running, I listened to Barefoot Ken Bob, BFT and others talk about shorter strides and it occurs naturally when barefoot. You can still have a good stride length barefoot but generally you can't fly through the air and over- stride the way you can do in shoes.
Here's one of many studies I'm reading:
Abstract
Purpose: The objective of this study was to characterize the biomechanical effects of step rate modification during running on the hip, knee and ankle joints, so as to evaluate a potential strategy to reduce lower extremity loading and risk for injury.
Methods: Three-dimensional kinematics and kinetics were recorded from 45 healthy recreational runners during treadmill running at constant speed under various step rate conditions (preferred, +/- 5% and +/- 10%). We tested our primary hypothesis that a reduction in energy absorption by the lower extremity joints during the loading response would occur, primarily at the knee, when step rate was increased.
Results: Less mechanical energy was absorbed at the knee (p<0.01) during the +5% and +10% step rate conditions, while the hip (p<0.01) absorbed less energy during the +10% condition only. All joints displayed substantially (p<0.01) more energy absorption when preferred step rate was reduced by 10. Step length (p<0.01), center of mass vertical excursion (p<0.01), breaking impulse (p<0.01) and peak knee flexion angle (p<0.01) were observed to decrease with increasing step rate. When step rate was increased 10% above preferred, peak hip adduction angle (p<0.01), as well as peak hip adduction (p<0.01) and internal rotation (p<0.01) moments, were found to decrease.
Conclusion: We conclude that subtle increases in step rate can substantially reduce the loading to the hip and knee joints during running and may prove beneficial in the prevention and treatment of common running-related injuries.
HHH
Thursday, November 18, 2010
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment