Article #14 of 50: I have made it a goal of mine to share at least 50 research articles with you to review in 2012. These articles will be shared with no opinion of mine, just purely the information provided in the research and where to go to read more about the topic. This weekly challenge will feature many different aspects of the field: strength, conditioning, nutrition, psychology, etc. If you would like to submit research articles to be included in this segment, please email me a PDF version of the peer reviewed journal article.
Med. Sci. Sports Exerc., Vol. 43, No. 2, pp. 296-302, 2011.
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, whereas 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), braking 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) and 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.