Effects of step rate manipulation on joint mechanics during running

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, 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.

Conflict of interest statement

Conflict of Interest: The authors have no conflicts of interest.

Figures

Figure 1

Center of mass (COM) vertical excursion, horizontal distance from COM to heel at initial contact and foot inclination at initial contact decreased as step rate increased.

Figure 2

At the hip and knee joints, energy absorption (negative work) and generation (positive work) were observed to decrease with increasing step rate. The ankle joint displayed a reduction in energy generation with step rate, while energy absorption remained relatively consistent. Negative work was determined during loading response (defined as foot contact to peak knee flexion angle) and positive work was determined throughout stance phase. Data are from a representative subject.

Figure 3

While the knee joint showed the greatest absolute change in mechanical energy absorption with step rate, the hip joint showed the greatest percent change. Despite the overall reduction in mechanical energy absorption across joints at the higher step rate conditions, the ankle joint was responsible for a greater proportion. The mechanical energy generated by each joint during stance phase remained proportional across the step rate conditions. All data are reported as a percentage of the preferred condition.