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, 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.

Low Back and Hip Pain in a Postpartum Runner: Applying Ultrasound Imaging and Running Analysis

“…15 For example, a 10% reduction in stride length can reduce the mechanical energy absorbed by the lower extremities by approximately 20%, thereby decreasing the load imparted on the lower extremities. 16 Thus, the physical demands of running can be reduced, which may prove beneficial in returning to running without symptom provocation. Similar efforts of gait retraining have been helpful in reducing symptoms of other running-related injuries such as iliotibial band syndrome or patellofemoral pain.…”

“…Specifically, it was concluded that her heel-strike landing in near knee extension was causing greater mechanical loading during landing, and contributing to her excessive pelvic motion. 16 Near the baseline assessment, an attempt was made to reduce the mechanical loading to the body during running by increasing the step rate from 168 to 185 steps per minute, necessitating a proportional decrease in stride length, assuming that her running speed remained constant. At the 7-week posttreatment follow-up, the patient demonstrated the increased step rate (192 steps per minute) without cuing, suggesting that she had successfully learned the new running form.…”

“…This decrease in energy absorption is most evident at the knee and hip, reflective of less work required of the more proximal joints. 16 Although the lumbar spine was not directly assessed, it is reasonable that decreased load in the lower extremities would be associated with decreased load in the lumbar spine. The reduced motion and mechanical loading likely contributed to improvement in clinical outcomes, such as symptom reduction and increased running distance, observed within days of starting the intervention.…”

“…Based on these observations, the patient was advised to reduce her running stride length by 10%, as an initial strategy to reduce the mechanical load to her body. 16 This was immediately achieved during the session by having the patient run at her preferred speed, while temporally matching her foot strikes to an audio metronome set to 185 beats per minute. The patient was also instructed in a running program designed by the primary physical therapist, which emphasized a slow progression of distance of approximately 10% per week.…”

“…16 In brief, whole-body kinematics were recorded (200 Hz) synchronously with ground reaction forces (2000 Hz) while the patient ran at her preferred speed (2.68 m/s) on a treadmill. The body was modeled as a 14-segment, 31-degrees-of-freedom articulated linkage.…”