Effects of 12-week cadence retraining on impact peak, load rates and lower extremity biomechanics in running

Junqing Wang; Zhen Luo; Boyi Dai; Weijie Fu

doi:10.7717/peerj.9813

Effects of 12-week cadence retraining on impact peak, load rates and lower extremity biomechanics in running

PeerJ. 2020 Aug 24:8:e9813. doi: 10.7717/peerj.9813. eCollection 2020.

Authors

Junqing Wang¹, Zhen Luo¹, Boyi Dai², Weijie Fu^{1

3}

Affiliations

¹ School of Kinesiology, Shanghai University of Sport, Shanghai, China.
² Division of Kinesiology and Health, University of Wyoming, Laramie, WY, USA.
³ Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport, Shanghai, China.

Abstract

Background: Excessive impact peak forces and vertical load rates are associated with running injuries and have been targeted in gait retraining studies. This study aimed to determine the effects of 12-week cadence retraining on impact peak, vertical load rates and lower extremity biomechanics during running.

Methods: Twenty-four healthy male recreational runners were randomised into either a 12-week cadence retraining group (n = 12), which included those who ran with a 7.5% increase in preferred cadence, or a control group (n = 12), which included those who ran without any changes in cadence. Kinematics and ground reaction forces were recorded simultaneously to quantify impact force variables and lower extremity kinematics and kinetics.

Results: Significantly decreased impact peak (1.86 ± 0.30 BW vs. 1.67 ± 0.27 BW, P = 0.003), vertical average load rates (91.59 ± 18.91 BW/s vs. 77.31 ± 15.12 BW/s, P = 0.001) and vertical instantaneous load rates (108.8 ± 24.5 BW/s vs. 92.8 ± 18.5 BW/s, P = 0.001) were observed in the cadence retraining group, while no significant differences were observed in the control group. Foot angles (18.27° ± 5.59° vs. 13.74° ± 2.82°, P = 0.003) and vertical velocities of the centre of gravity (CoG) (0.706 ± 0.115 m/s vs. 0.652 ± 0.091 m/s, P = 0.002) significantly decreased in the cadence retraining group at initial contact, but not in the control group. In addition, vertical excursions of the CoG (0.077 ± 0.01 m vs. 0.069 ± 0.008 m, P = 0.002) and peak knee flexion angles (38.6° ± 5.0° vs. 36.5° ± 5.5°, P < 0.001) significantly decreased whilst lower extremity stiffness significantly increased (34.34 ± 7.08 kN/m vs. 38.61 ± 6.51 kN/m, P = 0.048) in the cadence retraining group. However, no significant differences were observed for those variables in the control group.

Conclusion: Twelve-week cadence retraining significantly increased the cadence of the cadence retraining group by 5.7%. This increased cadence effectively reduced impact peak and vertical average/instantaneous load rates. Given the close relationship between impact force variables and running injuries, increasing the cadence as a retraining method may potentially reduce the risk of impact-related running injuries.

Keywords: Cadence; Impact peak; Lower extremity biomechanics; Running.

Grants and funding

This work was supported by the National Natural Science Foundation of China (11772201 and 11932013), National Key Research and Development Program of China (2019YFF0302100), the “Dawn” Program of Shanghai Education Commission (19SG47), the Talent Development Fund of Shanghai Municipal (2018107), Scientific Research Program of Shanghai Administration of Sports (20Q004), and the High-Level Internationalized Talents Program of Shanghai University of Sport. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.