Effects of level running-induced fatigue on running kinematics: A systematic review and meta-analysis.

BACKGROUND: Runners have a high risk of acquiring a running-related injury. Understanding the mechanisms of impact force attenuation into the body when a runner fatigues might give insight into the role of running kinematics on the aetiology of overuse injuries. RESEARCH QUESTIONS: How do running kinematics change due to running-induced fatigue? And what is the influence of experience level on changes in running kinematics due to fatigue? METHODS: Three electronic databases were searched: PubMed, Web of Science, and Scopus. This resulted in 33 articles and 19 kinematic quantities being included in this review. A quality assessment was performed on all included articles and meta-analyses were performed for 18 kinematic quantities. RESULTS AND SIGNIFICANCE: Main findings included an increase in peak acceleration at the tibia and a decrease in leg stiffness after a fatiguing protocol. Additionally, level running-induced fatigue increased knee flexion at initial contact and maximum knee flexion during swing. An increase in vertical centre of mass displacement was found in novice but not in experienced runners with fatigue. Overall, runners changed their gait pattern due to fatigue by moving to a smoother gait pattern (i.e. more knee flexion at initial contact and during swing, decreased leg stiffness). However, these changes were not sufficient to prevent an increase in peak accelerations at the tibia after a fatigue protocol. Large inter-individual differences in responses to fatigue were reported. Hence, it is recommended to investigate changes in running kinematics as a result of fatigue on a subject-specific level since group-level analysis might mask individual responses.

Outdoor E-trike cycling: A low intensity physical activity.

For people with disabilities or chronic diseases, an electrically supported tricycle (e-trike) could facilitate independence and participation in physical activity, and improve health conditions. This study investigates the exercise intensity and perceived exertion of e-trike cycling. Twenty healthy participants cycled on an e-trike with different speeds (12 and 18 km/h) and different levels of electric pedal support at an outdoor athletics track. Exercise intensity was measured with oxygen consumption (V˙O2) using a Cosmed K4B2 analysis unit, perceived exertion was measured with the Borg Rating of Perceived Exertion scale, pedaling power, and engine power were measured with a torque sensor. The effect of speed and support was analyzed with a Linear Mixed Effects model. V˙O2 was 18.67 ± 3.13 ml/kg/min without support, with electric support the exercise intensity was significantly below moderate intensity (i.e. 10.5 ml/kg/min) at t = 11.37, p < .001, 95% CI: 1.90, 2.77. The Borg score without support was 9.79 ± 1.72 and all other conditions below this, which were significantly below moderate intensity (i.e. 11) at t = -3.07, p = .007, 95% CI: -2.04, -0.38. Speed and support significantly affected V˙O2 (F = 185.49, p < .001). E-trike cycling is a low intensity activity, but intensity can be influenced by changing speed and support level.