Energetically optimal stride frequency is maintained with fatigue in trained ultramarathon runners

TY - JOUR

T1 - Energetically optimal stride frequency is maintained with fatigue in trained ultramarathon runners

AU - Vernillo, Gianluca

AU - Doucende, Gregory

AU - Cassirame, J.

AU - Mourot, Laurent

PY - 2019/9/1

Y1 - 2019/9/1

N2 - Objectives: At a given running speed, humans naturally endeavor to achieve an optimal stride frequency that minimizes metabolic cost. Research has suggested that runners select this near optimal stride frequency in some process of self-optimization even during fatiguing tasks up to 1-h of high-intensity running. Here, we studied whether runners demonstrate a similar self-optimizing capability after an ultramarathon of 6 h. Design: Controlled pre-post study. Method: We collected temporal stride kinematics and metabolic data in nine (experimental group) male runners before and after 6 h of running and in six (control group) male ultramarathon runners who did not run, but stayed awake and performed normal, daily physical activities avoiding strenuous exercises over the 6-h period. For each participant, preferred and optimal stride frequencies were measured, where stride frequency was systematically varied above and below PSF (±4% and ±8%). Results: Preferred and optimal stride frequencies across time and group showed no significant differences (p ≥ 0.276). Furthermore, neither the overall relationship between metabolic cost and stride frequency, nor the energetically optimal stride frequency changed substantially after several hours of running. Conclusions: Similar dynamics of stride frequency adjustments in the experimental group occurred as those found in a non-fatigued state. This suggests that after an ultramarathon of 6 h, runners were still able to optimize their gait, and automatically adjust it in order to converge on the energetically optimal gait.

AB - Objectives: At a given running speed, humans naturally endeavor to achieve an optimal stride frequency that minimizes metabolic cost. Research has suggested that runners select this near optimal stride frequency in some process of self-optimization even during fatiguing tasks up to 1-h of high-intensity running. Here, we studied whether runners demonstrate a similar self-optimizing capability after an ultramarathon of 6 h. Design: Controlled pre-post study. Method: We collected temporal stride kinematics and metabolic data in nine (experimental group) male runners before and after 6 h of running and in six (control group) male ultramarathon runners who did not run, but stayed awake and performed normal, daily physical activities avoiding strenuous exercises over the 6-h period. For each participant, preferred and optimal stride frequencies were measured, where stride frequency was systematically varied above and below PSF (±4% and ±8%). Results: Preferred and optimal stride frequencies across time and group showed no significant differences (p ≥ 0.276). Furthermore, neither the overall relationship between metabolic cost and stride frequency, nor the energetically optimal stride frequency changed substantially after several hours of running. Conclusions: Similar dynamics of stride frequency adjustments in the experimental group occurred as those found in a non-fatigued state. This suggests that after an ultramarathon of 6 h, runners were still able to optimize their gait, and automatically adjust it in order to converge on the energetically optimal gait.

KW - Gait

KW - Metabolic cost

KW - Optimization

KW - Ultraendurance

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U2 - 10.1016/j.jsams.2019.04.003

DO - 10.1016/j.jsams.2019.04.003

M3 - Article

C2 - 31029549

AN - SCOPUS:85064708600

VL - 22

SP - 1054

EP - 1058

JO - Journal of Science and Medicine in Sport

JF - Journal of Science and Medicine in Sport

SN - 1440-2440

IS - 9

ER -