TY - JOUR

T1 - Monitoring muscle fatigue progression during dynamic exercise

AU - Rannou, Fabrice

AU - Nybo, Lars

AU - Andersen, Janni Enghave

AU - Nordsborg, Nikolai B

N1 - CURIS 2019 NEXS 206

PY - 2019

Y1 - 2019

N2 - Purpose: To develop and validate a novel model for assessment of peripheral fatigue progression during dynamic exercise.Methods: Seven males and four females (24 ± 3 yrs) completed one-legged knee-extensor exercise at 40% of peak power output for 12 min (40%PPO). Additionally, an exhaustive bout lasting ~ 6 min (84 ± 2% PPO; 59 ± 10 watt) was contrasted to two bouts completed at ± 5% of the target workload. Trials were completed in randomized order. Percutaneous electrical stimulation of m. vastus lateralis during the passive knee-flexion phase allowed quantification of maximal twitch force every 30 s in parallel with rating of perceived exertion (RPE).Results: Elicited twitch force remained unchanged during the 40%PPO trial. During the three exhaustive bouts, exercise differed in duration (561 ± 154 s, 366 ± 64 s, 245 ± 61 s; P < 0.001) and amplitude of elicited twitch force showed a curvilinear decline across time. Elicited twitch force at exhaustion was ~60% reduced and similar between the exhaustive trials (ICC = 0.76 [0.48 - 0.92, 95% CI]). The increase in RPE during exercise was strongly correlated to the gradually reduced evoked twitch force (repeated measures correlation = 0.89 [0.62 - 0.97, 95% CI]).Conclusion: The developed model permits quantification of muscle fatigue progression during continuous dynamic one-legged knee-extension and a bi-phasic fatigue pattern is demonstrated during intense exercise. The model is sensitive to small changes in intensity and it provides a novel approach for studying muscular mechanisms and their temporal relation to fatigue progression in vivo.

AB - Purpose: To develop and validate a novel model for assessment of peripheral fatigue progression during dynamic exercise.Methods: Seven males and four females (24 ± 3 yrs) completed one-legged knee-extensor exercise at 40% of peak power output for 12 min (40%PPO). Additionally, an exhaustive bout lasting ~ 6 min (84 ± 2% PPO; 59 ± 10 watt) was contrasted to two bouts completed at ± 5% of the target workload. Trials were completed in randomized order. Percutaneous electrical stimulation of m. vastus lateralis during the passive knee-flexion phase allowed quantification of maximal twitch force every 30 s in parallel with rating of perceived exertion (RPE).Results: Elicited twitch force remained unchanged during the 40%PPO trial. During the three exhaustive bouts, exercise differed in duration (561 ± 154 s, 366 ± 64 s, 245 ± 61 s; P < 0.001) and amplitude of elicited twitch force showed a curvilinear decline across time. Elicited twitch force at exhaustion was ~60% reduced and similar between the exhaustive trials (ICC = 0.76 [0.48 - 0.92, 95% CI]). The increase in RPE during exercise was strongly correlated to the gradually reduced evoked twitch force (repeated measures correlation = 0.89 [0.62 - 0.97, 95% CI]).Conclusion: The developed model permits quantification of muscle fatigue progression during continuous dynamic one-legged knee-extension and a bi-phasic fatigue pattern is demonstrated during intense exercise. The model is sensitive to small changes in intensity and it provides a novel approach for studying muscular mechanisms and their temporal relation to fatigue progression in vivo.

KW - Faculty of Science

KW - Dynamic exercise

KW - Exhaustion

KW - Intensity

KW - Muscle fatigue

KW - One-legged knee-extension

KW - Twitch

U2 - 10.1249/MSS.0000000000001921

DO - 10.1249/MSS.0000000000001921

M3 - Journal article

C2 - 30741747

VL - 51

SP - 1498

EP - 1505

JO - Medicine and Science in Sports and Exercise

JF - Medicine and Science in Sports and Exercise

SN - 0195-9131

IS - 7

ER -