title: Exercise performance is regulated during repeated sprints to limit the development of peripheral fatigue beyond a critical threshold.
abstract: We hypothesized that exercise performance is adjusted during repeated sprints in order not to surpass a critical threshold of peripheral fatigue. Twelve men randomly performed three experimental sessions on different days, i.e. one single 10 s all-out sprint and two trials of 10 × 10 s all-out sprints with 30 s of passive recovery in between. One trial was performed in the unfatigued state (CTRL) and one following electrically induced quadriceps muscle fatigue (FTNMES). Peripheral fatigue was quantified by comparing pre- with postexercise changes in potentiated quadriceps twitch force (ΔQtw-pot) evoked by supramaximal magnetic stimulation of the femoral nerve. Central fatigue was estimated by comparing pre- with postexercise voluntary activation of quadriceps motor units. The root mean square (RMS) of the vastus lateralis and vastus medialis EMG normalized to maximal M-wave amplitude (RMS.Mmax (-1)) was also calculated during sprints. Compared with CTRL condition, pre-existing quadriceps muscle fatigue in FTNMES (ΔQtw-pot = -29 ± 4%) resulted in a significant (P < 0.05) reduction in power output (-4.0 ± 0.9%) associated with a reduction in RMS.Mmax (-1). However, ΔQtw-pot postsprints decreased by 51% in both conditions, indicating that the level of peripheral fatigue was identical and independent of the degree of pre-existing fatigue. Our findings show that power output and cycling EMG are adjusted during exercise in order to limit the development of peripheral fatigue beyond a constant threshold. We hypothesize that the contribution of peripheral fatigue to exercise limitation involves a reduction in central motor drive in addition to the impairment in muscular function.
authors.affiliation: University of Nice Sophia Antipolis, Toulon, LAMHESS, EA 6309, F-06205, Nice, France University of Lille Nord de France, F-59000, Lille, France; UDSL, EA 4488, F-59790, Ronchin, France.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Hureau
authors.affiliation: University of Lille Nord de France, F-59000, Lille, France; UDSL, EA 4488, F-59790, Ronchin, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Olivier
authors.affiliation: University of Lyon, F-42023, Saint Etienne, France University of Calgary, Faculty of Kinesiology, Human Performance Laboratory, Calgary, Alberta, Canada.
authors.forename: Guillaume Y
authors.initials: GY
authors.lastname: Millet
authors.affiliation: CNRS - University of Nice Sophia Antipolis, I3S, F-06900, Sophia Antipolis, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Meste
authors.affiliation: University of Nice Sophia Antipolis, Toulon, LAMHESS, EA 6309, F-06205, Nice, France University of Lille Nord de France, F-59000, Lille, France; UDSL, EA 4488, F-59790, Ronchin, France gregoryblain@ymail.com.
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Blain
mesh_terms: D000328:Adult; D004558:Electric Stimulation; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D005221:Fatigue / Q000503:physiopathology*; D005267:Femoral Nerve / Q000502:physiology; D006801:Humans; D008297:Male; D009119:Muscle Contraction; D018763:Muscle Fatigue / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology