Fatigue Responses during Repeated Sprints Matched for Initial Mechanical Output

School of Human Movement and Exercise Science, The University of Western Australia, Perth, Australia.
Medicine & Science in Sports & Exercise (Impact Factor: 3.98). 12/2007; 39(12):2219-25. DOI: 10.1249/mss.0b013e31815669dc
Source: PubMed


To compare muscle fatigability during two sets of repeated cycling sprints matched for initial mechanical output in a nonfatigued and fatigued state.
Eight young men performed 10, 6-s all-out sprints on a cycle ergometer interspersed with 30 s of recovery, followed, after 6 min of passive recovery, by five 6-s sprints, again interspersed by 30 s of recovery.
On the basis of total work (TW), performance in sprint 11 (79.8 +/- 4.8 was not significantly different to performance in sprint 4 (80.3 +/- 5.3; P = 0.81). The decrease in TW for the five sprints after sprint 4 (i.e., sprints 4 to 8) averaged 14.5% (P < 0.001), which was significantly less than the decrement in TW from sprints 11 to 15 (20.3%; P < 0.05). Despite no significant differences in TW values achieved in sprints 4 and 11, the amplitude of the electromyogram (EMG) signal (i.e., root mean square (RMS)) recorded during sprint 11 (0.398 +/- 0.03 V) was 12.0% lower (P < 0.05) than in sprint 4 (0.452 +/- 0.02 V). In contrast, values of EMG median frequency (MF) recorded during sprint 4 (85.5 +/- 5.5 Hz) and 11 (89.3 +/- 7.2 Hz) were not significantly different (P = 0.33). However, the rate of decrease in EMG activity (i.e., RMS and MF) was similar for the two set of sprints.
These findings suggest that previous fatiguing repeated-sprint exercise, followed by a rest period, induces greater fatigability during subsequent repeated-sprint exercise, regardless of the initial mechanical output, and that these changes are associated with acute neuromuscular adjustments.

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Available from: David John Bishop, Aug 06, 2014
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    • "To delineate the neural and muscular factors driving performance recovery following repeated sprints a sprint-matching paradigm was introduced, where exercise responses during two sets of repeated cycling sprints (10 x 6-s 'all out' sprints with 30 s recovery followed after 6 min of passive recovery by five 6-s sprints), matched for initial mechanical output in a 'non fatigued' (sprints 4 to 8) and a 'fatigued' state (sprints 11 to 15), were actually compared (Mendez-Villanueva et al. 2007). Results indicated that there was a greater fatigability in the five repetitions of the second versus first set, despite mechanical output produced for the initial bout of both sets (i.e., sprints 4 and 11) being similar. "

    Full-text · Article · Jan 2015 · Frontiers in Physiology
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    • "This suggests a link between peripheral perturbations and the regulation of muscle recruitment. The succession of efforts and incomplete recovery that characterises RSE typically induces large metabolic perturbations within active muscles [12,13], and results in large decrements in mechanical indices from the initial to the last sprint during prolonged protocols (e.g., >25% reduction in mechanical work with 10+ sprints) [14-17]. However, few studies have examined the regulation of muscle recruitment during RSE [12]. "
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    ABSTRACT: To investigate the interaction between the development of peripheral locomotor muscle fatigue, muscle recruitment and performance during repeated-sprint exercise (RSE). In a single-blind, randomised and cross-over design, ten male team-sport athletes performed two RSE (fifteen 5-s cycling sprints interspersed with 25 s of rest; power self-selected) in normoxia and in acute moderate hypoxia (FIO2 0.138). Mechanical work, total electromyographic intensity (summed quadriceps electromyograms, RMSsum) and muscle (vastus lateralis) and pre-fontal cortex near-infrared spectroscopy (NIRS) parameters were calculated for every sprint. Blood lactate concentration ([Lac(-)]) was measured throughout the protocol. Peripheral quadriceps fatigue was assessed via changes in potentiated quadriceps twitch force (ΔQtw,pot) pre- versus post-exercise in response to supra-maximal magnetic femoral nerve stimulation. The central activation ratio (QCAR) was used to quantify completeness of quadriceps activation. Compared with normoxia, hypoxia reduced arterial oxygen saturation (-13.7%, P=0.001), quadriceps RMSsum (-13.7%, P=0.022), QCAR (-3.3%, P=0.041) and total mechanical work (-8.3%, P=0.019). However, the magnitude of quadriceps fatigue induced by RSE was similar in the two conditions (ΔQtw,pot: -53.5% and -55.1%, P=0.71). The lower cycling performance in hypoxia occurred despite similar metabolic (muscle NIRS parameters and blood [Lac(-)]) and functional (twitch and M-wave) muscle states. Results suggest that the central nervous system regulates quadriceps muscle recruitment and, thereby, performance to limit the development of muscle fatigue during intermittent, short sprints. This finding highlights the complex interaction between muscular perturbations and neural adjustments during sprint exercise, and further supports the presence of pacing during intermittent sprint exercise.
    Full-text · Article · Dec 2013 · PLoS ONE
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    • "However, it is well-known that the greater the initial force exerted by a muscle during a given task, the more the muscle will fatigue (Enoka and Stuart 1992; Hunter 2009). Thus, it is not surprising to observe that the higher the initial-sprint performance , the larger the performance decrement in subsequent sprint repetitions (Bishop et al. 2003b; Bishop and Spencer 2004; Gaitanos et al. 1993; Mendez-Villanueva et al. 2007, 2008). This is supported by our observation (Fig. 2 "
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    ABSTRACT: To investigate whether the larger reduction in mechanical work observed during repeated-sprint exercise (RSE) in men versus women represents a true, physiological sex dimorphism or is the consequence of the higher initial mechanical work performed by men. Male and female team-sport athletes (n = 35) performed 20, 5-s cycle sprints interspersed with 25 s of rest. Mechanical work and surface electromyograms (EMG) of four muscles were recorded in every sprint. Mechanical work achieved in one sprint (20.7%, P = 0.0006), total work accumulated over the 20 sprints (21.1%, P = 0.009) and percent work decrement (32.2%, P = 0.008) were larger in men than in women. When both sexes were plotted together, there was a positive relationship between the initial-sprint work and the work decrement across sprint repetitions (r = 0.89, P = 0.002). The RSE induced larger (P = 0.009) absolute EMG amplitude changes in men (-155.2 ± 60.3 mVs) than in women (-102.5 ± 45.1 mVs). Interestingly, in a subset of men and women (n = 7 per group) matched for initial-sprint work, the sex difference in percent work decrement (men: -29.5 ± 1.5%; women: -27.2 ± 3.2%; P = 0.72) and EMG changes (men: -17.7 ± 6.9% vs. women: -15.3 ± 7.1%; P = 0.69) no longer persisted. Results show that the proposed greater fatigue in men is likely to be a consequence of their greater absolute initial-sprint performance, rather than a sex difference in fatigue resistance per se. We conclude that, on the basis of the absolute mechanical work completed, women are not more fatigue resistant than men and use comparable muscle recruitment strategies to perform RSE.
    Full-text · Article · Aug 2011 · Arbeitsphysiologie
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