Diurnal Variation in Wingate-Test Performance and Associated Electromyographic Parameters

Abstract

The present study was designed to evaluate time-of-day effects on electromyographic (EMG) activity changes during a short-term intense cycling exercise. In a randomized order, 22 male subjects were asked to perform a 30-s Wingate test against a constant braking load of 0.087 kg·kg(-1) body mass during two experimental sessions, which were set up either at 07:00 or 17:00 h. During the test, peak power (P(peak)), mean power (P(mean)), fatigue index (FI; % of decrease in power output throughout the 30 s), and evolution of power output (5-s span) throughout the exercise were analyzed. Surface EMG activity was recorded in both the vastus lateralis and vastus medialis muscles throughout the test and analyzed over a 5-s span. The root mean square (RMS) and mean power frequency (MPF) of EMG were calculated. Neuromuscular efficiency (NME) was estimated from the ratio of power to RMS. Resting core temperature, P(peak), P(mean), and FI were significantly higher (p < .05) in the evening than morning test (e.g., P(peak): 11.6 ± 0.8 vs. 11.9 ± 1 W·kg(-1)). The results showed that power output decreased following two phases. During the first phase (first 20s), power output decreased rapidly and values were higher (p < .05) in the evening than in the morning. During the second phase (last 10s), power decreased slightly and appeared independent of the time of day of testing. This power output decrease was paralleled by evolution of the MPF and NME. During the first phase, NME and MPF were higher (p < .05) in the evening. During the second phase, NME and MPF were independent of time of day. In addition, no significant differences were noticed between 7:00 and 17:00 h for EMG RMS during the whole 30 s. Taken together, these results suggest that peripheral mechanisms (i.e., muscle power and fatigue) are more likely the cause of the diurnal variation of the Wingate-test performance rather than central mechanisms.

The effect of time-of-day and judo match on short-term maximal performances in judokas

“…Concerning the time-of-day effect on short-term anaerobic performances, the present study's findings were in agreement with previous data that have clearly demonstrated a significant diurnal variation in anaerobic performances in adults (Chtourou, Zarrouk et al 2011;Hammouda et al 2011;Abedelmalek, Chtourou, Aloui, Aouichaoui et al 2012;Aloui, Chtourou, Masmoudi et al 2012;Hamouda et al 2012;Souissi, Chtourou, Hdidar, et al 2012) or youth subjects (Souissi, Chaouachi et al 2010;. In this regard, the effect of time-of-day short-term maximal performances during continuous (e.g.…”

“…Indeed, although Souissi et al (2007) showed higher decrease in power output in the morning compared to the evening during the Wingate test, Lericollais et al (2010) and Chtourou, Zarrouk et al (2011) observed that muscle fatigue (i.e. decrease in power output throughout the Wingate test) was higher in the evening than the morning.…”

“…Actually, previous studies reported a significant time-of-day effect on resting biochemical parameters (Hammouda, Chtourou, Chaouachi et al in press) and both physical and psychological performances (Jarraya, Jarraya et al 2012;Souissi, Chtourou, Zouita et al 2012). The effect of time-of-day on short-term maximal anaerobic performance has been demonstrated for various tasks such as the Wingate test (Souissi et al 2004;Chtourou, Zarrouk et al 2011;, the repeated sprint ability test Aloui, Chtourou, Masmoudii et al 2012;, the vertical jump tests , the hand grip (HG) test (Souissi, Chaouachi et al 2010), and the maximal voluntary contraction test (Aloui, Chaouachi, Chtourou et al in press;. For example, during the Wingate test, Souissi et al (2004) reported that peak power (PP) and mean power (MP) fluctuate with time-of-day, with morning nadirs, afternoon/early evening peak values, and an amplitude of 7.6 ± 0.8% and 11.3 ± 1.1% for PP and MP, respectively.…”

“…Indeed, the diurnal increase in body temperature may exert a beneficial passive warm-up that may enhance metabolic reactions, increase the extensibility of connective tissue, reduce muscle viscosity, and increase conduction velocity of action potentials (Souissi et al 2004). Thus, some authors have suggested that the diurnal variations in maximal short-term performances are linked to peripheral mechanisms, rather than variation in central nervous command (Chtourou, Zarrouk et al 2011;). For instance, previous studies reported an increase in muscle power during the Wingate test (Chtourou, Zarrouk et al 2011) and the repeated sprint ability test in the evening compared to the morning without any proportional increase in muscles' electromyographic activities.…”

Time-of-day effects on postural control and attentional capacities in children

“…Thus, increased core temperature due to circadian patterns would facilitate enhancement of the neuromuscular and metabolic systems [46] which may improve the efficiency of postural muscle activity to control children's balance. It has been established that the cause of the child's diurnal variations of muscle power and fatigue during a short-term maximal performance was related to peripheral mechanisms [47] through an improvement of the muscle contractile properties at the end of the day as reported in young adults [48][49][50].…”