Efeitos do aquecimento muscular ativo sobre o desempenho de sprints repetidos em cicloergômetro em diferentes períodos do dia

Abstract

The diurnal variation in body temperature together with the changes provided by active warm up can influence short-term exercise performance. The aim of this study was to investigate the effect of muscle temperature and time-of-day on performance (maximum power, mean power, number of cycles and power reduction index) and physiological variablities during repeated sprints (SRs). Twelve volunteers performed 4 SRs, 2 in the morning (7:00 9:00) and 2 in the evening (17:00 -19:00) in a random order, interspersed by 72 hours. The SRs cycle consisted of 10 min of active warm up (50% of PMAX) followed by 10 sprints of 6 seconds interspersed by 30 sec of passive recovery and a total recovery period of 60 minutes. The PMAX, PMEAN and number of cycles developed in the 1st sprint were higher after active warm up compared with rest (5,8% 6,1% and 4,9%) and higher in the afternoon period compared with the morning period (3,0%, 2,4% 3,2%). No diferences were observed in the powerreduction index. There was a positive effect of active warm up over the 10 SRs, with a higher PMÁX, PMean and number of cycles after active warm up compared with rest (5,5% 2,2% e 2,8%) and without differences in the power reduction index. The active warm up led to increases in muscle temperature (TMUSC) (2,5°C), internal temperature TINT (0,1°C), heart rate (HR) and exhaustion perception, decreases in skin temperature (Tskin) and did not change the lactate concentration. This contributed for a better physical performance. The SRs also decreased Tskin and increased TMUSC, TINT, HR, exhaustion perception and lactate concentration. Although TMUSC and TINT values were higher in the evening period, the increase in these temperatures after active warm up were similar in both periods, showing that this protocol was able to evoke similar changes in TMUSC and TINT and improved physical performance in the 1st sprint. It was also able to keep the physical performance along the 10 SRs. This suggest that the active warm up induced an effect on muscle temperature that goes beyond to that obtained along the day through passive warm up.