Local Passive Warming Administered During the Transition Phase Impairs Subsequent Isokinetic Exercise Performance

PURPOSE: Performing a warm-up prior to a sports competition is essential for preventing injuries and maximizing subsequent perfor-mance. Passive warming has therefore received attention because it can effectively maintain an elevated muscle temperature (Tm) after a warm-up. The present study aimed to investigate the effects of local passive warming (LPW) administered during the transition phase between active warm-up and isokinetic exercises. METHODS: Eleven healthy men participated in this randomized crossover study. During the 30-minute transition period, a customized water-perfused warming pad was placed on the anterior thighs of the dominant legs (+3°C or +6°C based on the baseline skin temper-ature) or no intervention for the control group (CON). Subsequently, the total work, peak torque, and average power during isokinetic knee extensions (10 repetitions at a speed of 60°/sce) were measured. Using surface electromyography (EMG), the root mean square and mean frequency from the rectus femoris during knee extension were measured to assess neuromuscular activity. RESULTS: Total work (+6°C 1,289.8±389.3 vs. CON 1,437.3±408.2 Nm, p=.042), peak torque (+6°C 146.0±33.3 vs. CON 162.9±37.9 Nm, p=.022), and average power (+6°C 77.7±19.8 vs. CON 90.2±25.3 W, p=.012) were lower in the LPW +6°C group than in the CON group. EMG RMS was lower in the LPW +6°C group than in the CON group (+6°C 58.4±22.3 vs. CON 78.6±33.0 % MVC, p=.005). MF was higher in the LPW +6°C group than in the CON group (+6°C 87.5±12.4 vs. CON 81.4±11.0 Hz, p=.016). CONCLUSIONS: Local passive warming administered during the transition phase was not an appropriate strategy for boosting the performance of subsequent isokinetic exercises. Accordingly, the application of passive warming should be carefully chosen before exercise commences.