Investigation of the effects of rapid weight loss on strength and muscle activation

The purpose of this study is to investigate the effects of at least 5% body weight loss in 48 hours on strength and muscle activation. Twelve elite male combat sports athletes who previously had experience weight loss for competition participated voluntarily this study. Participants took part in both control and experimental treatment according to the random cross-over design with a one-week interval. Performance and muscle activation measurements performed before rapid weight loss (BRWL), after rapid weight loss (ARWL), recovery-1 (R1), recovery-2 (R2) and recovery-3 (R3). Hand grip strength, vertical jump height, anaerobic power and muscular endurance measurements were performed as performance measurements. Muscle activations were measured in vastus medialis (VM), vastus lateralis (VL) and rectus femoris (RF) muscles during vertical jump and muscular endurance measurements. Two-way analysis of variance (ANOVA) with repeated measures were used to normally distributed data for statistical analysis. Friedman and Wilcoxon tests were used to non-normally distributed data. According to statistical analyses results there were no significant differences in hand grips strength and vertical jump heights (p>0,05). There is a significant decrease in peak anaerobic power between BRWL and ARWL measurements (p<0,05). However, this negative effect disappeared during the recovery period (p>0,05). Muscular endurance performance was negatively affected by rapid weight loss and this effect continued throughout the entire recovery period (p<0,05). There is no significant difference in muscle activation after rapid weight loss (p>0,05). As a result, the rapid weight loss of %5,6 in 48 hours has been found to have negative effects on anaerobic peak power and muscular endurance performance. Key Words: Combat sports, rapid weight loss, dehydration, anaerobic power, muscular endurance, electromyography