Effects of load intensity on exercise volume, muscle activity, blood lactate, circumference and muscle soreness during weight training to repetition failure in Republic of Korea: prospective study

Background: This study aimed to compare the effects of low-intensity (65% one-repetition maximum [1RM]) and high-intensity (85% 1RM) maximum repetition barbell curl exercises on exercise volume, blood lactate concentrations, upper arm circumference, and muscle soreness.Methods: Ten male participants with over six months of weight training experience performed barbell curls under both intensity conditions.Measurements were analyzed using two-way repeated measures ANOVA.Results: The low-intensity exercises resulted in a significantly greater total exercise volume compared to the high-intensity exercises, with a more pronounced decline in volume across sets.Muscle activation was higher under the high-intensity exercise conditions.Interestingly, blood lactate concentrations were elevated to a greater extent in the low-intensity exercises and remained elevated for a longer duration during the recovery period.Increases in upper arm circumference were observed only in the low-intensity exercises.Moreover, muscle soreness was significantly greater and more prolonged under the low-intensity exercise conditions compared to the high-intensity exercise conditions.Conclusion: In conclusion, low-intensity weight training induces more metabolic fatigue, swelling, and muscle soreness than high-intensity training, highlighting the need for sufficient recovery time between sessions.