Abstract
OBJECTIVE: This study aimed to determine the association between changes in lactate production and levels of physical activity in a group of healthy young adults in response to two squat training protocols. MATERIAL AND METHODS: Twenty-nine students majoring in Sports Science willingly participated in this study. Participants visited the lab four times within a two-week period, ensuring at least 48 h between visits. In each session, they completed three sets of 12 repetitions at 75% 1RM and three sets of 30 repetitions at 50% of maximum strength, with the order of protocols being randomized. RESULTS: In the regression analysis, there was a significant positive association between lactate delta changes immediately post-squat at 50% of maximum strength at session 2 with the variable "sex: women" (β: 3.02, 95% CI [-0.18-0.30], p = 0.047) and BMI (kg/m(2)). Age exhibited a positive association (β: 0.19, 95% CI [0.02-0.36], p = 0.032) with lactate delta changes immediately post-squat at 75% of maximum strength at session 2. There was also a significant inverse association between lactate delta changes at 10 min post-squat test exercise at 75% of maximum strength at session 1 and 2, and vigorous physical activity (-0.01, 95% CI [-0.02-0.00], p = 0.046). CONCLUSION: In summary, this study provides valuable insights into the association between lactate production and physical activity levels in young, healthy adults undergoing different squat training protocols. These findings suggest that intense physical activity may be associated with lower lactate production, indicating greater metabolic efficiency. In addition, sex differences in metabolic responses were observed, emphasizing the importance of personalized approaches in program design.