Tracking Of Blood Lactate Response Across Eight Sessions Of Muscular Endurance Resistance Training

Abstract

Muscular endurance resistance training (MERT) has been shown to improve the onset of blood lactate accumulation (OBLA). It has been speculated that improvements in OBLA following MERT is related to metabolic adaptations associated with continued exposure to increased blood lactate concentrations. PURPOSE: The purpose of this study was to investigate metabolic responses during each training session of a 4 week MERT program in aerobically trained males. METHODS: 17 males, ages 18-45, participated in this study. Subjects were randomly assigned to either an experimental (EX) or control (CON) group, 9 EX and 8 CON. Baseline measures included VO2max and OBLA using a cycle ergometer, and 1 repetition maximum (1RM) for: leg press (LP), leg curl (LC), and leg extension (LE). The EX group performed MERT (4 sets of 12-15 repetitions at 50% of 1RM for LP, LC, and LE) for 4 weeks with 2 sessions per week. Resistance was increased after 4 sessions to accommodate any potential strength gains. Pre and post blood lactate concentrations were measured for each MERT session. Both groups were instructed to maintain current aerobic training throughout the study with participants returning to the lab to repeat all baseline measures. T-tests were used to determine if significant between group differences existed using delta scores (post-pre). RESULTS: No significant differences in baseline measurements were observed (p>0.05). No significant group differences were observed for VO2max, OBLA, LP, and LE. However, significant group differences were observed for LC (kg) (EX 9.21±5.35 vs. CON: -0.142±5.08). The average blood lactate response (mmol/L) for the first 4 MERT sessions ranged from 7.0±0.716 to 13.8±1.76 and the last 4 sessions ranged 8.23±0.956 to 13.8±0.763. CONCLUSIONS: 4 weeks of MERT did not significantly improve VO2max, OBLA, LP, and LE but did improve LC. Although subjects performed all MERT at the same percentage of 1RM a large range of lactate responses were observed between subjects. The range in lactate responses suggests that the relative intensity of the exercise and metabolic responses were not the same between subjects. It may be more appropriate to assign training load with MERT based on lactate response to ensure similar metabolic responses between subjects.