Effects of Pre- or Post-bath Resting in the Bathing After Workload on Changes in Blood Lactic Acid Levels / 日本温泉気候物理医学会雑誌

ABSTRACT

<b>Background</b> A 30-60 min rest after exercising is generally recommended before taking a bath. Although this was considered an appropriate bathing method, effects of pre-bath rest on recovery from exercise fatigue remain unclear. Here, we aimed to examine the effects on fatigue recovery of pre-bath rest after a workload, with the focus on changes in lactic acid levels. <BR><b>Methods and Results</b> Ten healthy adult men increased their blood lactic acid levels through a treadmill workload performed in accordance with the Bruce method, then took either a 60-min post-workload rest followed by a 10-min full-immersion 38°C bath (Experiment A) or a 10-min full-immersion 38°C bath followed by a 60-min rest (Experiment B). Body temperature, blood pressure, pulse rate, and blood lactic acid level were measured at three time points before workload (Test 1), after workload (Test 2), and after bathing/resting (Test 3). Decreases and percent decreases in blood lactic acid levels were calculated by comparing Test 3 results with Test 2 results. These calculated values and the measured values in three tests were compared between Experiment A and Experiment B using paired-t test. There were no significant differences in maximum systolic blood pressure, maximum diastolic blood pressure, maximum workload attained, and maximum pulse rate measurements between Experiment A and Experiment B. Differences in systolic blood pressure and diastolic blood pressure measurements in Tests 1, 2, and 3 were not significant. The pulse rates measured at the final measurement (Test 3) were significantly higher in Experiment A than in Experiment B (90.4 ± 18.2 bpm vs 79.6 ± 11.6 bpm, p = 0.04). No significant differences were observed in other measurement timings. The body temperature measurements at the final measurement were slightly higher in Experiment A than in Experiment B (36.4 ± 0.4 vs 36.1 ± 0.3°C, p = 0.05). No significant differences were observed in other measurements. Blood lactic acid levels before workload (Test 1) were significantly higher in Experiment A (6.6 ± 4.7mmol/L) than in Experiment B (2.0 ± 1.4 mmol/L, p = 0.02), but those at other measurement points (Test 2 and Test 3) were similar. Neither decreases nor percentage decreases in blood lactic acid levels differed between Experiment A and Experiment B.<BR><b>Conclusions</b> Resting before a post-exercise bath did not change the decreases or percent decreases in blood lactic acid levels after bathing at 38°C, suggesting negligible effects of pre-bath resting on recovery from exercise fatigue.