PurposeWe evaluated the effect of different water immersion (WI) temperatures on post-exercise cardiac parasympathetic reactivation.MethodsEight young, physically active men participated in four experimental conditions composed of resting (REST), exercise session (resistance and endurance exercises), post-exercise recovery strategies, including 15 min of WI at 15°C (CWI), 28°C (TWI), 38°C (HWI) or control (CTRL, seated at room temperature), followed by passive resting. The following indices were assessed before and during WI, 30 min post-WI and 4 hours post-exercise: mean R-R (mR-R), the natural logarithm (ln) of the square root of the mean of the sum of the squares of differences between adjacent normal R–R (ln rMSSD) and the ln of instantaneous beat-to-beat variability (ln SD1).ResultsThe results showed that during WI mRR was reduced for CTRL, TWI and HWI versus REST, and ln rMSSD and ln SD1 were reduced for TWI and HWI versus REST. During post-WI, mRR, ln rMSSD and ln SD1 were reduced for HWI versus REST, and mRR values for CWI were higher versus CTRL. Four hours post exercise, mRR was reduced for HWI versus REST, although no difference was observed among conditions.ConclusionsWe conclude that CWI accelerates, while HWI blunts post-exercise parasympathetic reactivation, but these recovery strategies are short-lasting and not evident 4 hours after the exercise session.

The effect of an adventure sprint race (ASR) on T-cell proliferation, leukocyte count and muscle damage was evaluated. Seven young male runners completed an ASR in the region of Serra do Espinhaço, Brazil. The race induced a strong leukocytosis (6.22±2.04×103 cells/mm3 before vs 14.81±3.53×103 cells/mm3 after the race), marked by a significant increase of neutrophils and monocytes (P<0.05), but not total lymphocytes, CD3+CD4+ or CD3+CD8+ cells. However, the T-cell proliferative response to mitogenic stimulation was increased (P=0.025) after the race, which contradicted our hypothesis that ASR, as a high-demand competition, would inhibit T-cell proliferation. A positive correlation (P=0.03, r=0.79) was observed between the proliferative response of lymphocytes after the race and the time to complete the race, suggesting that the proliferative response was dependent on exercise intensity. Muscle damage was evident after the race by increased serum levels of aspartate amino transferase (24.99±8.30 vs 50.61±15.76 U/L, P=0.003). The results suggest that humoral factors and substances released by damaged muscle may be responsible for lymphocyte activation, which may be involved in muscle recovery and repair.

Various post-exercise strategies have been proposed to accelerate recovery during periods of training. However, the effects of water immersion (WI) temperature on recovery amid multiple daily exercise bouts are not well investigated. PURPOSE: To evaluate the effects of cold and warm water immersion temperatures between acute exercise bouts vs. no WI recovery on running performance. METHODS: Nine recreationally trained men (age: 24.0 ± 6.0 years old) participated in four experimental sessions using a crossover design. Each experimental session consisted of unilateral eccentric knee flexion exercise and 90 min of treadmill running at 70% of peak oxygen consumption followed by 15 min of WI at 15°C, 28°C or 38°C or passive recovery seated at room temperature (CON). Four hours following WI or CON, subjects completed a 5 km running time trial. Rectal temperature (Trec), heart rate, and excess post-exercise oxygen consumption (EPOC) were measured. RESULTS: Statistical analyses indicated that time trial performance was not affected by post-exercise recovery by WI (P > .05). The magnitude-based inferences indicated that 15°C (+ 3.6 ± 7.8%) likely and 28°C (+ 3.2 ± 7.5%) possibly improved recovery compared with CON, while the effect of 38°C (-0.1 ± 12.3%) on recovery was unclear. During WI, heart rate and rectal temperature were not different from CON, but EPOC was higher in 15°C and 28°C compared to CON. Trec in 15°C was lower than CON from the 15th min post WI. EPOC was also greater in 15°C post WI compared to CON. CONCLUSION: WI at 15°C and 28°C following acute exercise likely and possibly, respectively, improved subsequent 5 km running time trial performance. We speculate that the faster recovery in core temperature post-exercise may underlie these improvements in recovery.

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