Hot water immersion: Maintaining core body temperature above 38.5°C mitigates muscle fatigue.

PURPOSE: Hot water immersion (HWI) has gained popularity to promote muscle recovery, despite limited data on the optimal heat dose. The purpose of this study was to compare the responses of two exogenous heat strains on core body temperature, hemodynamic adjustments, and key functional markers of muscle recovery following exercise-induced muscle damage (EIMD). METHODS: Twenty-eight physically active males completed an individually tailored EIMD protocol immediately followed by one of the following recovery interventions: HWI (40°C, HWI40 ), HWI (41°C, HWI41 ) or warm water immersion (36°C, CON36 ). Gastrointestinal temperature (Tgi ), hemodynamic adjustments (cardiac output [CO], mean arterial pressure [MAP], and systemic vascular resistance [SVR]), pre-frontal cortex deoxyhemoglobin (HHb), ECG-derived respiratory frequency, and subjective perceptual measures were tracked throughout immersion. In addition, functional markers of muscle fatigue (maximal concentric peak torque [Tpeak ]) and muscle damage (late-phase rate of force development [RFD100-200 ]) were measured prior to EIMD (pre-), 24 h (post-24 h), and 48 h (post-48 h) post-EIMD. RESULTS: By the end of immersion, HWI41 led to significantly higher Tgi values than HWI40 (38.8 ± 0.1 vs. 38.0°C ± 0.6°C, p < 0.001). While MAP was well maintained throughout immersion, only HWI41 led to increased (HHb) (+4.2 ± 1.47 µM; p = 0.005) and respiratory frequency (+4.0 ± 1.21 breath.min-1 ; p = 0.032). Only HWI41 mitigated the decline in RFD100-200 at post-24 h (-7.1 ± 31.8%; p = 0.63) and Tpeak at post-48 h (-3.1 ± 4.3%, p = 1). CONCLUSION: In physically active males, maintaining a core body temperature of ~25 min within the range of 38.5°C-39°C has been found to be effective in improving muscle recovery, while minimizing the risk of excessive physiological heat strain.

Are there bilateral isokinetic shoulder rotator differences in basketball male players?

BACKGROUND: The internal (IR) and external (ER) rotator shoulder strength are often assess in the upper limb sports to prevent a risk of injuries. The purpose of this comparative study was to measure the agonist/antagonist balance of shoulder strength and to determine whether significant differences exist between the dominant and nondominant sides in basketball players compared to a control groups. METHODS: During the championship, 23 elite male-basketball players (BB) and 23 healthy males (CG) were tested bilaterally on a Cybex Norm isokinetic dynamometer in a seated position with 45° shoulder abduction in the scapular plane at 60°.s-1 and 180°.s-1 in concentric (CON) and 60°.s-1 in eccentric (ECC) modes. RESULTS: No significant differences were found for normalized values to body weight (N.m/kg-1) between the both groups and ER/IR, ECC/CON and functional deceleration ratios were similar. BB have a bilateral difference with higher ER of the dominant side comparatively to the opposite (P<0.05). CONCLUSIONS: Unlike other sports that increase the performance of IR dominant side, the basketball player isokinetic profile could indicate a strengthening in the external rotators of the dominant side. This bilateral difference could be explained by the repetition of the specific movements in the ball control but this was not large enough for the ER/IR ratios to be significantly different with CG. The ratios analysis does not report an imbalance associated with a high risk of shoulder injuries.