Autores
Bartolome, Ignacio , Garcia, Angel , SIQUIER COLL, JESÚS, Gil, Maria Concepcion Robles , Grijota, Francisco J. , Maynar-Marino, Marcos
Abstract
Introduction: Nowadays, there is evidence regarding a beneficial effect of heat on neuromuscular strength and muscle hypertrophy development. The aim of this study is to evaluate the effects of a 4-week passive sauna bathing program to extreme heat (100 +/- 2 degrees C) as a support for a resistance strength training program on maximal strength and body composition. Methods: 30 young male subjects participated in the study. They were randomly assigned to a Hyperthermia group (HG, n = 14; age: 20.48 (19.12-22-30) years; weight: 76.30 (71.00-79.00) Kg; BMI: 23.92 (22.93-24.87) Kg/m(2)), or to a Normothermia group (NG, n = 15; age: 19.95 (19.10-21-94) years; weight: 61.70 (59.45-72.90) Kg; BMI: 21.56 (20.42-23.26) Kg/m(2)). All participants followed the same lower limb strength training program (2 exercises; 4 sets of 10 repetitions at 75% 1RM with progressive loading). Additionally, HG underwent two weekly sessions of exposure to extreme heat in a sauna (100 +/- 2 degrees C and 24 +/- 1% relative humidity, four sets of 10 min, 2 days per week). The intervention lasted for 4 weeks, followed by a 4-week deconditioning period. Maximum isometric knee flexion-extension strength, maximum counter-resistance strength, as well as body composition and anthropometric variables were assessed. Results: The HG group significantly increased body weight (p < 0.05) and muscle mass (p < 0.05), while their sum of six skinfolds (Sigma 6 skinfolds) significantly decreased (p < 0.05). Both groups improved their 1RM squat performance following the intervention program (p < 0.05; HG: r = 0.86; NG: r = 0.89). However, only the HG group continued to improve their squat 1RM after the deconditioning period (p < 0.001; r = 0.93), as well as their leg press 1RM (p < 0.01; r = 0.94). Maximal isometric strength increased only in the NG group at the end of the training program, with a significant increase in knee flexion torque (p < 0.05; r = 0.76). In contrast, the HG group showed significant increases in isometric strength after the deconditioning period in both knee extension (p < 0.05; r = 0.76) and knee flexion (p < 0.05; r = 0.75). Conclusions: A four-week period of passive sauna bathing at extreme heat appears to alter the chronology of strength responses. It also seems to induce favorable responses in terms of strength development and body composition.
