Physical activity is associated with cardiac autonomic function in adolescent men.

INTRODUCTION: Moderate to vigorous physical activity (MVPA) has been shown to be associated with autonomic regulation of the heart measured with heart rate variability (HRV). Only a limited amount of studies have examined this relationship among adolescents, and the effects of increasing PA on HRV is not well established. The aim of this study was to investigate how overall self-reported PA associates with HRV in a large population of adolescent men. METHODS: The study was part of the Finnish MOPO study consisting of 3629 young men (mean age 18, SD 1 years) enrolled for military call-ups in 2009-2013. Overall PA, including both the intensity and frequency of habitual exercise, was assessed by a questionnaire and the respondents categorized into four groups of PA (low, moderate, high and top). Short-term HRV, physical performance and body composition were measured. RESULTS: HRV, as indicated by mean ln rMSSD, increased according the PA categories as follows: low (3.65 ms (SD 0.7), p<0.001 vs. other groups), moderate (3.78 ms (0.6) p<0.001), high (3.85 ms (0.6) p<0.001) and top activity (3.93 ms (0.6) p<0.001) According to the multivariable linear regression analysis, a significant positive relationship (ß = 0.129, p<0.05) was observed between self-reported PA and ln rMSSD independent of body mass index, waist circumference and fat percentage. CONCLUSIONS: Physical activity was positively associated with cardiac autonomic regulation, in adolescent men. A linear increase in HRV according to PA was observed, suggesting that even slight increments in PA might be beneficial for cardiac autonomic regulation The results emphasize the importance of physical activity in improving cardiac health in young people.

Effects of far-infrared sauna bathing on recovery from strength and endurance training sessions in men.

PURPOSE: This study investigated effects of far-infrared sauna (FIRS) bathing on recovery from strength training and endurance training sessions, but also possible differences between FIRS and traditional (TRAD) Finnish sauna bathing. METHODS: Ten healthy physically active male volunteers had on various days either a 60 min hypertrophic strength training session (STS) or a 34-40 min maximal endurance training session (ETS), which was following by 30 min bathing in special FIRS sauna at temperature of 35-50°C and humidity of 25-35%. After the sauna, subjects sat for 30 min at room temperature (21°C and 25-30% humidity). In comparison, 30 min of TRAD took place at 35-50°C and in 60-70% humidity. Performance tests included maximal isometric bench press and leg press, counter movement jump (CMJ) and maximal oxygen uptake on a treadmill. RESULTS: After STS, there were decreases in maximal isometric bench press (p < 0.001), maximal isometric leg press (p < 0.001), CMJ (p < 0.001) and pH (p < 0.001), but increases in heart rate (p < 0.001) and lactate concentration (p < 0.001) as expected. During recovery there were no differences in any variables between FIRS and no sauna bathing (NO SAUNA). Maximal ETS increased oxygen uptake (p < 0.001), heart rate (p < 0.001), lactate concentration (p < 0.001) and decreased pH (p < 0.001) as expected. During recovery at 30 min, CMJ was significantly (p < 0.05) higher (0.34 ± 0.09 m) after FIRS bathing than after sitting with NO SAUNA (0.32 ± 0.0 m). After sauna heart rate was higher (p < 0.05) in TRAD (92 ± 13 beats/min) than in FIRS (71 ± 7 beats/min). CONCLUSION: In conclusion, deep penetration of infrared heat (approximately 3-4 cm into fat tissue and neuromuscular system) with mild temperature (35-50°C), and light humidity (25-35%) during FIRS bathing appears favorable for the neuromuscular system to recover from maximal endurance performance. FIRS bathing is a very light loading for the body and provides a comfortable and relaxing experience.