Eight weeks of high-intensity interval training versus stretching do not change the psychoneuroendocrine response to a social stress test in emotionally impulsive humans.

PURPOSE: Research supports physical activity as a method to heighten stress resistance and resilience through positive metabolic alterations mostly affecting the neuroendocrine system. High-intensity interval training (HIIT) has been proposed as a highly effective time-saving method to induce those changes. However, existing literature relies heavily on cross-sectional analyses, with few randomised controlled trials highlighting the necessity for more exercise interventions. Thus, this study aims to investigate the effects of HIIT versus an active control group on the stress response to an acute psychosocial stressor in emotionally impulsive humans (suggested as being strong stress responders). METHODS: The study protocol was registered online (DRKS00016589) before data collection. Sedentary, emotionally impulsive adults (30.69 ± 8.20 y) were recruited for a supervised intervention of 8 weeks and randomly allocated to either a HIIT (n = 25) or a stretching group (n = 19, acting as active controls). Participants were submitted to a test battery, including saliva samples, questionnaires (self-efficacy- and perceived stress-related), visual analogue scales (physical exercise- and stress-related), and resting electroencephalography and electrocardiography assessing their reaction to an acute psychological stressor (Trier Social Stress Test) before and after the exercise intervention. RESULTS: HIIT increased aerobic fitness in all participants, whereas stretching did not. Participants from the HIIT group reported perceiving exercising more intensively than those from the active control group (ƞp2 = 0.108, p = 0.038). No further group differences were detected. Both interventions largely increased levels of joy post-TSST (ƞp2 = 0.209, p = 0.003) whilst decreasing tension (ƞp2 = 0.262, p < 0.001) and worries (ƞp2 = 0.113, p = 0.037). Finally, both interventions largely increased perceived levels of general self-efficacy (ƞp2 = 0.120, p = 0.029). CONCLUSION: This study suggests that 8 weeks of HIIT does not change the psychoneuroendocrine response to an acute psychological stress test compared to an active control group in emotionally impulsive humans. Further replications of supervised exercise studies highly powered with active and passive controls are warranted.

Effects of voluntary slow breathing on heart rate and heart rate variability: A systematic review and a meta-analysis.

Voluntary slow breathing (VSB) is used as a prevention technique to support physical and mental health, given it is suggested to influence the parasympathetic nervous system (PNS). However, to date, no comprehensive quantitative review exists to support or refute this claim. We address this through a systematic review and meta-analysis of the effects of VSB on heart rate variability (HRV). Specifically, we focus on HRV parameters indexing PNS activity regulating cardiac functioning, referred to as vagally-mediated (vm)HRV: (1) during the breathing session (i.e., DURING), (2) immediately after one training session (i.e., IM-AFTER1), as well as (3) after a multi-session intervention (i.e., AFTER-INT). From the 1842 selected abstracts, 223 studies were suitable for inclusion (172 DURING, 16 IM-AFTER1, and 49 AFTER-INT). Results indicate increases in vmHRV with VSB, DURING, IM-AFTER1, and AFTER-INT. Given the involvement of the PNS in a large range of health-related outcomes and conditions, VSB exercises could be advised as a low-tech and low-cost technique to use in prevention and adjunct treatment purposes, with few adverse effects expected.

The Influence of Relaxing and Self-Selected Stimulating Music on Vertical Jump Performance in Male Volleyball Players.

Most research concerning the effects of music on physical performance was conducted using endurance parameters. This study investigated the effects of relaxing (RLX) vs. self-selected stimulating music (SM) vs. no music (NM) on jump height (JH), jump power (PWR), and average rest period between jumps (RP) in 13 athletes (age: 25.5 ± 2.6 years). After a warm-up and listening to music (1 min) or NM, participants completed five squat jumps on a force plate. Psychological ratings of mood were assessed using a questionnaire before warm-up and after jumping. A one-way ANOVA was conducted to compare effects of music on JH, PWR, and RP. A Friedman test with Wilcoxon signed-rank test was used to detect changes in mood. There were no significant effects of music on JH (p = 0.162) and PWR (p = 0.162). A trend towards longer RP in RLX when compared to SM was detected (+2.72 s, +22%, p = 0.059, d = 0.35). Participants felt more "relaxed" (+3 ranks) and more "powerful" after listening to SM (+2 ranks). Following NM and RLX, athletes felt more "energetic" (each +3 ranks) but less energetic (-3 ranks) after SM. In conclusion, this study did not find any performance-enhancing effects of self-selected SM on jump performance. The influences of music on psychological ratings were inconclusive. For this reason, no evidence-based guidelines for the practical application of music in elite jumping athletes can be made, and more studies are warranted.