Passive heat therapy: a promising preventive measure for people at risk of adverse health outcomes during heat extremes.

The world is experiencing increased frequency, duration, and severity of life-threatening heat extremes. Most hospitalizations and excess deaths during extreme heat events are associated with preexisting diseases in older adults. As climate change persists, the global population ages and the number of individuals with chronic diseases expands, more people are at risk of adverse health outcomes during extreme heat events. Therefore, proactive preventive measures are urgently needed to mitigate heat-related health risks within these populations. In this context, passive heat therapy (e.g., hot baths, saunas, and water-perfused suits) emerges as a promising countermeasure to improve physiological resilience to a warming planet. Passive heating improves cardiovascular function and overall health in older adults and individuals living with chronic diseases, offering the prospect of reducing cardiovascular strain during hotter days. Moreover, some studies suggest that passive heat therapy can be an effective strategy for heat acclimation (i.e., improved thermoregulation). This review describes the existing literature on the effects of passive heat therapy on cardiovascular and thermoregulatory responses in individuals with higher heat-related health risks and explores the use of passive heating as a strategy for heat acclimation to mitigate health risks during extreme heat events.NEW & NOTEWORTHY Passive heat therapy improves cardiovascular function and health in middle-aged and older adults living with or without chronic diseases. In addition, preliminary studies indicate that passive heat interventions can induce heat acclimation, improving thermoregulatory responses. Thus, passive heat therapy could serve as a preventive measure for people at risk of adverse health outcomes during extreme heat events, improving resilience to ongoing climate change.

Dissimilar perceptual response between trained women and men in resistance training to concentric failure: A quasi-experimental study.

PURPOSE: This study compared sex-related affective responses during resistance training performed to concentric failure. METHODS: The study was a non-randomized trial (quasi-experimental study). Well-trained young participants were allocated into two groups according to sex (Women, n = 7, 21.1 ± 6.0 years, 57.6 ± 5.0 kg; and Men, n = 7, 28.3 ± 5.7 years, 88.3 ± 11.4 kg). Participants visited the laboratory three times: 1) 12-repetition maximum; 2-3) resistance training to concentric failure sessions. Perceptual measures were assessed before, during, and immediately after the resistance training sessions. The following were assessed: a) rating of perceived exertion for effort (RPE-E) and discomfort (RPE-D), b) feeling scale, c) physical activity affect scale (PAAS), d) felt arousal scale, and e) physical activity enjoyment scale (PACES). RESULTS: High levels of RPE-E and RPE-D were reported without between-groups differences (p > 0.218). Women reported a reduction in the feeling scale (p = 0.001) whereas men did not (p > 0.680). Larger effect sizes were observed for women compared to men in the felt arousal scale and PAAS (negative affect and fatigue). Feeling scale and felt arousal scale data plotted in a circumplex model of affect indicated a transition to high-activation and unpleasant-affect only for the women. There was good reliability between results from sessions 1 and 2. CONCLUSIONS: Training to concentric failure resulted in negative changes in affective perceptual responses only for women. This type of training should be used with caution since it may change the affect perception and reduce training adherence in women. Further studies are needed using larger sample sizes, different resistance-training exercises, and diverse training methods.

Effect of Photobiomodulation Therapy in the 1500 m Run: An Analysis of Performance and Individual Responsiveness.

Objective: The aims of this study were to verify the effects of photobiomodulation therapy (PBMT) on time trial run performance over 1500 m, as well as on individual responsiveness of recreative runners. Materials and methods: Nineteen recreationally trained runners participated in a randomized, crossover, double-blind placebo-controlled trial. The study was divided in four sessions: (1) incremental maximal running test; (2) 1500 m run control (without placebo or PBMT); and (3, 4) PBMT or placebo before 1500 m run. PBMT or placebo was applied over 14 sites per lower limb immediately before time trial run using a mixed wavelength device (33 diodes: 5 LASERs of 850 nm, 12 LEDs of 670 nm, 8 LEDs of 880 nm, and 8 LEDs with 950 nm). PBMT delivered 30 J per site, with a total energy dose of 840 J. Physiological variables [maximal oxygen uptake (VO2MAX), velocity associated to VO2MAX (vVO2MAX), peak of velocity, and respiratory compensation point (RCP)] were assessed during incremental maximal test. During 1500 m races we accessed the following: time, heart rate, and lower limb rate perception exertion per lap, total time, and blood lactate concentration ([Lac]). Results: PBMT had no significant difference and likely trivial effect for performance in the total time trial run over 1500 m compared to placebo. In the responsiveness analyses, 10 participants positively responded to PBMT, whereas total time reduced for responders (-10.6 sec; -3.18%) and increased for nonresponders (+6.0 sec; +1.73%). Responders presented higher aerobic parameters (VO2MAX and RCP) than nonresponders. Moreover, responders had lower time per lap and [Lac] (1 and 3 min) when PBMT was applied. Conclusions: PBMT applied immediately before running in noncontrolled environment was not able to improve the 1500 m performance of recreationally trained runners. However, responders to PBMT presented higher aerobic capacity than nonresponders.

Photobiomodulation Therapy Effects on Resistance Training Volume and Discomfort in Well-Trained Adults: A Randomized, Double-Blind, Placebo-Controlled Trial.

Objective: To investigate the effects of photobiomodulation therapy (PBMT) on resistance training volume and discomfort of well-trained adults. Background: PBMT has been used to attenuate fatigue in several physical exercise topics. However, it is unclear if PBMT can increase volume and reduce discomfort in resistance training well-trained individuals. Methods: Fourteen participants (women = 7, 27.7 ± 6.0 years and men = 7, 28.3 ± 5.7 years) visited the laboratory three times, 7 days apart. In the first visit, 12-repetition maximum (12-RM) test was performed unilaterally on the standing calf raise machine. In the second and third visits, subjects were randomly submitted to a PBMT (60 J per site, 6 sites per limb, total dose = 360 J) or placebo treatment on the gastrocnemius and soleus muscles with a randomized crossover design. Five minutes after the treatment, subjects began the resistance training session, performed unilaterally with six sets of repetitions to concentric failure. In addition, the rate of perceived exertion for discomfort (RPE-D) was asked after each set. Results: After the training session, it was observed a similar force reduction of 10.0 ± 13.6% for placebo and 7.7 ± 7.3% for PBMT (p = 0.815). No differences between PBMT and placebo was observed for the repetitions fatigue index (53.4 ± 11.7% and 50.0 ± 11.6%; p = 0.325) and total repetitions volume (55.4 ± 10.9 and 54.8 ± 13.0 reps; p = 0.764), respectively. RPE-D presented large means for all sets representing a large discomfort during resistance training to concentric failure for both PBMT (7.3 ± 2.3) and placebo (7.5 ± 2.5). Conclusions: The PBMT was not effective for increasing volume and reducing discomfort during resistance training performed to concentric failure by well-trained men and women.

Acute performance responses during repeated matches in combat sports: A systematic review.

OBJECTIVE: Investigate the acute effects of repeated combat sports matches on vertical jump and handgrip strength performance in grappling and striking modalities. DESIGN: Systematic review. METHODS: PubMed, Scopus, and Web of Science databases were searched. The following eligibility criteria for selecting studies were adopted: Population: Combat sports athletes; Intervention: Official or simulated matches; Comparator: Baseline versus after-matches performance; Outcome: Vertical jump and/or handgrip strength performance. PROSPERO: CRD42019129264 RESULTS: The systematic search resulted in 13 studies, including Brazilian jiu-jitsu, Greco-Roman, judo, taekwondo, and wrestling (freestyle and Greco-Roman) modalities, and a diverse number of repeated matches (i.e. 1-5). None of the studies adopted a randomized and controlled design and, consequently, none of them was classified as high quality. Brazilian jiu-jitsu and freestyle wrestling athletes presented an earlier onset of fatigue in upper and lower limbs, while judo and Greco Roman wrestling presented a later onset, from the third match. In taekwondo athletes, no fatigue was observed in the lower limbs, while handgrip strength decreased. However, studies have reported unclear data regarding the time-course of lower and upper limbs' fatigue following repeated matches in taekwondo. CONCLUSION: Both upper and lower limbs performance were affected after repeated matches in grappling combat sports when assessed by handgrip strength and vertical jump performance. In taekwondo, the studies have shown unclear results concerning the effects of repeated matches on upper and lower limb performance. There is a lack of studies classified as high-quality and investigations into the neuromuscular mechanisms underpinning fatigue after the repeated matches.