The effects of lower body passive heating combined with mixed-method cooling during half-time on second-half intermittent sprint performance in the heat

Cold water immersion of the hand and forearm during half-time improves intermittent exercise performance in the heat

The present study aimed to investigate the effect of cold water immersion of the hand and forearm during half-time (HT) on intermittent exercise performance and thermoregulation by imitating intermittent athletic games in the heat. In a randomized crossover design, 11 physically active men performed the first half (first and second block) and second half (third and fourth block) intermittent cycling exercise protocol, which consisted of a 5-s maximal power pedalling (body weight × 0.075 kp) every minute separated by 25-s of unloaded pedalling and rest (30 s) in the heat (33°C, 50% relative humidity). The two-halves were separated by a 15-min HT. During HT, the participants were assigned to the CON (sedentary resting) or COOL (immersion of hands and forearms in cold water at 15-17°C) condition. The mean power output in the second half was significantly greater (third and fourth block: p < 0.05) in the COOL than in the CON condition. Moreover, there was a significant decrease in the rectal (0.54 ± 0.17°C, p < 0.001) and mean skin (1.86 ± 0.34°C, p < 0.05) temperatures of the COOL condition during HT. Furthermore, the heart rate (16 ± 7 bpm, p < 0.05) and skin blood flow (40.2 ± 10.5%, p < 0.001) decreased at the end of HT in the COOL condition. In the second half, thermal sensation was more comfortable in the COOL condition (p < 0.001). Cold water immersion of the hand and forearm during HT improved physiological and reduced perceived heat stress. Moreover, it prevented a reduction in intermittent exercise performance in the second half.

Effects of Postexercise Sauna Bathing on Recovery of Swim Performance

PURPOSE

Despite indications of positive effects of sauna (SAU) interventions, effects on performance recovery are unknown. The aim of the current study was to investigate acute effects of SAU bathing after an intensive training session on recovery of swim performance.

METHODS

In total, 20 competitive swimmers and triathletes (3 female and 17 male) with a minimum of 2 y of competition experience (national level or higher) participated in the study. Athletes completed an intensive training session followed by either a SAU bathing intervention or a placebo (PLAC) condition in a randomized order. SAU consisted of 3 × 8 min of SAU bathing at 80-85°C, whereas during PLAC, athletes applied a deidentified, pH-balanced massage oil while passively resting in a seated position. Prior to training, swimmers conducted a 4 × 50-m all-out swim test that was repeated on the following morning. Furthermore, subjective ratings of fatigue and recovery were measured.

RESULTS

Swimmers performed significantly worse after SAU (4 × 50-m pre-post difference: +1.69 s) than after PLAC (-0.66 s; P = .02), with the most pronounced decrease in the first 50 m (P = .04; +2.7%). Overall performance of 15 athletes deteriorated (+2.6 s). The subjective feeling of stress was significantly higher after SAU than after PLAC (P = .03).

CONCLUSION

Based on published findings, the smallest substantial change in swimming performance is an increase in time of more than 1.2 s; thus, the observed reductions appear relevant for competitive swimmers. According to the current results, coaches and athletes should be careful with postexercise SAU if high-intensity training and/or competitions are scheduled on the following day.

Impact of Ice Slurry Ingestion During Break-Times on Repeated-Sprint Exercise in the Heat

The study aimed to investigate the effects of ice slurry ingestion during break times and half-time (HT) on repeated-sprint performance and core temperature in the heat. Seven males performed two different trials as follows: ice slurry (-1°C) or room temperature water ingestion at each break and HT break at 36.5°C, 50% relative humidity. Participants performed 30 sets of 1-min periods of repeated- sprint exercises protocol using a cycling ergometer. Each period consisted of 5 sec of maximal pedaling, 25 sec of pedaling with no workload, and 30 sec of rest; two sets of exercise periods were separated by 10 min of rest. Each break was implemented for 1 min after every 5 sets. The rectal temperature in ice slurry ingestion was significantly lower than that of the room temperature water at 45 set (p=0.04). Total and mean work done was greater in ice slurry ingestion compared to room temperature water ingestion (p < 0.05). These results suggested that ice slurry ingestion during break times and HT break may be an effective cooling strategy to attenuate the rise of core temperature in the second half of exercise and improve the repeated-sprint exercise capacity in the heat.

Translating Science Into Practice: The Perspective of the Doha 2019 IAAF World Championships in the Heat

Hot and humid ambient conditions may play a major role during the endurance events of the 2019 IAAF world championships, the 2020 summer Olympics and many other sports events. Here, various countermeasures with scientific evidence are put in perspective of their practical application. This manuscript is not a comprehensive review, but rather a set of applied recommendations built upon sound scientific reasoning and experience with elite athletes. The primary recommendation for an athlete who will be competing in the heat, will be to train in the heat. This acclimatization phase should last for 2 weeks and be programmed to accommodate the taper and travel requirements. Despite extensive laboratory-based research, hydration strategies within athletics are generally dictated by the race characteristics. The main opportunities for hydration are during the preparation and recovery phases. In competition, depending on thirst, feeling, and energy requirements, water may be ingested or poured. The athletes should also adapt their warm-up routines to the environmental conditions, as it may do more harm than good. Avoiding harm includes limiting unnecessary heat exposure before the event, warming-up with cooling aids such as ice-vest or cold/iced drinks, and avoiding clothing or accessories limiting sweat evaporation. From a medical perspective, exertional heat stroke should be considered immediately when an athlete collapses or struggles during exercise in the heat with central nervous system disorders. Once a rectal temperature >40.5°C is confirmed, cooling (via cold water immersion) should be undertaken as soon as possible (cool first/transport second).