Consensus recommendations on training and competing in the heat

Abstract

Exercising in the heat induces thermoregulatory and other physiological strain that can lead to impairments in endurance exercise capacity. The purpose of this consensus statement is to provide up-to-date recommendations to optimize performance during sporting activities undertaken in hot ambient conditions. The most important intervention one can adopt to reduce physiological strain and optimize performance is to heat acclimatize. Heat acclimatization should comprise repeated exercise-heat exposures over 1-2 weeks. In addition, athletes should initiate competition and training in a euhydrated state and minimize dehydration during exercise. Following the development of commercial cooling systems (e.g., cooling vest), athletes can implement cooling strategies to facilitate heat loss or increase heat storage capacity before training or competing in the heat. Moreover, event organizers should plan for large shaded areas, along with cooling and rehydration facilities, and schedule events in accordance with minimizing the health risks of athletes, especially in mass participation events and during the first hot days of the year. Following the recent examples of the 2008 Olympics and the 2014 FIFA World Cup, sport governing bodies should consider allowing additional (or longer) recovery periods between and during events for hydration and body cooling opportunities when competitions are held in the heat.

The effects of single versus twice daily short term heat acclimation on heat strain and 3000m running performance in hot, humid conditions

“…This method also increases aldosterone, a fluid-regulatory hormone which effects sodium and urine water retention, therefore, facilitating fluid-regulatory efficiency and mediating hypervolemia (Garrett, et al, 2009). In this study no practical or statistical significant improvements in sweat rate occurred, suggesting no heat dissipation improvements, as sudomotor function adaptation typically occurs in the latter stages of HA (Armstrong and Maresh, 1991;Racinais et al, 2015).…”

“…Although, contrary to less work completed during controlled hyperthermia methods, fixed exercise intensity may be optimal for larger cohorts of military personnel, due to lower exercise intensity and simplified administration . Moreover, although guidelines suggest >60 min exposure time for HA (Taylor, 2014;Racinais et al, 2015), in line with the nature of this ' aim of prompt STHA, 45 min sessions may be more attractive to the busy, modern-day athlete or called upon military soldier, especially if they are adopted twice daily. Future studies must investigate the method prescribed to achieve the target level of physiological strain by increasing T re to a fixed absolute temperature, or change from baseline, which may be performed prior to the exposure within a hot bath or the selected exercise intensity may have to be more rigorous, as a means of thermal stimuli.…”

“…Reductions in self-paced exercise or fixed intensity military tasks, are a result of physiological strain and, or behavioural thermoregulation during heat stress (Sawka et al, 2011;Racinais et al, 2015). To compete or serve optimally under heat stress, heat acclimation or acclimatization is typically recommended (Racinais et al, 2015), as repeated heat strain confer physiological and metabolic adaptations, in addition to reducing perceptual feelings, which alleviate physiological strain and enhance physical performance (Sawka et al, 2011;Taylor, 2014;Racinais et al, 2015). To induce such adaptations, repeated daily exercise is performed in hot environmental conditions, which may be simulated (i.e.…”

Short-term, low-volume training improves heat acclimatization in an operational context

“…Indeed, passive heat acclimatization is less efficient than active heat acclimatization by work-induced physical activity (Horvath and Shelley, 1946;Hellon et al, 1956;Joy et al, 1964;Pandolf et al, 1977) or training sessions (Périard et al, 2015(Périard et al, , 2016Racinais et al, 2015;Tyler et al, 2016). To be effective, in terms of heat acclimation-induced physiological modifications, an exercise session performed in the heat should trigger high sweat rates and largely increase core body temperature (Henane et al, 1977;Racinais et al, 2015). This could be achieved with any session modalities in duration or intensity (Houmard et al, 1990;Gibson et al, 2015), although it is suggested that high-intensity exercise may be more efficient than lower-intensity exercise (Houmard et al, 1990).…”

“…We chose a short period (5 days) because soldiers or personnel in this context were not available for a longer time and were engaged in their tasks by the end of the first week. This period is also sufficient to induce partial or complete modification of several physiological factors (decreased HR and core temperature at rest and during exercise, increased plasma volume) and improve thermal discomfort (Périard et al, 2015;Racinais et al, 2015).…”