Core body temperature responses during competitive sporting events: A narrative review

Far from Home: Heat-Illness Prevention and Treatment in Austere Environments

Austere environments present unique challenges concerning the prevention and treatment of exertional heat-illness patients that may greatly increase the risks of morbidity and mortality. For athletes, occupational groups, and others who may work, train, or compete in austere environments, proper preparation and planning may be lifesaving. The roles of acclimatization and hydration are often emphasized in the literature, but other important risk factors may be overlooked. Work capacity, especially aerobic work capacity, will always be reduced in hot environments, and individuals should understand that simply slowing down, to reduce metabolic heat production, can be considered the universal precaution to mitigate heat stress and strain. Conversely, appropriate rehydration alone does not mitigate other risk factors, such as metabolic heat production, high ambient temperature, or inadequate physical fitness. Risk factor-specific mitigation recommendations are provided, and areas where additional research is needed are identified. The ability to recognize the signs and symptoms of heat illness early in the progression of illness is especially important in austere environments due to the possibility of delayed access to higher levels of medical care. Treatment considerations in austere environments include knowledge of availability and effectiveness of cooling modalities such as natural bodies of water. Medications such as antipyretics, dantrolene, and nonsteroidal anti-inflammatory drugs are not recommended to treat a suspected heat casualty. Aggressive cooling, with the objective of reducing core temperature to <39°C within 30-min, is the treatment priority.

Thermal and Biomechanical Responses of Amateur, Elite and World Cup Athletes During a World Cup Sprint Triathlon in the Heat

OBJECTIVES

Core temperature (TCORE), skin temperature (TTORSO) and running kinematics were measured across different athlete categories at a World Cup Sprint Triathlon, occurring during a heatwave (~ 25-31 °C Wet Bulb Globe Temperature [WBGT]).

METHODS

Sixty-six triathletes participated: 21 World Cup (7 females), 32 Hong Kong-Elite (HK-Elite; 8 females) and 13 Amateur (6 females).

RESULTS

Seventeen triathletes displayed a TCORE > 40.0 °C and two > 41.0 °C. Peak TCORE was not different between athlete categories (World Cup: 39.7 ± 0.6 °C; HK-Elite: 39.9 ± 0.8 °C; Amateur: 39.5 ± 0.8 °C; p = 0.357). However, there was an interaction between race phase and category (p = 0.001). Changes in TCORE for World Cup (2.4 ± 0.4 °C) and HK-Elite (2.5 ± 1.0 °C) were greater than for Amateurs (1.5 ± 0.7 °C). Peak TTORSO was higher in HK-Elites during afternoon races compared with morning World Cup races (p < 0.001). TTORSO reduced during the swim (pbonf < 0.001), then increased during the bike (pbonf < 0.001) but not run (pbonf = 1.00). World Cup athletes (3.15 ± 0.23 m) displayed longer strides (HK-Elites: 2.64 ± 0.35 m; Amateurs: 2.18 ± 0.30 m; pbonf < 0.001), shorter contact times (209.3 ± 13.7 ms; HK-Elites: 237.8 ± 23.0 ms; Amateurs: 262.9 ± 31.0 ms, pbonf < 0.001) and higher stride frequency (182.9 ± 6.3 strides.min-1) than HK-Elites (173.9 ± 6.8 strides.min-1) and Amateurs (173.2 ± 8.7 strides.min-1, pbonf < 0.001), which were comparable. There were no biomechanical changes over time and no interactions.

CONCLUSION

Different athlete categories displayed comparable peak TCORE responses. Amateur triathletes tolerated TCORE > 40.0 °C without heat illness symptoms. TCORE may rise > 41 °C during a sprint triathlon held under Blue flag conditions (~ 26 °C WBGT), questioning the suitability of sprint-distance triathlons as a safer alternative to Olympic-distance triathlons under Red/Black flag conditions (> 30.1 °C WBGT).

Hyperthermia and Exertional Heatstroke During Running, Cycling, Open Water Swimming, and Triathlon Events

Few previous epidemiological studies, sports medicine position statements, and expert panel consensus reports have evaluated the similarities and differences of hyperthermia and exertional heatstroke (EHS) during endurance running, cycling, open water swimming, and triathlon competitions. Accordingly, we conducted manual online searches of the PubMed and Google Scholar databases using pre-defined inclusion criteria. The initial manual screenings of 1192 article titles and abstracts, and subsequent reviews of full-length pdf versions identified 80 articles that were acceptable for inclusion. These articles indicated that event medical teams recognized hyperthermia and EHS in the majority of running and triathlon field studies (range, 58.8 to 85.7%), whereas few reports of hyperthermia and EHS appeared in cycling and open water swimming field studies (range, 0 to 20%). Sports medicine position statements and consensus reports also exhibited these event-specific differences. Thus, we proposed mechanisms that involved physiological effector responses (sweating, increased skin blood flow) and biophysical heat transfer to the environment (evaporation, convection, radiation, and conduction). We anticipate that the above information will help race directors to distribute pre-race safety advice to athletes and will assist medical directors to better allocate medical resources (eg, staff number and skill sets, medical equipment) and optimize the management of hyperthermia and EHS.

The Physiological Requirements of and Nutritional Recommendations for Equestrian Riders

Equestrian sport is under-researched within the sport science literature, creating a possible knowledge vacuum for athletes and support personnel wishing to train and perform in an evidence-based manner. This review aims to synthesise available evidence from equitation, sport, and veterinary sciences to describe the pertinent rider physiology of equestrian disciplines. Estimates of energy expenditure and the contribution of underpinning energy systems to equestrian performance are used to provide nutrition and hydration recommendations for competition and training in equestrian disciplines. Relative energy deficiency and disordered eating are also considered. The practical challenges of the equestrian environment, including competitive, personal, and professional factors, injury and concussion, and female participation, are discussed to better highlight novelty within equestrian disciplines compared to more commonly studied sports. The evidence and recommendations are supported by example scenarios, and future research directions are outlined.