Effect of Individual Environmental Heat-Stress Variables on Training and Recovery in Professional Team Sport

Abstract

<jats:p><jats:italic><jats:bold>Context</jats:bold>:</jats:italic> Exercise in hot environments increases body temperature and thermoregulatory strain. However, little is known regarding the magnitude of effect that ambient temperature (<jats:italic>T<jats:sub>a</jats:sub></jats:italic>), relative humidity (RH), and solar radiation individually have on team-sport athletes. <jats:bold><jats:italic>Purpose</jats:italic></jats:bold><jats:italic>:</jats:italic> To determine the effect of these individual heat-stress variables on team-sport training performance and recovery. <jats:italic><jats:bold>Methods</jats:bold>:</jats:italic> Professional Australian Rules Football players (N = 45) undertook 8-wk preseason training producing a total of 579 outdoor field-based observations with <jats:italic>T<jats:sub>a</jats:sub></jats:italic>, RH, and solar radiation recorded at every training session. External load (distance covered, in m/min; percentage high-speed running [%HSR] &gt;14.4 km/h) was collected via a global positioning system. Internal load (ratings of perceived exertion and heart rate) and recovery (subjective ratings of well-being and heart-rate variability [root mean square of the successive differences]) were monitored throughout the training period. Mixed-effects linear models analyzed relationships between variables using standardized regression coefficients. <jats:italic><jats:bold>Results</jats:bold>:</jats:italic> Increased solar-radiation exposure was associated with reduced distance covered (−19.7 m/min, <jats:italic>P</jats:italic> &lt; .001), %HSR (−10%, <jats:italic>P</jats:italic> &lt; .001) during training and rMSSD 48 h posttraining (−16.9 ms, <jats:italic>P</jats:italic> = .019). Greater RH was associated with decreased %HSR (−3.4%, <jats:italic>P</jats:italic> = .010) but increased percentage duration &gt;85% HR<jats:sub>max</jats:sub> (3.9%, <jats:italic>P</jats:italic> &lt; .001), ratings of perceived exertion (1.8 AU, <jats:italic>P</jats:italic> &lt; .001), and self-reported stress 24 h posttraining (−0.11 AU, <jats:italic>P</jats:italic> = .002). In contrast, higher <jats:italic>T<jats:sub>a</jats:sub></jats:italic> was associated with increased distance covered (19.7 m/min, <jats:italic>P</jats:italic> &lt; .001) and %HSR (3.5%, <jats:italic>P</jats:italic> = .005). <jats:italic><jats:bold>Conclusions</jats:bold>:</jats:italic> The authors show the importance of considering the individual factors contributing to thermal load in isolation for team-sport athletes and that solar radiation and RH reduce work capacity during team-sport training and have the potential to slow recovery between sessions.</jats:p>

Recovery with a fan-cooling jacket after exposure to high solar radiation during exercise in hot outdoor environments

“…In the WBGT index equation, wet-bulb temperature, dry-bulb temperature, and black-globe temperature account for 70%, 10%, and 20% of the heat stress, respectively ( 1 ). Despite field training and major sporting competitions (e.g., Tokyo 2020, FIFA World Cup Qatar 2022) being conducted in hot outdoor environments (in the presence of solar radiation) ( 2 , 3 ), the vast majority of scientific studies are conducted in indoor environments ( 4 ), without the presence of solar radiation.…”

Increased carbohydrate availability effects energy and nutrient periodisation of professional male athletes from the Australian Football League

“…However, previous studies have repeatedly shown that elite athletes often fail to achieve an EI that is equivalent to their EE (Hill and Davies, 2002, Fudge et al, 2006, Bescos et al, 2012, Vogt et al, 2005, Geesmann et al, 2014, Cho, 2014, Burke, 2001, Baranauskas et al, 2015, Deutz et al, 2000, Barrero et al, 2014, Praz et al, 2014, Thomas et al, 2016. Studies capturing external training loads of Australian Football athletes have shown an average of 7323 ±2853 m per session ~25 % of which is high velocity running (>14.4 km/h) (O'Connor et al, 2020). Given team sport athletes routinely undertake prolonged bouts of high intensity training, inadequate energy intake is likely to induce an energy deficit leading to compromised muscle glycogen concentrations and low energy availability (Vigh-Larsen et al, 2021, Routledge et al, 2019.…”