|dc.description.abstract||The use of training in the heat to enhance performance has become a ‘hot topic’ in the world of elite sport given that a number of high profile events are held in hot environments, and emerging evidence suggests that training in the heat has the potential to be ergogenic. Short-term heat acclimation (HA) is a commonly used strategy to prepare athletes for competition in hot environments, but may also improve endurance performance in temperate conditions, enhance muscle strength and hypertrophy, and has been shown to increase sprint and power performance acutely. The majority of research used to establish our understanding of the acute physiological effects of heat and HA to date has been completed in untrained or moderately-trained individuals, with little work completed in well-trained or elite athletes. Thus, investigation into practical integration of HA or heat training into an elite athlete’s already busy training schedule, without interfering with key training sessions and competitions, is needed. Finally, most studies to date have tended to focus on performance measures relevant to long-duration, endurance exercise, and a greater understanding of how HA or heat training affects sprint performance is needed. Therefore, the primary aim of this thesis was to examine how the application of heat, through HA or heat training, might enhance physical performance. A secondary aim was to develop practical strategies that could be easily incorporated into the training programmes of elite athletes, including those competing in sprint and short duration power events.
To address these aims, four studies were conducted. Study 1 examined the retention of HA adaptations and re-acclimation (RA) responses during a periodised short-term HA protocol in elite sailors preparing for a World Championship competition in hot conditions. Study 2 examined the effects of a sprint cycling-specific heat training camp on sprint performance and physiological responses in elite sprint track cyclists in temperate conditions. As partial HA adaptations were shown in Study 2, the next study (Study 3) examined the acute effects of heat, as well as the effects of 5 d of sprint- and resistance training-based HA on repeated-sprint performance in elite BMX athletes. Based on the methods used in Studies 2 and 3, Study 4 aimed to determine the effects of a strength- and power-based resistance training session in the heat on thermal strain, neuromuscular function and hormonal responses in highly-trained power athletes.
Collectively, the studies contained within this thesis showed that HA and heat training can be strategically integrated into the complex training schedules of elite athletes and may effectively enhance physiological adaptations that support improved performance. The new findings included: 1) RA may ‘top-up’ thermoregulatory adaptations following initial HA and a 2-week period without heat exposure, 2) sprint performance is temporarily impaired following short-term heat training, despite partial HA and improved cardiovascular function, 3) BMX repeated-sprint performance is enhanced in the heat, notwithstanding increased thermal strain, and further HA improvements, and 4) power and anabolic hormone responses are elevated following a strength- and power-based resistance training session in the heat.||en_NZ