Exercise recovery and sleep characteristics in wheelchair court sports athletes

Evidence based approaches to sport science and medicine continue to evolve and grow within Paralympic sport. Nonetheless, areas that have implications for both health and performance, such as exercise recovery and sleep, are still underexplored. Yet importantly, athletes with certain impairments may have specific exercise recovery needs and experience more sleep difficulties depending on how their individual impairment interacts with these processes. Wheelchair court sports were amongst the earliest Paralympic events and are multi-impairment, intermittent-based sports. Medical conditions typically include but are not limited to spinal cord injuries, amputations, cerebral palsy, muscular dystrophy, peripheral neuropathy, and forms of skeletal dysplasia. Notably, the clinical literature suggests that many individuals with these medical conditions may be prone to sleep difficulties, which is pertinent given that sleep is a pillar that underpins the recovery process in athletic populations. In particular, athletes with a cervical spinal cord injury are at high risk of sleep disturbances. They represent a group that displays alterations in many physiological processes, including those related to autonomic function and thermoregulation. Despite the risk factors, the characterisation of exercise recovery and sleep in Paralympic athletes is limited. Therefore, this thesis aimed to set a foundation to understand these areas in Paralympic athletes by specifically targeting wheelchair court sports and athletes with a cervical spinal cord injury. Study one aimed to establish the prevalence of recovery strategy use in wheelchair courts sports and determine habitual habits relating to nutrition and sleep. A cross-sectional questionnaire was used to quantify this information. Of the one-hundred forty-four athletes that completed the questionnaire, 85% of the athletes reported using recovery strategies. "Active land-based", "stretching", and "nutrition" recovery strategies formed the top three types of recovery strategies used, while the prevalence of use was not influenced by impairment, age, sport, or gender. However, those who competed at an "elite" level used recovery strategies significantly more than the other respondents. Sleep difficulties were present among 38% of the wheelchair court sports athletes and were considerably high in those with a cervical spinal cord injury or amputation. Study two to four investigated sleep and circadian rhythms in wheelchair court sports athletes with a primary focus on athletes with a cervical spinal cord injury. Study two used objective (actigraphy) and subjective (sleep questionnaires) measures to determine sleep characteristics in highly trained wheelchair rugby athletes. Overall, the group was borderline between moderate to poor quality sleep reflected by suboptimal sleep characteristics. Group comparisons between the athletes with a cervical spinal cord injury and those without a spinal cord injury showed no differences in objective sleep. However, the athletes with a cervical spinal cord injury subjectively reported worse sleep across the sixteen-day study period. Study three measured circadian patterns of core body temperature, skin temperature, melatonin, and sleepiness in both athletes with a cervical spinal cord injury and able-bodied controls. In the cervical spinal cord injury group, the results highlighted that the core body temperature rhythm was phase-advanced, and the nocturnal melatonin response was blunted. Extending the findings from Study three, Study four sought to determine whether the physiological alterations observed impacted sleep in the athletes with a cervical spinal cord injury. Utilising the gold-standard method of sleep measurement, sleep characteristics did not differ between the athletes with a cervical spinal cord injury and the able-bodied controls when measured using polysomnography. Stage N2 sleep was the only sleep architecture variable that significantly differed between the two groups. Overall, it was concluded that sleep was comparable between the athletes with a cervical spinal cord injury and able-bodied controls despite the circadian differences in Study three. Study five A attempted to link the processes of recovery and sleep by investigating "athlete relevant" sleep loss on markers used to infer homeostatic recovery. Heart rate variability did not deviate from baseline outside a threshold range that indicated the smallest worthwhile change after a night of mild sleep restriction. Similarly, the cortisol awakening response and performance in several cognitive function tasks did not differ following the mild sleep restricted night compared to a habitual sleep night. Study five B was a short case report that investigated this question in two wheelchair court sports athletes with a cervical spinal cord injury. Parasympathetic tone consistently resided within the lower range for the athletes with a cervical spinal cord injury compared to the values obtained from the able-bodied individuals from Study five A. Nonetheless, the response to the mild sleep restriction protocol had similarities to the able-bodied individuals. The current thesis is the first to provide a comprehensive investigation of exercise recovery and sleep in Paralympic athletes. The body of research has indicated that suboptimal sleep may be prevalent in this population and should be considered by those working with these athletes. However, the current thesis used wheelchair court sports to access the population and identified athletes with a cervical spinal cord injury as the primary research interest group. Thus, future work should build on this foundation to investigate exercise recovery and sleep in other Paralympic sports and athletes. Furthermore, the circadian rhythm alterations identified in the current thesis should be investigated further in both clinical and athletic populations, given its wide ranging implications.