The physiological stress induced by prolonged strenuous exercise, sleep-deprivation, exposure to environmental extremes, and nutrient deprivation has previously been reported to disturb host defences, with neuroendocrine responses being a key mechanism for this disturbance. Participating in activities that are associated with a combination of physiological stressors may amplify immune modulating neuroendocrine responses and induce greater disturbances to host defences. With this in mind, the purpose of this thesis was to investigate the effects of: 1. one night of total sleep-deprivation on selected immune ( circulating leukocyte trafficking, bacterially-stimulated neutrophil degranulation, saliva irnmunoglobulin A (IgA)) and stress hormone responses at rest and following prolonged strenuous exercise; 2. two nights of total sleep-deprivation with and without energy-restriction on selected immune and stress hormone responses at rest and after passive cold-exposure; 3. passive cold-exposure inducing modest reductions in whole-body core temperature on selected immune and stress hormone responses; and finally, 4. carbohydrate feeding with and without the addition of protein during recovery from prolonged strenuous exercise on selected immune, stress hormone and insulin responses. One night of total sleep-deprivation did not alter circulating leukocyte trafficking and plasma cortisol response, or compromise bacterially-stimulated neutrophil degranulation and saliva secretory IgA (S-IgA) responses at either rest or following prolonged strenuous exercise.
Two nights of total sleep-deprivation with and without a 90% energy-restriction did not alter circulating leukocyte trafficking and plasma stress hormone responses, or compromise bacterially-stimulated neutrophil degranulation and saliva S-IgA responses at rest. Passive cold-exposure alone decreased circulating lymphocyte counts, bacterially-stimulated neutrophil degranulation and saliva S-IgA responses. The addition of two nights of total sleep-deprivation with or without a 90% energy-restriction prior to cold exposure did not further amplify these immune perturbations. The ingestion of carbohydrate with and without the addition of protein immediately after prolonged strenuous exercise, in which only water was provided during exercise, prevented the decrease in bacterially-stimulated neutrophil degranulation during recovery. On the other hand, the provision of carbohydrate with and without protein immediately after prolonged strenuous exercise did not influence circulating leukocyte trafficking, stress hormone responses, or prevent the post-exercise decrease in saliva lgA concentration. It is possible that insulin response, and unlikely that stress hormone ( cortisol, catecholamines) responses, after carbohydrate ingestion with and without protein, may have a role in maintaining bacterially-stimulated neutrophil degranulation with immediate feeding after prolonged strenuous exercise, in which only water is provided during exercise.