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The aim was to test the hypothesis that one night of sleep deprivation will impair pre-loaded 30 min endurance performance and alter the cardio-respiratory, thermoregulatory and perceptual responses to exercise. Eleven males completed two randomised trials separated by 7 days: once after normal sleep (496 (18) min: CON) and once following 30 h without sleep (SDEP). After 30 h participants performed a 30 min pre-load at 60% $$ \dot{V}{\text{O}}_{2\max } $$ followed by a 30 min self-paced treadmill distance test. Speed, RPE, core temperature (T re), mean skin temperature (T sk), heart rate (HR) and respiratory parameters ( $$ \dot{V}{\text{O}}_{2} $$ , $$ \dot{V}{\text{CO}}_{2} $$ , $$ \dot{V}{\text{E}} $$ , RER pre-load only) were measured. Less distance (P = 0.016, d = 0.23) was covered in the distance test after SDEP (6037 (759) 95%CI 5527 to 6547 m) compared with CON (6224 (818) 95%CI 5674 to 6773 m). SDEP did not significantly alter T re at rest or thermoregulatory responses during the pre-load including heat storage (0.8°C) and T sk. With the exception of raised $$ \dot{V}{\text{O}}_{2} $$ at 30 min on the pre-load, cardio-respiratory parameters, RPE and speed were not different between trials during the pre-load or distance test (distance test mean HR, CON 174 (12), SDEP 170 (13) beats min−1: mean RPE, CON 14.8 (2.7), SDEP 14.9 (2.6)). In conclusion, one night of sleep deprivation decreased endurance performance with limited effect on pacing, cardio-respiratory or thermoregulatory function. Despite running less distance after sleep deprivation compared with control, participants’ perception of effort was similar indicating that altered perception of effort may account for decreased endurance performance after a night without sleep.

A one night period without sleep is not uncommon amongst athletes travelling across time zones and military personnel during training and operations. However, the effect of one night without sleep on immune indices in response to strenuous exercise remains unknown. The objective was to determine the effect of one night without sleep on immune indices in response to subsequent strenuous exercise. Using a repeated measures cross-over design, on one occasion eleven male participants slept normally (CON) and on another they were sleep deprived for 30 h (SDEP). After 30 h participants performed 30 min steady state (SS) treadmill exercise at 60% VO2max followed by a 30 min treadmill time trial (TT). Blood and saliva samples were collected at 0 h, 30 h, post-SS, post-TT, 2 h post-TT and 18 h post-TT. Circulating leukocyte and T-lymphocyte subset counts, bacterially-stimulated neutrophil degranulation, saliva secretory immunoglobulin A (S-IgA) and plasma cortisol were determined. No trial x time interactions were observed for immune indices and plasma cortisol. A leukocytosis, neutrophilia, and lymphocytosis was observed post-TT compared with 30 h (P < 0.01). Also, at post-TT compared with 30 h an increase in circulating T-lymphocyte CD3 + (55%) and CD8 + (67%) counts (P < 0.05), a decrease in neutrophil degranulation (20%; P < 0.05) and an increase in S-IgA concentration (83%) was observed (P < 0.01). Plasma cortisol concentration increased post-TT (62%) compared with post-SS (P < 0.01). In conclusion, a 30 h period of sleep deprivation does not alter leukocyte trafficking, neutrophil degranulation or S-IgA responses either at rest or after submaximal and strenuous exercise.

The aim of this study was to determine the effects of prolonged exercise in hot conditions on saliva IgA (s-IgA) responses in trained cyclists. On two occasions, in random order and separated by 1 week, 12 male cyclists cycled for 2 h on a stationary ergometer at 62 (3)% VO2 max [194 (4) W; mean (SEM)], on one occasion (HOT: 30.3°C, 76% RH) and on another occasion (CONTROL: 20.4°C, 60% RH). Water was available ad-libitum. Venous blood samples and 2-min whole unstimulated saliva samples were collected at pre, post and 2 h post-exercise. The s-IgA concentration was determined using a sandwich-type ELISA. Exercising heart rate, rating of perceived exertion, rectal temperature, corrected body mass loss (P