Oral supplementation with bovine colostrum (COL) has been shown to enhance immunity in human subjects. However, there is limited research on the use of bovine COL supplementation to counter exercise-induced immunodepression, as a model of stress-induced immunodepression, and previous research has focused primarily on salivary IgA. The aim of the present study was to determine the effects of bovine COL supplementation on exercise-induced changes in innate immunity (neutrophil function and salivary lysozyme) in addition to salivary IgA. Twenty healthy, active men cycled for 2 h at approximately 64 % maximal oxygen uptake after 4 weeks of daily bovine COL (n 10) or placebo (PLA, n 10) supplementation. Blood and saliva samples were obtained before and after supplementation, before and after exercise. Exercise induced significant increases in markers of physiological stress and stress to the immune system (circulating neutrophils, neutrophil:lymphocyte ratio, immature granulocytes, atypical lymphocytes and plasma cortisol), but there were no differences between the COL and PLA groups. Significant group x time interactions (two-way mixed model ANOVA) were observed for neutrophil function (stimulated degranulation) and salivary lysozyme concentration and release (P < 0.05). Significant exercise-induced decreases were observed in these parameters, and bovine COL supplementation either speeded the recovery (neutrophil function) or prevented the decrease (salivary lysozyme) in these measures of innate immunity. These results suggest that 4 weeks of bovine COL supplementation limits the immunodepressive effects induced by an acute prolonged physical stressor, such as exercise, which may confer some benefits to host defence.

The aim of this work was to investigate the effect of a daily mixed nutritional supplement upon body composition, physical performance, and circulating anabolic hormones in soldiers undergoing arduous training. Thirty males received either a habitual diet alone (CON, n = 15) or with the addition of a daily mixed supplement (SUP, n = 15) of ∼5.1 MJ·d⁻¹ during 8 weeks of training. Body composition (DEXA), maximal dynamic lift strength (MDLS), and vertical jump (VJ) were assessed, and resting blood samples were collected before and after training. Blood analysis included insulin-like growth factors (IGF-1, IGF BP-1, and IGF BP-3), testosterone, and cortisol. There were no group differences at baseline. Body mass loss (mean ± SD) (CON 5.0 ± 2.3, SUP 1.6 ± 1.5 kg), lean mass loss (CON 2.0 ± 1.5, SUP 0.7 ± 1.5 kg), and fat mass loss (CON 3.0 ± 1.6, SUP 0.9 ± 1.8 kg) were significantly blunted by SUP. CON experienced significant decrements in MDLS (14%), VJ (10%), and explosive leg power (11%) that were prevented by SUP. Military training significantly reduced circulating IGF-1 (28%), testosterone (19%), and the testosterone:cortisol ratio (24%) with no effect of SUP. Circulating IGF BP-1 concentration and cortisol remained unchanged throughout, although SUP abolished the significant decrease in circulating IGF BP-3 (20%) on CON. In conclusion, a daily mixed nutritional supplement attenuated decreases in body mass and lean mass and prevented the decrease in physical performance during an arduous military training program.

T(osm) increased with dehydration and tracked alterations in P(osm) with comparable utility to USG. Measuring T(osm) using the TearLab osmolarity system may offer sports medicine practitioners, clinicians, and research investigators a practical and rapid hydration assessment technique.

The aim of the study was to investigate the effect of exercise-induced dehydration and subsequent overnight fluid restriction on saliva antimicrobial proteins important for host defence (secretory IgA (SIgA), α-amylase, and lysozyme). On two randomized occasions, 13 participants exercised in the heat, either without fluid intake to evoke progressive body mass losses (BML) of 1%, 2%, and 3% with subsequent overnight fluid restriction until 0800 h in the following morning (DEH) or with fluids to offset losses (CON). Participants in the DEH trial rehydrated from 0800 h until 1100 h on day 2. BML, plasma osmolality (Posm), and urine specific gravity (USG) were assessed as hydration indices. Unstimulated saliva samples were assessed for flow rate (SFR), SIgA, α-amylase, and lysozyme concentrations. Posm and USG increased during dehydration and remained elevated after overnight fluid restriction (BML = 3.5% ± 0.3%, Posm = 297 ± 6 mosmol·kg⁻¹, and USG = 1.026 ± 0.002; P < 0.001). Dehydration decreased SFR (67% at 3% BML, 70% at 0800 h; P < 0.01) and increased SIgA concentration, with no effect on SIgA secretion rate. SFR and SIgA responses remained unchanged in the CON trial. Dehydration did not affect α-amylase or lysozyme concentration but decreased secretion rates of α-amylase (44% at 3% BML, 78% at 0800 h; P < 0.01) and lysozyme (46% at 3% BML, 61% at 0800 h; P < 0.01), which were lower than in CON at these time points (P < 0.05). Rehydration returned all saliva variables to baseline. In conclusion, modest dehydration (~3% BML) decreased SFR, α-amylase, and lysozyme secretion rates. Whether the observed magnitude of decrease in saliva AMPs during dehydration compromises host defence remains to be shown.

14Carbohydrate (CHO) supplementation during prolonged exercise is widely acknowledged to 15 blunt in vitro immunoendocrine responses but no study has investigated in vivo immunity. 16Purpose: To determine the effect of CHO supplementation during prolonged exercise on in 17 vivo immune induction using experimental contact hypersensitivity (CHS) with the novel 18 antigen Diphenylcyclopropenone (DPCP). 19Methods: In a double-blind design, 32 subjects were randomly assigned to 120 minutes of 20 treadmill exercise at 60% ̇O 2max with CHO (Ex-CHO) or placebo (Ex-PLA) 21 supplementation. Responses were also compared to 16 resting control (CON) subjects from a 22 previous study (for additional comparison with a resting non-exercise condition). 23Standardised diets (24 h pre-trial) and breakfasts (3.5 h pre-trial) were provided. Subjects