Effects of carbohydrate beverage ingestion on the salivary IgA response to intermittent exercise in the heat.

The purpose of this study was to establish if provision of CHO altered the mucosal immune and salivary cortisol responses to intermittent exercise in the heat. In a double-blind design, 10 males undertook soccer-specific intermittent exercise on a motorized treadmill on 2 occasions, each over 90 min and separated by 1 week. During CHO and placebo trials, subjects were given either a carbohydrate solution (3 ml · kg (-1) body weight) or placebo drink, 5 min before the commencement of exercise, at 15, 30 min, at half time, 60 and 75 min into exercise. Salivary flow rate increased throughout the placebo trial and decreased throughout the CHO treatment; the difference between conditions neared statistical significance (P=0.055). Neither s-IgA concentration nor s-IgA to osmolality ratio was affected by 2 conditions or differed at any time-point post-exercise (P>0.05). The s-IgA secretion rate increased, s-IgA to protein ratio decreased post-exercise and salivary cortisol decreased 24 h post-exercise (P<0.05) compared to pre-exercise. Carbohydrate supplementation whilst exercising in the heat, does not influence rating of perceived exertion, thermal sensation, salivary flow rate, s-IgA concentration, s-IgA secretion rate, s-IgA to osmolality ratio or s-IgA to protein ratio and salivary cortisol but heart rate was increased.

Effects of repeated bouts of soccer-specific intermittent exercise on salivary IgA.

Failure to recover fully between sessions has been suggested to cause immunodepression. Therefore, the cumulative effects of soccer-specific intermittent exercise undertaken on different days 48 h apart on salivary IgA, cortisol and total protein concentration were investigated. Nine male subjects completed two trials of soccer-specific intermittent exercise 48 h apart on a motorised treadmill. Timed unstimulated saliva samples were collected immediately before and after exercise, and 24 and 48 h post-exercise. Salivary IgA concentration (EX (1): 215 +/- 160 to 335 +/- 246 and EX (2): 144 +/- 93 to 271 +/- 185 mg . l (-1), p = 0.007), osmolality (p = 0.001) and total protein (p = 0.001) increased immediately following exercise in both trials and decreased 24 h afterwards, whereas saliva flow rate decreased significantly (p = 0.015) before returning to pre-exercise values 24 h postexercise. The IgA secretion rate, IgA to osmolality ratio, IgA to total protein, solute secretion rate, total protein secretion rate, and cortisol did not differ between the time-points. The results suggest that performing two bouts of moderate intensity soccer-specific intermittent exercise 48 h apart does not suppress resting salivary IgA concentration significantly although a small progressive reduction in salivary IgA was observed. These findings may not extend to successive competitive soccer games when vulnerable players might experience clinically relevant reductions in s-IgA.

Salivary IgA response to intermittent and continuous exercise.

Current evidence would support a view that intense exercise increases whereas moderate exercise reduces the susceptibility to illness, predominately upper respiratory tract infections. Concentrations of IgA and cortisol in saliva may be used to reflect changes in immune function. The aim of this study was to determine if the type of exercise (soccer-specific intermittent or continuous exercise at the same average work-rate and duration) affects salivary IgA (s-IgA) and cortisol responses. In a randomized, counterbalanced design, eight healthy males completed two trials one week apart at the same time of day on a motorized treadmill. One session entailed soccer-specific intermittent exercise, the other involved continuous exercise at the same overall work-rate. Diet and activity were standardized for 48 hours prior to and following each trial. Unstimulated saliva samples were collected via passive expectoration during the week prior to commencement of exercise, before, at half-time, immediately post-exercise, and 6 hours, 24 hours, and 48 hours post-exercise. No significant difference was observed in heart rate between the two exercise conditions (Intermittent: 142 +/- 14; Continuous: 141 +/- 16 beats x min (-1)). Average rating of perceived exertion was higher (p < 0.05) in intermittent exercise (11.9 +/- 0.8) than during continuous exercise (10.8 +/- 1.2). The pattern of change in salivary responses, including solute secretion rate, IgA concentration, IgA secretion rate, IgA to osmolality ratio, cortisol, and cortisol secretion rate did not differ between the two trials (p > 0.05). Concentrations of s-IgA for the intermittent and continuous protocols were 131.6 +/- 61.2 vs. 146.4 +/- 107.6 before, 148.4 +/- 82.5 vs. 229.2 +/- 159.6 after, and 125 +/- 78.7 vs. 131.1 +/- 80.7 48 h post-exercise, respectively. Saliva flow rate decreased and osmolality increased significantly across all time points (p < 0.05). In conclusion, soccer-specific intermittent exercise did not suppress the salivary IgA response or alter cortisol secretion compared to continuous exercise performed at the same overall work-rate.