Baker's yeast beta glucan supplementation increases salivary IgA and decreases cold/flu symptomatic days after intense exercise.

Strenuous exercise, such as running a marathon, is known to suppress mucosal immunity for up to 24 hr, which can increase the risk of developing an upper respiratory tract infection (URTI) and reduced performance capacity (Allgrove JE, Geneen L, Latif S, Gleeson M. Influence of a fed or fasted state on the s-IgA response to prolonged cycling in active men and women. Int J Sport Nutr Exerc Metab.

Repeated endurance exercise affects leukocyte number but not NK cell activity.

Introduction/purpose: The purpose of this study was to determine the affects of repeated bouts of exercise in the same day on circulating leukocyte number and NK cell activity (NKCA).

Methods: Ten males (18-25 yr of age) were chosen to complete four trials: two exercise bouts (TB), AM exercise (AM-EX), PM exercise (PM-EX), and control (CN) in a random, counter-balanced order. Exercise consisted of 1-h cycle ergometry, split into three, 20-min segments (5 min at 50% [V0](2peak) and 15 min at 70% [V0](2peak)), and was separated by a 4-h passive recovery.