Evaluation of bathing with and without acute bouts of exercise at salivary levels of α-amylase and IgA in men

Abstract

Introduction: Evaluating how bathing influences various aspects of physiological responses is necessary to understand comprehensive mental and physical stress-related responses in humans. Although previous studies have argued effects of bathing on stress-related physiological responses, such as exercise-induced immunosuppression, salivary responses to bathing after exercise still remain unclear. The purpose of this study was to determine the effects of bathing with and without acute bouts of exercise on salivary levels of -amylase and IgA in men. Methods: Twelve recreationally active male collegiate students [age: 20.5±1.1 year; height: 169.6±6.8 cm; body mass: 63.1±6.9 kg; BMI: 22.0±2.7 kg/m2; body fat: 15.4±4.7% (mean± SD)] served as the subjects. The protocols consisted of two trials, which are: either (i) exercise (5min warm-up, 30 times of sit-ups, push-ups, and back-extensions, followed by 8 times of 40m sprint with 5min cool-down) plus bathing (E +B) or (ii) only bathing (B). Two experimental trials were performed on two different occasions separated by seven days under similar environmental conditions. Unstimulated saliva samples were collected within 10minutes before (Pre) and after (Post) each trial for analysis of salivary -amylase (a marker for a sensitive biomarker for stress-related changes in the body which reflect the sympathetic nervous system activity) and IgA (a marker for the incidence of URTI) and levels. Salivary -amylase and IgA levels were determined by an enzymatic assay and turbidimetric immunoassay, respectively. Results: In light of salivary -amylase activity, two-way analysis of variance (ANOVA) showed no significant main effects of time and intervention or interactions (Pre =181.6±157.9, Post = 228.7± 110.2 for E +B; Pre =246.3±205.2, Post = 198.7±125.5U/mL for B) before and after each trial. Furthermore, ANOVA for salivary IgA concentration demonstrated similar patterns (no significant maineffects of timeand interventionor interactions; Pre =8.2±2.5, Post = 10.6±3.5 for E +B; Pre =7.6±3.3, Post = 9.4±4.4mg/dL for B). Discussion: Previous studies have reported the effects of bathing on the recovery from fatigue following exercise. However, a paucity of data has been available concerning salivary responses to bathing after exercise-induced stress. The findings of the present study indicate that there appears to be similar salivary responses regardless of having short-duration exercise intervention, which implies thatbathing followingacuteboutsof exercise seems tohave had potential recovery from fatigue.