The effect of exercise intensity and fluid restriction on cognitive function and salivary measures in Division III male and female endurance athletes
Backes, Todd Patrick
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It is well documented how even modest dehydration can be detrimental to physiological functions in endurance based athletic competition. Previous work has examined decreases in power output, force, and time to exhaustion as well as physiological variables such as the appearance of changes in hormone levels as they relate to success in various endurance sports/activities such as running, swimming, cycling and rowing. Success in athletic competition, however, is not solely limited to enhancing endurance aspects alone. Cognitive function plays an important role in competition. The purpose of this research is to examine the effect of exercise on the appearance of salivary alpha amylase, cortisol and testosterone and to examine the effect of exercise on cognitive function both under modest fluid restriction (<3% Body Weight). The subjects were NCAA Division III male and female athletes that participate in team based sports such as soccer, basketball, rugby and volleyball. Apparently healthy subjects were screened had aerobic fitness and body composition determined in the first of three lab visits. The second and third lab consisted of identical treadmill exercise paired with two different fluid interventions. Prior to the treadmill exercise and immediately after both moderate and high intensity exercise cognitive function was measured via the Automated Neuropsychological Assessment Metrics (ANAM) program. Saliva and urine collections were taken prior to the exercise and immediately following exercise termination. Five cognitive tests were selected from the ANAM test battery and analyzed. The results showed that cognition was impacted by the exercise protocol and fluid condition individually and by an interaction between the exercise protocol and fluid condition. Cognition was affected differently at moderate intensity exercise dependant on fluid condition. Cognition was also impacted by the gender of the subject. We demonstrate in this study that exercise, both moderate and high intensity, elicits a significant increase in salivary cortisol, salivary testosterone, and salivary alpha-amylase. This change was irrespective of fluid condition. Additionally, the fluid condition had an effect on cortisol and had an effect (along with gender) on alpha-amylase. Fluid condition effects were evident in females rather than males. For testosterone there was also an interaction effect of exercise and gender. This research is unique in its application to subjects who are involved in team based sports as well as using both male and female athletes. The use of both female and male athletes reveals results that support differences in suggested hydration strategies based on gender. Whereas previous work has looked at physiological responses to dehydration and performance skills independently, this research will use a very sophisticated measure of cognitive function along with the examination of physiological responses. This research can be the basis for future studies that focus on athletes who are involved in sports in which performance is based on reaction, and decision making.