Relationship Between Exercise Intensity And Voluntary Fluid Intake In Air Force Rotc Cadets

Air Force ROTC cadets are college students simultaneously receiving training to serve as officers in the United States Air Force. Regular group exercise is part of this training program, and good hydration habits would be conducive to optimizing the exercise sessions. However, it is unclear whether exercise intensity might influence this special population's voluntary drinking behaviors in a manner that is sufficient for optimizing exercise training sessions. PURPOSE: Therefore, the purpose of this study was to examine the relationship between exercise intensity and voluntary fluid intake in Air Force ROTC cadets during a typical training session. METHODS: Nine male and 2 female Air Force ROTC cadets (mean ± SD; age: 22 ± 3 y, height: 170.0 ± 5.1 cm, mass: 71.2 ± 9.5 kg) were fitted with heart rate (HR) monitors prior to exercise. Intensity was expressed as a percentage of HR reserve. A hydration station was set up in the exercise area where water bottles were made readily available. Fluid intake was calculated as the difference in the water bottle mass before and after the exercise session. RESULTS: During the 60-min exercise session, participants exercised at a moderate intensity based on a percentage of HR reserve (50.1 ± 10.2%) with a mean HR of 129 ± 15 beats·min-1. Mean voluntary fluid intake volume was 404.5 ± 168.2 mL. There was no correlation between fluid intake volume and exercise intensity (r = 0.186, p = 0.584). CONCLUSION: It is possible that another mechanism stronger than exercise intensity would stimulate the thirst mechanism to drive voluntary fluid intake. It is also possible the cadets did not have sufficient fluid breaks, although this was not tracked in the current study. This study lends further support of incorporating structured water breaks and individualized hydration strategies during exercise training, especially for cadets training to become tactical operators.