Date of Award


Document Type

Open Access Dissertation


Health Promotion, Education and Behavior


Norman J. Arnold School of Public Health

First Advisor

J. Mark Davis


Naproxen is a commonly used non-steroidal anti-inflammatory drug designed to relieve pain and inflammation. Due to potentially adverse effects on the gastrointestinal (GI) tract, cardiovascular and immune system, and renal function, naproxen may negatively affect thermoregulation, fluid and electrolyte balance, and performance during exercise, particularly in the heat. Therefore, the purpose of this study was to determine the effects of naproxen on core temperature (Tc), inflammation, hydration, GI distress, and performance during cycling in a hot environment. We utilized a double-blind, randomized and counterbalanced, cross-over design to determine the effects of naproxen (dose = 3 220 mg naproxen sodium pills) or placebo (3 cellulose pills) on the dependent variables: Tc, interleukin-6 (IL-6), GI distress symptoms, fecal occult blood, plasma sodium and potassium concentration, plasma osmolality, urine osmolality, urine specific gravity, percent change in body mass, urine volume, fluid volume, heart rate, blood pressure, rate of perceived exertion, and distance during a 10 min time trial. Participants (n = 11, age = 27.8 + 5.7 yrs, weight = 79.1 + 17.9 kg, and V̇O2max = 41.4 + 5.7 mL/kg) completed 4 conditions: 1) placebo and ambient (Control); 2) naproxen and ambient (Npx); 3) placebo and heat (Heat); and 4) naproxen and heat (NpxHeat) separated by a minimum of 7 days. Dependent measures were taken pre-, during, post-, and 3 hrs post- a 90 min cycling protocol. We found no statistically significant differences between experimental conditions for any dependent variable. Exercise induced significant overall increases pre- to post- for Tc, IL-6, plasma potassium, heart rate, blood pressure, perceived exertion, and GI distress. Compared to placebo, naproxen generally led to higher fluid intake and lower urine volume. Mean distance traveled was highest during Npx (3.3 + 0.8 miles) and lowest in NpxHeat (2.8 + 0.8 miles). Participants experienced greater GI distress during Heat, especially day post-exercise. During exercise, GI symptom occurred in 64% of trials. Interestingly, dizziness and headache were only reported during placebo conditions, with generally less systemic symptoms during exercise with naproxen use. In conclusion, our results do not support our hypotheses that naproxen would increase Tc, IL-6, and GI distress, alter fluid-electrolyte balance, and decrease performance compared to placebos.