Acute Naproxen Dose on Hydration and Electrolyte Measures During Moderate-Intense Exercise in the Heat

An abstract of a study by Emerson et al determining acute dose effects of a commonly used over the counter non-steroidal anti-inflammatory drugs, naproxen, on fluid and electrolyte measures during moderate-intense endurance exercise in a hot or ambient environment is presented. Results show no statistically significant differences between experimental trials for hydration, electrolyte, or cardiovascular measures. All participants began data collection euhydrated (mean Posm = 286 + 6.4 mOsm/L) and maintained hydration throughout exercise and rest. Mean aggregate plasma sodium (PNa) was < 135 mmol/L at pre, post-, and 3 hours post-exercise and did not significantly change over time. Aggregate plasma potassium concentration (PK) significantly increased pre- to post-exercise (3.9 + 0.4 to 4.2 + 0.4 mmol/L, P = 0.02). Compared to placebo trials, naproxen trials at post-exercise had higher PK, lower PNa, and lower Posm. Similarly, mean Fvol during exercise and total was higher and Uvol was lower in naproxen trials compared to placebo trials.