An acute naproxen dose does not affect core temperature or Interleukin-6 during cycling in a hot environment

Dawn M Emerson; Stephen Cl Chen; Toni M Torres-McGehee; Craig E Pfeifer; Charles C Emerson; J Mark Davis

doi:10.1016/j.smhs.2021.08.004

An acute naproxen dose does not affect core temperature or Interleukin-6 during cycling in a hot environment

Sports Med Health Sci. 2021 Sep 1;3(4):243-251. doi: 10.1016/j.smhs.2021.08.004. eCollection 2021 Dec.

Authors

Dawn M Emerson¹, Stephen Cl Chen², Toni M Torres-McGehee³, Craig E Pfeifer⁴, Charles C Emerson⁵, J Mark Davis³

Affiliations

¹ Department of Physical Therapy, Rehabilitation Science, and Athletic Training, School of Health Professions, University of Kansas Medical Center, 3901 Rainbow Blvd, MS 2002, Kansas City, Kansas, 66 160, USA.
² Division of Exercise and Sport Science, Bob Jones University, 1700 Wade Hampton Blvd, Greenville, South Carolina, 29 614, USA.
³ Department of Exercise Science, Arnold School of Public Health, University of South Carolina, 921 Assembly Street, Columbia, SC, 29208, USA.
⁴ Applied Sport and Exercise Sciences, The Park, University of Gloucestershire, Cheltenham GL50 2RH, United Kingdom.
⁵ Department of Athletics, 5100 Rockhill Rd SRC 201, University of Missouri-Kansas City, Kansas City, Missouri, 64110, USA.

Abstract

Non-steroidal anti-inflammatory drugs' anti-pyretic and anti-inflammatory effects has led some individuals to theorize these medications may blunt core body temperature (Tc) increases during exercise. We utilized a double-blind, randomized, and counterbalanced cross-over design to examine the effects of a 24-h naproxen dose (3-220 mg naproxen pills) and placebo (0 mg naproxen) on Tc and plasma interleukin-6 (IL-6) concentrations during cycling in a hot or ambient environment. Participants (n = 11; 6 male, 5 female; age = 27.8 ± 6.5 years, weight = 79.1 ± 17.9 kg, height = 177 ± 9.5 cm) completed 4 conditions: 1) placebo and ambient (Control); 2) placebo and heat (Heat); 3) naproxen and ambient (Npx); and 4) naproxen and heat (NpxHeat). Dependent measures were taken before, during, and immediately after 90 min of cycling and then 3 h after cycling. Overall, Tc significantly increased pre- (37.1 ± 0.4 °C) to post-cycling (38.2 ± 0.3 °C, F _1.7,67.3 = 150.5, p < 0.001) and decreased during rest (37.0 ± 0.3 °C, F _2.0,81.5 = 201.6, p < 0.001). Rate of change or maximum Tc were not significantly different between conditions. IL-6 increased pre- (0.54 ± 0.06 pg/ml) to post-exercise (2.46 ± 0.28 pg/ml, p < 0.001) and remained significantly higher than pre-at 3 h post- (1.17 ± 0.14 pg/ml, 95% CI = -1.01 to -0.23, p = 0.001). No significant IL-6 differences occurred between conditions. A 24-h, over-the-counter naproxen dose did not significantly affect Tc or IL-6 among males and females cycling in hot or ambient environments.

Keywords: Cytokine; Exercise; Exertional heat illness; NSAIDs; Thermoregulation.