European Journal of Applied Physiology

, Volume 111, Issue 6, pp 1135–1146

Effect of ambient temperature on caffeine ergogenicity during endurance exercise

  • Matthew S. Ganio
  • Evan C. Johnson
  • Jennifer F. Klau
  • Jeffrey M. Anderson
  • Douglas J. Casa
  • Carl M. Maresh
  • Jeff S. Volek
  • Lawrence E. Armstrong
Original Article

DOI: 10.1007/s00421-010-1734-x

Cite this article as:
Ganio, M.S., Johnson, E.C., Klau, J.F. et al. Eur J Appl Physiol (2011) 111: 1135. doi:10.1007/s00421-010-1734-x

Abstract

It is well established that caffeine ingestion during exercise enhances endurance performance. Conversely, the physiological and psychological strain that accompanies increased ambient temperature decreases endurance performance. Little is known about the interaction between environmental temperature and the effects of caffeine on performance. The purpose of this study was to compare the effects of ambient temperature (12 and 33°C) on caffeine ergogenicity during endurance cycling exercise. Eleven male cyclists (mean ± SD; age, 25 ± 6 years; \( {\dot V \text{O}}_{2\max } , \) 58.7 ± 2.9 ml kg−1 min−1) completed four exercise trials in a randomized, double blind experimental design. After cycling continuously for 90 min (average 65 ± 7% \( {\dot V \text{O}}_{2\max } \)) in either a warm (33 ± 1°C, 41 ± 5%rh) or cool (12 ± 1°C, 60 ± 7%rh) environment, subjects completed a 15-min performance trial (PT; based on total work accumulated). Subjects ingested 3 mg kg−1 of encapsulated caffeine (CAF) or placebo (PLA) 60 min prior to and after 45 min of exercise. Throughout exercise, subjects ingested water so that at the end of exercise, independent of ambient temperature, their body mass was reduced 0.55 ± 0.67%. Two-way (temperature × treatment) repeated-measures ANOVA were conducted with alpha set at 0.05. Total work (kJ) during the PT was greater in 12°C than 33°C [P < 0.001, η2 = 0.804, confidence interval (CI): 30.51–62.30]. When pooled, CAF increased performance versus PLA independent of temperature (P = 0.006, η2 = 0.542 CI: 3.60–16.86). However, performance differences with CAF were not dependent on ambient temperature (i.e., non-significant interaction; P = 0.662). CAF versus PLA in 12 and 33°C resulted in few differences in other physiological variables. However, during exercise, rectal temperature (Tre) increased in the warm environment (peak Tre; 33°C, 39.40 ± 0.45; 12°C, 38.79 ± 0.42°C; P < 0.05) but was not different in CAF versus PLA (P > 0.05). Increased ambient temperature had a detrimental effect on cycling performance in both the CAF and PLA conditions. CAF improved performance independent of environmental temperature. These findings suggest that caffeine at the dosage utilized (6 mg/kg body mass) is a, legal drug that provides an ergogenic benefit in 12 and 33°C.

Keywords

Thermal stressHyperthermiaEnvironmental temperature

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Matthew S. Ganio
    • 1
    • 2
  • Evan C. Johnson
    • 1
  • Jennifer F. Klau
    • 1
  • Jeffrey M. Anderson
    • 1
  • Douglas J. Casa
    • 1
  • Carl M. Maresh
    • 1
  • Jeff S. Volek
    • 1
  • Lawrence E. Armstrong
    • 1
  1. 1.Human Performance Laboratory, Department of KinesiologyUniversity of ConnecticutStorrsUSA
  2. 2.Texas Health Resources Presbyterian Hospital DallasInstitute for Exercise and Environmental MedicineDallasUSA