Tags

Type your tag names separated by a space and hit enter

Thermoregulatory responses to exercise in the heat: chronic caffeine intake has no effect.
Aviat Space Environ Med 2006; 77(2):124-9AS

Abstract

INTRODUCTION

Authorities advise individuals to refrain from caffeine intake before or during exercise, especially when performed in the heat, due to potential fluid-electrolyte imbalances that exaggerate physiological strain. Yet, military personnel are often deployed to hot environments and must perform under sleep-deprived conditions where caffeine would be an ideal intervention strategy to enhance physical and cognitive performance.

PURPOSE

To assess the effects of controlled chronic and acute caffeine ingestion on fluid-electrolyte, physiological and thermoregulatory responses during an exercise heat tolerance test (EHT).

METHODS

Subjects were 59 active, college-aged males (mean +/- SE 21.6 +/- 0.4 yr, 177.9 +/- 0.8 cm, 75.4 +/- 1.0 kg, 11.1 +/- 0.7% body fat) who were randomized and stratified by age, bodyweight, and body composition into three groups. All subjects equilibrated caffeine intake at 3 mg x kg(-1) x d(-1) for days 1-6. On days 7-12, they consumed a treatment dose of either 0 (G0), 3 (G3), or 6 (G6) mg x kg(-1) x d(-1). Fluid-electrolyte and physiological measures were made on day 12, 1 h after caffeine intake, during the EHT (90 min walking, 1.56 m x s(-1), 5% grade; dry bulb temperature, 37.7 +/- 0.1 degree C; relative humidity, 56.3 -1.5%).

RESULTS

There were no between-group differences (p > 0.05) in plasma, urinary, thermoregulatory, cardiovascular, and perceptual variables across time (pre- vs. post-EHT), although some of these variables increased significantly over time (p < 0.05). EHT time was significantly greater in G3 (86 +/- 2.0 min) vs. GO (75 +/- 3.3 min, p < 0.05).

DISCUSSION

Acute caffeine ingestion, in chronically consuming subjects (3 and 6 mg x kg(-1) x d(-1)) did not alter fluid-electrolyte, exercise endurance or thermoregulatory responses during EHT when compared with G0.

Authors+Show Affiliations

The University of Connecticut, Human Performance Laboratory and Department of Kinesiology, Storrs, CT, USA. mroti@wsc.ma.eduNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

16491580

Citation

Roti, Melissa W., et al. "Thermoregulatory Responses to Exercise in the Heat: Chronic Caffeine Intake Has No Effect." Aviation, Space, and Environmental Medicine, vol. 77, no. 2, 2006, pp. 124-9.
Roti MW, Casa DJ, Pumerantz AC, et al. Thermoregulatory responses to exercise in the heat: chronic caffeine intake has no effect. Aviat Space Environ Med. 2006;77(2):124-9.
Roti, M. W., Casa, D. J., Pumerantz, A. C., Watson, G., Judelson, D. A., Dias, J. C., ... Armstrong, L. E. (2006). Thermoregulatory responses to exercise in the heat: chronic caffeine intake has no effect. Aviation, Space, and Environmental Medicine, 77(2), pp. 124-9.
Roti MW, et al. Thermoregulatory Responses to Exercise in the Heat: Chronic Caffeine Intake Has No Effect. Aviat Space Environ Med. 2006;77(2):124-9. PubMed PMID: 16491580.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Thermoregulatory responses to exercise in the heat: chronic caffeine intake has no effect. AU - Roti,Melissa W, AU - Casa,Douglas J, AU - Pumerantz,Amy C, AU - Watson,Greig, AU - Judelson,Daniel A, AU - Dias,Joao C, AU - Ruffin,Katherine, AU - Armstrong,Lawrence E, PY - 2006/2/24/pubmed PY - 2006/5/4/medline PY - 2006/2/24/entrez SP - 124 EP - 9 JF - Aviation, space, and environmental medicine JO - Aviat Space Environ Med VL - 77 IS - 2 N2 - INTRODUCTION: Authorities advise individuals to refrain from caffeine intake before or during exercise, especially when performed in the heat, due to potential fluid-electrolyte imbalances that exaggerate physiological strain. Yet, military personnel are often deployed to hot environments and must perform under sleep-deprived conditions where caffeine would be an ideal intervention strategy to enhance physical and cognitive performance. PURPOSE: To assess the effects of controlled chronic and acute caffeine ingestion on fluid-electrolyte, physiological and thermoregulatory responses during an exercise heat tolerance test (EHT). METHODS: Subjects were 59 active, college-aged males (mean +/- SE 21.6 +/- 0.4 yr, 177.9 +/- 0.8 cm, 75.4 +/- 1.0 kg, 11.1 +/- 0.7% body fat) who were randomized and stratified by age, bodyweight, and body composition into three groups. All subjects equilibrated caffeine intake at 3 mg x kg(-1) x d(-1) for days 1-6. On days 7-12, they consumed a treatment dose of either 0 (G0), 3 (G3), or 6 (G6) mg x kg(-1) x d(-1). Fluid-electrolyte and physiological measures were made on day 12, 1 h after caffeine intake, during the EHT (90 min walking, 1.56 m x s(-1), 5% grade; dry bulb temperature, 37.7 +/- 0.1 degree C; relative humidity, 56.3 -1.5%). RESULTS: There were no between-group differences (p > 0.05) in plasma, urinary, thermoregulatory, cardiovascular, and perceptual variables across time (pre- vs. post-EHT), although some of these variables increased significantly over time (p < 0.05). EHT time was significantly greater in G3 (86 +/- 2.0 min) vs. GO (75 +/- 3.3 min, p < 0.05). DISCUSSION: Acute caffeine ingestion, in chronically consuming subjects (3 and 6 mg x kg(-1) x d(-1)) did not alter fluid-electrolyte, exercise endurance or thermoregulatory responses during EHT when compared with G0. SN - 0095-6562 UR - https://www.unboundmedicine.com/medline/citation/16491580/Thermoregulatory_responses_to_exercise_in_the_heat:_chronic_caffeine_intake_has_no_effect_ L2 - https://www.ingentaconnect.com/openurl?genre=article&amp;issn=0095-6562&amp;volume=77&amp;issue=2&amp;spage=124&amp;aulast=Roti DB - PRIME DP - Unbound Medicine ER -