Effect of ambient temperature on caffeine ergogenicity during endurance exercise.
Summary of "Effect of ambient temperature on caffeine ergogenicity during endurance exercise."
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; [Formula: see text] 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% [Formula: see text]) 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, η(2) = 0.804, confidence interval (CI): 30.51-62.30]. When pooled, CAF increased performance versus PLA independent of temperature (P = 0.006, η(2) = 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 (T (re)) increased in the warm environment (peak T (re); 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.
Affiliation
Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT, 06269, USA, MatthewGanio@texashealth.org.
Journal Details
This article was published in the following journal.
Name: European journal of applied physiology
ISSN: 1439-6327
Pages:
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/21120518
- DOI: http://dx.doi.org/10.1007/s00421-010-1734-x
Medical and Biotech [MESH] Definitions
Exercise Tolerance
The exercise capacity of an individual as measured by endurance (maximal exercise duration and/or maximal attained work load) during an EXERCISE TEST.
Heating
The application of heat to raise the temperature of the environment, ambient or local, or the systems for accomplishing this effect. It is distinguished from HEAT, the physical property and principle of physics.
Caffeine
A methylxanthine naturally occurring in some beverages and also used as a pharmacological agent. Caffeine's most notable pharmacological effect is as a central nervous system stimulant, increasing alertness and producing agitation. It also relaxes SMOOTH MUSCLE, stimulates CARDIAC MUSCLE, stimulates DIURESIS, and appears to be useful in the treatment of some types of headache. Several cellular actions of caffeine have been observed, but it is not entirely clear how each contributes to its pharmacological profile. Among the most important are inhibition of cyclic nucleotide PHOSPHODIESTERASES, antagonism of ADENOSINE RECEPTORS, and modulation of intracellular calcium handling.
Exercise Test
Controlled physical activity, more strenuous than at rest, which is performed in order to allow assessment of physiological functions, particularly cardiovascular and pulmonary, but also aerobic capacity. Maximal (most intense) exercise is usually required but submaximal exercise is also used. The intensity of exercise is often graded, using criteria such as rate of work done, oxygen consumption, and heart rate.
Placebo Effect
An effect usually, but not necessarily, beneficial that is attributable to an expectation that the regimen will have an effect, i.e., the effect is due to the power of suggestion.
PubMed Articles
The effects of different doses of caffeine on endurance cycling time trial performance.
Abstract This study investigated the effects of two different doses of caffeine on endurance cycle time trial performance in male athletes. Using a randomised, placebo-controlled, double-blind cross...
Muscle Specific MicroRNAs are regulated by Endurance Exercise in Human Skeletal Muscle.
Muscle specific miRNAs, myomiRs, have been shown to control muscle development in vitro and are differentially expressed at rest in diabetic skeletal muscle. Therefore, we investigated the expression...
ABSTRACT: BACKGROUND: Calorie restriction (CR) and endurance exercise are known to attenuate obesity and improve the metabolic syndrome. The aim of this study was to directly compare the effects of CR...
The purpose of this study was to evaluate the mechanisms for improved exercise capacity after endurance exercise training (ET) in elderly patients with heart failure and preserved ejection fraction (H...
Aim: Several rodent and human studies revealed that physical exercise acts as a non-photic zeitgeber for the circadian clock. The intrinsic entraining mechanism is still unknown, although it was as...
Clinical Trials
The study investigated the effect of caffeine on physical performance in healthy citizens aged over 70 years following eight hours of abstinence from caffeine containing drinks and foods....
The Effect of Caffeine in Elderly Citizens
The study investigated the effect of caffeine on physical performance in healthy citizens aged over 70 years. The main hypothesis was that 6 mg/kg caffeine would improve cycling endurance...
Caffeine and Intermittent Claudication
The purpose of this study is to evaluate the change in Walking capacity after an intake of caffeine. The study design is cross-over and follow-up of 80 patients with leg pain caused by nar...
Trial Investigating the Effect of Different Exercise Forms on Depression
During one year, 5-8% of the population will suffer from major depression. Some of the key symptoms are loss of interest in daily activities, loss of energy and sleeping disturbances. The...
The Effect of Caffeine on Ischemic Preconditioning
Ischaemic preconditioning (IP) describes the phenomenon that brief periods of ischaemia render the (myocardial) muscle more resistant to a subsequent more prolonged period of ischaemia and...
