HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Graham, T. E. Articles by Richter, E. A. Search for Related Content PubMed PubMed Citation Articles by Graham, T. E. Articles by Richter, E. A.

Caffeine ingestion does not alter carbohydrate or fat metabolism in human skeletal muscle during exercise

Terry E. Graham*, Jorn W. Helge†, David A. MacLean‡, Bente Kiens† and Erik A. Richter†

1. This study examined the effect of ingesting caffeine (6 mg kg^-1) on muscle carbohydrate and fat metabolism during steady-state exercise in humans. Young male subjects (n = 10) performed 1 h of exercise (70 % maximal oxygen consumption (V_O2,max)) on two occasions (after ingestion of placebo and caffeine) and leg metabolism was quantified by the combination of direct Fick measures and muscle biopsies.

2. Following caffeine ingestion serum fatty acid and glycerol concentration increased (P <= 0·05) at rest, suggesting enhanced adipose tissue lipolysis.

3. In addition circulating adrenaline concentration was increased (P <= 0·05) at rest following caffeine ingestion and this, as well as leg noradrenaline spillover, was elevated (P <= 0·05) above placebo values during exercise.

4. Caffeine resulted in a modest increase (P <= 0·05) in leg vascular resistance, but no difference was found in leg blood flow.

5. Arterial lactate and glucose concentrations were increased (P <= 0·05) by caffeine, while the rise in plasma potassium was dampened (P <= 0·05).

6. There were no differences in respiratory exchange ratio or in leg glucose uptake, net muscle glycogenolysis, leg lactate release or muscle lactate, or glucose 6-phosphate concentration. Similarly there were no differences between treatments in leg fatty acid uptake, glycerol release or muscle acetyl CoA concentration.

7. These findings indicate that caffeine ingestion stimulated the sympathetic nervous system but did not alter the carbohydrate or fat metabolism in the monitored leg. Other tissues must have been involved in the changes in circulating potassium, fatty acids, glucose and lactate.

This article has been cited by other articles:

				A. Bassini-Cameron, E. Sweet, A. Bottino, C. Bittar, C. Veiga, L.-C. Cameron, and E. H M Dantas Effect of caffeine supplementation on haematological and biochemical variables in elite soccer players under physical stress conditions * COMMENTARY Br. J. Sports Med., August 1, 2007; 41(8): 523 - 530. [Abstract] [Full Text] [PDF]

				D. S. Battram, J. Bugaresti, J. Gusba, and T. E. Graham Acute caffeine ingestion does not impair glucose tolerance in persons with tetraplegia J Appl Physiol, January 1, 2007; 102(1): 374 - 381. [Abstract] [Full Text] [PDF]

				D. S. Battram, T. E. Graham, E. A. Richter, and F. Dela The effect of caffeine on glucose kinetics in humans - influence of adrenaline J. Physiol., November 15, 2005; 569(1): 347 - 355. [Abstract] [Full Text] [PDF]

				D. S. Battram, J. Shearer, D. Robinson, and T. E. Graham Caffeine ingestion does not impede the resynthesis of proglycogen and macroglycogen after prolonged exercise and carbohydrate supplementation in humans J Appl Physiol, March 1, 2004; 96(3): 943 - 950. [Abstract] [Full Text] [PDF]

				K. J. Conway, R. Orr, and S. R. Stannard Effect of a divided caffeine dose on endurance cycling performance, postexercise urinary caffeine concentration, and plasma paraxanthine J Appl Physiol, April 1, 2003; 94(4): 1557 - 1562. [Abstract] [Full Text] [PDF]

				V. Mougios, S. Ring, A. Petridou, and M. G. Nikolaidis Duration of coffee- and exercise-induced changes in the fatty acid profile of human serum J Appl Physiol, February 1, 2003; 94(2): 476 - 484. [Abstract] [Full Text] [PDF]

				J. M. Davis, Z. Zhao, H. S. Stock, K. A. Mehl, J. Buggy, and G. A. Hand Central nervous system effects of caffeine and adenosine on fatigue Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2003; 284(2): R399 - R404. [Abstract] [Full Text] [PDF]

				D. G. Bell and T. M. McLellan Exercise endurance 1, 3, and 6 h after caffeine ingestion in caffeine users and nonusers J Appl Physiol, October 1, 2002; 93(4): 1227 - 1234. [Abstract] [Full Text] [PDF]

				G. R. Cox, B. Desbrow, P. G. Montgomery, M. E. Anderson, C. R. Bruce, T. A. Macrides, D. T. Martin, A. Moquin, A. Roberts, J. A. Hawley, et al. Effect of different protocols of caffeine intake on metabolism and endurance performance J Appl Physiol, September 1, 2002; 93(3): 990 - 999. [Abstract] [Full Text] [PDF]

				F. S. L. Thong and T. E. Graham Caffeine-induced impairment of glucose tolerance is abolished by beta -adrenergic receptor blockade in humans J Appl Physiol, June 1, 2002; 92(6): 2347 - 2352. [Abstract] [Full Text] [PDF]

				F. S.L. Thong, W. Derave, B. Kiens, T. E. Graham, B. Urso, J. F.P. Wojtaszewski, B. F. Hansen, and E. A. Richter Caffeine-Induced Impairment of Insulin Action but Not Insulin Signaling in Human Skeletal Muscle Is Reduced by Exercise Diabetes, March 1, 2002; 51(3): 583 - 590. [Abstract] [Full Text] [PDF]

				F. Greer, R. Hudson, R. Ross, and T. Graham Caffeine Ingestion Decreases Glucose Disposal During a Hyperinsulinemic-Euglycemic Clamp in Sedentary Humans Diabetes, October 1, 2001; 50(10): 2349 - 2354. [Abstract] [Full Text]