The β2-adrenergic agonist, clenbuterol, has powerful muscle anabolic and lipolytic effects and is used by athletes to improve exercise performance; however, its use in conjunction with different forms of exercise training has received limited attention. Since previous studies have reported that chronic use of other β2-adrenergic agonists has deleterious effects on cardiac muscle structure and function, the aim of the present study was to determine whether chronic clenbuterol administration would reduce the exercise capabilities of rats subjected to long-term treadmill sprint running, endurance swimming or voluntary wheel running training. The effect of clenbuterol treatment on exercise performance in rats was evaluated in three separate studies. Different groups of male rats were assigned to an endurance swimming (2 h/day, 5/7 days, 18 weeks) group, a treadmill sprint running (8×1 min bouts, 1.05 m/s, 20 weeks) group, or a voluntary wheel running (16 weeks) group. In each study, rats were allocated into either a treated group that received clenbuterol (2 mg·kg-1·day-1) in their drinking water or an untreated control group. In each of the three studies, treated rats exhibited a reduction in exercise performance compared with untreated rats. Treated rats ran ∼ 57% less total distance than untreated rats in the voluntary running programme and were unable to complete the swimming and sprinting protocols performed by the untreated rats. In each of the studies, the treated rats exhibited cardiac hypertrophy, with absolute heart mass increased by ∼ 19% and heart mass relative to body mass increased by ∼ 20%. The hearts of sedentary rats treated with clenbuterol exhibited extensive collagen infiltration surrounding blood vessels and in the wall of the left ventricle. The results indicate strongly that chronic clenbuterol administration deleteriously affects exercise performance in rats, potentially due to alterations in cardiac muscle structure and function.
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March 2000
Research Article|
February 09 2000
Deleterious effects of chronic clenbuterol treatment on endurance and sprint exercise performance in rats
Noel D. DUNCAN;
Noel D. DUNCAN
1Department of Physiology, The University of Melbourne, Parkville, Victoria 3052, Australia
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David A. WILLIAMS;
David A. WILLIAMS
1Department of Physiology, The University of Melbourne, Parkville, Victoria 3052, Australia
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Gordon S. LYNCH
1Department of Physiology, The University of Melbourne, Parkville, Victoria 3052, Australia
Correspondence: Dr Gordon S. Lynch (e-mail g.lynch@physiology.unimelb.edu.au).
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Clin Sci (Lond) (2000) 98 (3): 339–347.
Article history
Received:
February 17 1999
Revision Received:
September 15 1999
Accepted:
October 25 1999
Citation
Noel D. DUNCAN, David A. WILLIAMS, Gordon S. LYNCH; Deleterious effects of chronic clenbuterol treatment on endurance and sprint exercise performance in rats. Clin Sci (Lond) 1 March 2000; 98 (3): 339–347. doi: https://doi.org/10.1042/cs0980339
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