Chronic administration of therapeutic levels of clenbuterol acts as a repartitioning agent.
Abstract: The purpose of this study was to examine the effect of therapeutic levels of clenbuterol, with and without exercise training, on body composition. Twenty-three unfit Standardbred mares were divided into four experimental groups: clenbuterol (2.4 microg/kg body wt twice daily) plus exercise (ClenEx; 20 min at 50% maximal oxygen consumption 3 days/wk; n = 6), clenbuterol only (Clen; n = 6), exercise only (Ex; n = 5), and control (Con; n = 6). Rump fat thickness was measured at 2-wk intervals by using B-mode ultrasound, and percent body fat (%fat) was calculated by using previously published methods. For Ex, body fat decreased (P < 0.05) at week 4 (-9.3%), %fat at week 6 (-6.9%), and fat-free mass (FFM) increased (P 0.05) in any variable at any time. These results suggest that exercise training and clenbuterol have additive effects with respect to %fat and fat mass but antagonistic effects in terms of FFM. Furthermore, chronic clenbuterol administration causes significant repartitioning in the horse, even when administered in therapeutic doses.
Publication Date: 2001-10-20 PubMed ID: 11641345DOI: 10.1152/jappl.2001.91.5.2064Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This study examines how therapeutic doses of clenbuterol, in conjunction with or without exercise, can affect body fat and muscle mass in horses. The study found that clenbuterol changes body composition, showing significant reduction in body fat and an increase in fat-free mass, even more so when combined with exercise.
Objective and Methodology
- The study’s primary aim was to investigate the effects of clenbuterol, a bronchodilator drug typically used in treating respiratory conditions, on body composition. The study also considered the combined effects of clenbuterol and physical exercise.
- 23 unfit Standardbred mares were divided into four groups: the ClenEx group (clenbuterol plus exercise), the Clen group (clenbuterol only), the Ex group (exercise only), and the Con group (control). Body fat and muscle mass changes were subsequently observed and recorded.
- Measurements taken included rump fat thickness (using B-mode ultrasound) and overall body fat percentage, using previously established methods.
Results
- The exercise-only group saw a reduction in body fat starting from the 4th week and a slight increase in Fat-Free Mass (FFM – a measurement of everything in the body excluding all fat) from the 8th week.
- The clenbuterol-only group had significant changes in the 2nd week: body fat percentage and overall fat mass significantly reduced, with a moderate FFM increase.
- The ClenEx group (clenbuterol and exercise) had notable decreases in body fat percentage and overall fat mass as early as the second week, similar to the clenbuterol-only group. However, this group saw a significant increase in FFM by the sixth week.
- The control group showed no changes during the entire research period.
Conclusion
- This research suggests that a combination of exercise and clenbuterol has a cumulative effect for fat loss but produces contrasting results for changes in FFM.
- Interestingly, administering therapeutic levels of clenbuterol resulted in significant “repartitioning”, showing it as an effective tool to adjust body fat and muscle mass.
- The findings suggest clenbuterol might be useful as a weight-loss or body-building agent when administered in measured doses.
Cite This Article
APA
Kearns CF, McKeever KH, Malinowski K, Struck MB, Abe T.
(2001).
Chronic administration of therapeutic levels of clenbuterol acts as a repartitioning agent.
J Appl Physiol (1985), 91(5), 2064-2070.
https://doi.org/10.1152/jappl.2001.91.5.2064 Publication
Researcher Affiliations
- Department of Animal Sciences, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, USA.
MeSH Terms
- Adipose Tissue / diagnostic imaging
- Adipose Tissue / physiology
- Adrenergic beta-Agonists / pharmacology
- Animals
- Body Composition / physiology
- Bronchodilator Agents / pharmacology
- Clenbuterol / pharmacology
- Female
- Horses / physiology
- Physical Conditioning, Animal / physiology
- Physical Exertion / physiology
- Time Factors
- Ultrasonography
Citations
This article has been cited 4 times.- Hu S, Yang G, Chen Z, Li Q, Liu B, Liu M, Zhang D, Chang S, Kong R. Docking guided phase display to develop fusion protein with novel scFv and alkaline phosphatase for one-step ELISA salbutamol detection.. Front Microbiol 2023;14:1190793.
- Waller P, Lomnicka I, Lucas C, Johnson S, Dirikolu L. The medication violations in racehorses at Louisiana racetracks from 2016 to 2020.. Vet Med Sci 2022 Mar;8(2):553-560.
- Knych HK, Harrison LM, Steinmetz SJ, Chouicha N, Kass PH. Differential expression of skeletal muscle genes following administration of clenbuterol to exercised horses.. BMC Genomics 2016 Aug 9;17:596.
- Plant DR, Kearns CF, McKeever KH, Lynch GS. Therapeutic clenbuterol treatment does not alter Ca2+ sensitivity of permeabilized fast muscle fibres from exercise trained or untrained horses.. J Muscle Res Cell Motil 2003;24(7):471-6.
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