Clenbuterol and Aerobic capacity

[prolangtum]

This definitley shows a decrease:

KEARNS, C. F., and K. H. MCKEEVER. Clenbuterol diminishes aerobic performance in horses., Vol. 34, No. 12, pp. 1976-1985, 2002.PURPOSE The purpose of this 8-wk study was to examine the effect of therapeutic levels of clenbuterol on aerobic performance and hemodynamics associated with exercise.METHODS Twenty-three unfit Standardbred mares were divided into four experimental groups, clenbuterol (2.4 &mgr;g.kg body weight twice daily) plus exercise (20 min at 50% [OV0312]O; CLENEX; = 6), clenbuterol only (CLEN; = 6), exercise only (EX; = 5), and control (CON; = 6). All horses performed an incremental exercise test (GXT) to measure maximal oxygen consumption ([OV0312]O ), blood lactate concentration, total plasma protein concentration, and hematocrit. Plasma volume, heart rate, right ventricular pressure (RVP), and pulmonary artery pressure (PAP) were measured before and after the treatment/training. Each horse also performed an exercise capacity test (ECT) in which they ran at their pretreatment [OV0312]O speed until exhausted.(2max) (2max) (2max)RESULTS There were no significant changes in blood lactate, total protein, or hematocrit for any group during either the GXT or ECT. CLENEX decreased ( < 0.05) [OV0312]O (-6.2%) and velocity to [OV0312]O (-10.0%), whereas both CLENEX and CLEN decreased ( < 0.05) in time to exhaustion (-20.5 +/- 4.7 and -20.9 +/- 5.6%). EX alone increased ( < 0.05) [OV0312]O (+6.5%), velocity to [OV0312]O (+10.0%), velocity to produces lactate concentration of 4 mmol (+13.5%), and time to exhaustion (+32.3 +/- 15.0%). Plasma volume was altered ( < 0.05) in CLENEX (-10%) and EX (+27%) but not in CLEN. Posttest recovery HR was higher ( < 0.05) at 2 min post-GXT in the CLENEX, CLEN, and CON compared with their pretest values; RVP remained elevated at 2 min of recovery in the CLEN and CON groups; however, in the EX, recovery HR and RVP had returned to pre-GXT levels by 2 min of recovery.(2max) (2max) (2max) (2max)CONCLUSIONS These data suggest that the combined effect of therapeutic levels of clenbuterol and training decrease aerobic performance and that the resultant reduction in plasma volume may affect improvements in cardiovascular function during recovery normally seen with exercise training.

PMID: 12471305 [PubMed - as supplied by publisher]

[prolangtum]

This shows it in mice, but doses were a little high:

Interaction between clenbuterol and run training: effects on exercise performance and MLC isoform content.

Ingalls CP, Barnes WS, Smith SB.

Department of Health, Texas A&M University, College Station 77843, USA.

The purpose of this study was to determine the separate and combined effects of clenbuterol (CB) administration and interval training on running performance and myosin light-chain (MLC) isoform expression in mouse skeletal muscle. Mice were randomly assigned to one of four treatment groups: 1) control (Con), 2) exercise (Ex), 3) drug (CB), or 4) exercise + drug (Ex + CB). CB and Ex + CB mice were given CB (1.6 mg/kg) orally 4 days/wk. Ex and Ex + CB mice were trained 4 days/wk on a motorized treadmill (3 sets of 3 min, 36-40 m/min, 10-17% grade, 30-s recovery). After 8 wk of treatment, exercise conditioning increased total work performed 58% in the Ex group during a run-to-exhaustion treadmill test, whereas CB decreased total work by 25% in the CB group; in combination with exercise training, CB treatment eliminated the Ex-induced increase in work. Polyacrylamide gel electrophoresis indicated that run training, CB treatment, or a combination did not (P > 0.01) promote changes in fast and slow MLC isoforms in the soleus, gastrocnemius, or tibialis anterior muscles. Although not different from each other after 8 wk, CB and Ex + CB treatments produced significantly greater values than Con and Ex for the following variables: muscle mass (17-46%), total protein (22-50%), and myofibrillar protein (19-53%). It was concluded that CB decreases exercise performance and that the combination of Ex and CB have antagonistic effects on running performance; the two treatments do not interact to diminish the anabolic effects of CB on skeletal muscle and do not alter MLC isoform profiles.

[scorpion]

Good post pro............I dislike thermogenics [and broncile dialators] anyways