Acute Effects Of Marihuana Smoking On Maximal Exercise Performance

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Abstract
To evaluate the effects of marihuana smoking on exercise performance, 12 healthy young subjects did progressive exercise testing on an ergocycle to exhaustion under two conditions: non-smoking (control) and 10 min after smoking a marihuana cigarette (containing 1.7% of delta-9-tetra-hydro-cannabinol) of 7 mg X kg-1 body weight. Heart rate, arterial blood pressure, minute ventilation (VE), breathing rate (fb), oxygen uptake (VO2), and carbon dioxide output (VCO2) were measured before, during, and for 4 min after the exercise. Tidal volume was calculated from VE X fb-1. The exercise duration was also measured. Forced expiratory volume (FEV1) was measured: before smoking (rest); before exercise (10 min after smoking); and after exercise. Carboxyhemoglobin levels were measured before and 10 min after smoking in four subjects. Marihuana smoking reduced exercise duration (16.1 +/- 4.0 to 15.1 +/- 3.3 min, P less than 0.05). At peak exercise performance, there were no differences in VO2, VCO2, heart rate, and VE between the two experimental conditions. Marihuana induced tachycardia at preexercise (94.3 +/- 13.3 beats X min-1 to 119.0 +/- 18.0, P less than 0.01) that was sustained up to 80% of maximum effort and during the recovery period. After marihuana, VE, VO2 and VCO2 were increased above control from 50% of maximum effort to the end of the test. Marihuana induced a bronchodilation (FEV1 from 4.28 +/- 1.00 to 4.43 +/- 1.031, P less than 0.0) that was still present after exercise. Exercise induced a bronchodilation in the control condition but not in the marihuana smoking condition.

Source: Acute Effects of Marihuana Smoking on Maximal Exercise Performance. - Medical Journals - Healia
 
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