Key result
Smoking marihuana increases resting HR by ~34% versus control without affecting BP or oxygen uptake.
Why the study?
The effects of smoking marihuana on cardiorespiratory responses during submaximal exercise were not well characterized.
Does smoking marihuana alter cardiorespiratory responses during submaximal exercise in chronic male users?
RCT (n=6)
Double-blind
counterbalanced
Does smoking marihuana alter cardiorespiratory responses during submaximal exercise in chronic male users?
Smoking marijuana significantly increases heart rate and myocardial oxygen demand (HR x SBP) during submaximal exercise and recovery in chronic users without affecting ventilation or oxygen uptake.
Marijuana-induced heart rate rises may heighten ischemia risk; extends RCT evidence on acute effects during exercise and recovery.
Six male chronic marihuana (MH) users exercised on a bicycle ergometer for 15 min at approximately 50% VO2max under 3 conditions: (1) not smoking (control), (2) after smoking MH containing 7.5 mg (-) delta-9-tetrahydrocannabinol, and (3) after smoking placebo marihuana (PL). The MH was administered double-blind in a counterbalanced repeated-measures design. Heart rates (HRs), arterial blood pressures (BPs), pulmonary ventilation (VE), and oxygen uptake (VO2) were measured during exercise and 15 min recovery. PL had no effect on any of the physiologic variables. Smoking MH had no effect on systolic blood pressure (SBP), diastolic blood pressure (DBP), VE, or VO2, but did induce a marked increase in heart rate which persisted throughout exercise and recovery periods, averaging 34% higher than control values at rest, 18% higher during exercise, and up to 50% higher during recovery. MH smoking increased the product of HR x SBP in all circumstances.
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Avakian et al. (1979) conducted an RCT in chronic marihuana users (n=6). Marihuana vs. Not smoking (control) and placebo marihuana was evaluated on Heart rates, arterial blood pressures, pulmonary ventilation, and oxygen uptake. Smoking marihuana increased heart rate by 34% at rest, 18% during exercise, and up to 50% during recovery compared to control, with no effect on blood pressure or oxygen uptake.
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