Limited evidence suggests that a person’s risk of heart attack during the first hour after smoking marijuana is nearly five times his or her usual risk. 73 This observation could be partly explained by marijuana raising blood pressure (in some cases) and heart rate and reducing the blood’s capacity to carry oxygen. 74 Marijuana may also cause orthostatic hypotension (head rush or dizziness on standing up), possibly raising danger from fainting and falls. Tolerance to some cardiovascular effects often develops with repeated exposure. 75 These health effects need to be examined more closely, particularly given the increasing use of "medical marijuana" by people with health issues and older adults who may have increased baseline vulnerability due to age-related cardiovascular risk factors (see " Is marijuana safe and effective as medicine? ").
Physical exercise has established efficacy as an antidepressant in individuals with depression and current medical evidence supports the use of exercise as both a preventive measure against and an adjunct therapy with antidepressant medication for depressive disorders.      A July 2016 meta-analysis concluded that physical exercise improves overall quality of life in individuals with depression relative to controls.  One systematic review noted that yoga may be effective in alleviating symptoms of prenatal depression .  The biomolecular basis for exercise-induced antidepressant effects is believed to be a result of increased neurotrophic factor signaling, particularly brain-derived neurotrophic factor .