by Aimee Keenan-Greene
Researchers have studied evidence that suggests physical and sexual activity might trigger heart attacks or myocardial infarction for the occasional exerciser.
The new information in the Journal of the American Medical Association says, for those who aren't couch potatoes and get regular cardio workouts, the association between physical or sexual activity and myocardial infarction (MI) or sudden cardiac death (SCD) was less.
Scientists identified 10 studies investigating episodic physical activity, 3 studies investigating sexual activity, and 1 study investigating both exposures.
The outcomes of interest were:
MI (10 studies), acute coronary syndrome (1 study), and SCD (3 studies). Episodic physical and sexual activity were associated with an increase in the risk of MI (RR = 3.45; 95 percent confidence interval [CI], 2.33-5.13, and RR = 2.70; 95 percent CI, 1.48-4.91, respectively).
Episodic physical activity was associated with SCD (RR = 4.98; 95 percent CI, 1.47-16.91). The effect of triggers on the absolute rate of events was limited because exposure to physical and sexual activity is infrequent and their effect is transient; the absolute risk increase associated with 1 hour of additional physical or sexual activity per week was estimated as 2 to 3 per 10 000 person-years for MI and 1 per 10 000 person-years for SCD.
Habitual activity levels significantly affected the association of episodic physical activity and MI (P < .001), episodic physical activity and SCD (P < .001), and sexual activity and MI (P = .04); in all cases, individuals with lower habitual activity levels had an increased RR for the triggering effect. For every additional time per week an individual was habitually exposed to physical activity, the RR for MI decreased by approximately 45 percent, and the RR for SCD decreased by 30 percent.
Scientists extracted descriptive and quantitative information from MEDLINE and EMBASE (through February 2, 2011) and Web of Science (through October 6, 2010) and calculated summary relative risks (RRs) using random-effects meta-analysis and absolute event rates based on US data for the incidence of MI and SCD.
Using the Fisher P value synthesis method to test whether habitual physical activity levels modify the triggering effect and meta-regression to quantify the interaction between habitual levels of physical activity and the triggering effect.