A new study in the journal HEART finds increased risk of cardiovascular events among inactive patients. No surprise there. But this study, the second one to come out recently with similar findings, also finds an increased risk of death among patients who participated in daily, "strenuous" activity.
Lead author Ute Mons of the German Cancer Research Center writes that "Both inactive and daily-active patients had increased hazards of mortality compared with the reference group of patients who were active two to four times per week, but with the hazards being highest in the inactive-patient group." (emphasis ours)
Every study has some inherent problems and this one is no different. Although the authors adjusted their data to account for both pre existing "co-morbid conditions and for self-reported poor health", they note that "Because patients with poorer health are less likely to engage in strenuous physical activity, reverse causation bias could have led to an overestimation of the hazards in the inactive patient group and to an underestimation in the most physically active." (emphasis ours. )
For now it appears that while inactive patients are still at the highest risk, patients who exercise more than 2-4 times weekly also appear to be at substantially increased risk of death from both cardiovascular events and "all cause" mortality. Doctors take heed...more isn't necessarily better.
Reference: Mons Y, Hahmann H, Brenner H. A reverse J-shaped association of leisure time physical activity with prognosis in patients with stable coronary heart disease: evidence from a large cohort with repeated measurements. Heart 2014; DOI:10.1136/heartjnl-2013-305242.