How much is too much? That is not always a question that we ask ourselves when it comes to exercise. However, recent research made international headlines when it suggested that jogging too much is just as bad for your health as being inactive. This novel study supports prior research linking excessive exercise with health issues. However, what is substantial about the new report in the Journal of the American College of Cardiology is that the investigators were able to identify an “ideal time range” and an “ideal speed” for jogging to improve health.
Over a 12 year period, 5,048 healthy individuals were tracked and instructed to report their total hours of jogging, their jogging frequency, and their personal perception of pace. At the completion of the study, it was found that joggers that performed strenuous exercise where just as likely to die as sedentary individuals (non-joggers). Furthermore, jogging from 1 to 2.4 hours per week at 5mph was found to be optimal for health. The relationship between jogging level and mortality can be described as a U-shaped curve; representing the fact that there is an ideal balance between not exercising and exercising in excess.
The mechanism behind increased mortality and excessive strenuous exercise originates in the physiology of the cardio-pulmonary system. Over the span of decades, stress on the heart brought on by exercise can slowly accumulate, potentially resulting in heart arrhythmias or localized structural failures.
This U-shaped curve closely reflects the general relationship between distress (or negative stress) and eustress (or positive stress) and health outcomes. However, when interpreting this data it should be considered that the sample size was relatively small, with only 36 participants being classified as strenuous joggers; of whom only 2 died within the 12 years. The small sample size illustrates that further research is necessary to clarify the ideal range of exercise (specifically jogging). Also, a prior study with the same research group (2006) found that individuals who are active during their leisure time have a lower mortality rate than those who are sedentary. While there certainly is an upper limit to exercise, having a generally active life style has consistently shown to be beneficial for disease prevention and longevity.