As with most things in life, too much of a good thing can really be bad for you. It looks like this principle may also apply to too much jogging, according to researchers out of Denmark.

Dr. Schnohr and colleagues put together a fairly impressive study that analyzed 5,048 healthy individuals who were a part of the Copenhagen City Heart Study. Of these, 1,098 were joggers and 3,950 were sedentary non-joggers. For 12 years, the frequency and pace of these 1,098 joggers were tracked. The point of the study was to determine how much jogging will result in decreased mortality, and if too much jogging can be harmful.

Results

  • Jogging for more than 1-2.4 hours per week resulted in the lowest mortality.
  • Jogging only 2-3 days per weeks resulted in the lowest mortality.
  • Those who jogged at a slow or moderate pace also had the lowest mortality rates.

Strenuous joggers (those who jogged for more than 2.4 hours per week, more than 3 days per week and at a fast pace) had the same rate of mortality than those who did not jog at all!

…maximal cardiovascular longevity benefits were noted with moderate doses of running (specifically 6 to 12 miles per week), running durations of approximately 50 to 120 min per week, a running frequency of approximately 3 times per week, and a modest pace of approximately 6 to 7 miles per hour. – Journal of the American College of Cardiology

Further studies cited in this article report that the safe upper limit for running is about 30 miles per week, 46 miles of walking per week for cardiovascular health and longevity.

It is hypothesized that too much strenuous jogging or physical activity changes the heart’s architecture, which can lead to arrhythmia, poor heart pumping function and scar tissue formation around the heart.

Take Home Point

While this is an observational study (instead of a more convincing randomized controlled trial), the study population is large and was followed for a 12-year period, which improves the strength of the study.

This study adds to the pool of knowledge that again, too much of a good thing can be bad for you. Jogging is a healthy activity if performed in moderation (3 days per week at a slow to moderate pace for no more than 30 miles per week). Strenuous jogging or jogging for many hours or miles per week may be detrimental to heart health.

Keep in mind that this study does not address high-intensity interval training, which allows strenuous activity but for shorter, interval periods of time. High-intensity interval training has also been shown in various studies to be a safe practice form improving health.

Dose of jogging and long-term mortality: the Copenhagen City Heart Study, Peter Schnohr, et al., J Am Coll Cardiol, doi:10.1016/j.jacc.2014.11.023, published February 2015, abstract.