Eric Hopton for redOrbit.com – Your Universe Online
For those of us who take their exercise with caution, this may come as something of a vindication. When it comes to physical action, we at redOrbit think a riveting round of ping pong is enough exercise for the day.
Don’t get us wrong – keeping fit is a great thing and, in moderation, leads to better average longevity and general health. As this study from Denmark points out, people who are physically active had at least a 30% lower risk of death during follow-up compared with those who are inactive.
Too much of a good thing
The conclusions of the study were simple. There was a definite association between all-cause mortality and the “dose” of jogging undertaken. “Dose” was calibrated by pace, quantity, and frequency of jogging. Light and moderate joggers were found to have lower mortality than sedentary non-joggers. But, and here’s the catch, those strenuous super-joggers had a mortality rate “not statistically different from that of the sedentary group.”
The research was part of the Copenhagen City Heart Study and the results have been published in the Journal of the American College of Cardiology. The study has been following 1,098 healthy joggers and 3,950 healthy non-joggers since 2001.
It was the “moderate” joggers who came out best. The team behind the study found that, compared with sedentary non-joggers, 1 to 2.4 hours of jogging each week was associated with the lowest mortality rate and that the optimal frequency of jogging was 2 to 3 times per week. The optimal pace was slow – around 5 miles an hour. The joggers were divided into light, moderate, and strenuous joggers. The lowest “Hazard Ratio” (HR) for mortality was found in light joggers, followed by moderate joggers, then strenuous joggers. The participants who ran for more than four hours a week or did no exercise at all had the highest death rates.
So, if the findings of this work are replicated elsewhere, it may be that there is after all an upper limit for safe exercise. The conclusion was that, “when prescribing exercise to improve longevity, strenuous exercise is not necessary, and might reduce the health benefits of light to moderate physical activity.” The scientists stress that further studies are needed “to explore the mechanisms by which excessively strenuous exercise adversely affects longevity before the pattern of association between exercise intensity and long-term mortality can be incorporated into physical activity recommendations for the general public.”
While the mechanism behind this fall-off of benefit from more strenuous exercise is not yet understood, the authors suspect that changes to the heart and arteries during the stress of exertion may be at least part of the answer.
It looks like the widely accepted recommendation that we all have 150 minutes of moderate-intensity activity a week is spot on. It’s not exactly a hare and tortoise situation, but it might just make the brisk walker or the plodding jogger feel better when the next racing runner flies past them.
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