Is Early Morning Exercise Bad For You?

Hi Doug –

I watched a BBC Horizon documentary recently (no, not the Fast diet) about the human body clock. One aspect of this they talked about was the best time of the day to exercise (as I recall this was mostly in reference to “cardio” exercise.) Something that interested and worried me was the claim that cardio in the morning not only had no benefit on blood pressure but was also dangerous. Your blood pressure is naturally higher in the morning and putting more pressure on the heart at this time is asking for a heart attack. I usually prefer to run in the mornings and now that I live in Houston, if I want to run outdoors, the morning is the only sensible option. I’d be interested in your opinion on this subject.

Thanks,
Des

Great question Des – thanks for sending it in.

Are millions of people putting themselves at risk as they get up early, slip on their running shoes and head out for a morning run? Could they be courting a heart attack or stroke?

This idea – that early morning exercise is potentially hazardous to your health – has been a controversial topic in the world of fitness for a number of years.

The supporters of avoiding early morning exercise point out that your stress hormones begin to rise as morning approaches (cortisol, adrenaline) and your heart works a little harder bringing your hear rate up. And that your blood vessels narrow causing your blood pressure to rise.

You’re waking up. It’s normal. It doesn’t mean you shouldn’t exercise.

What everyone seems to be forgetting is that the studies that are casually mentioned in articles online – “research shows” without any references – are very clear about who is at risk.

If you have cardiac risk factors – high blood pressure, diabetes, overweight / obese, smoke, are generally inactive, have an unhealthy diet and unmanageable stress – then yes, you should be careful with high levels of exertion in the morning.

But, if you’ve been exercising or running for years, have a healthy diet, are not overweight, don’t smoke, and have normal blood pressure, then there’s no reason to think that an early morning run is going to cause you heart trouble.

“In fact, it’s more dangerous to skip exercise out of fear than to schedule the workouts before 8 a.m.,” according to Dr. Deepak L. Bhatt, director of the Interventional Cardiology Fellowship at The Cleveland Clinic.

And to further support the idea that running or exercising in the morning isn’t bad for you, there’s this study on the effect of time of day has on your blood pressure.

Running as your only form of fitness is, however, not without its drawbacks. It depends on how far you run and how hard or fast. Running distances of “about 1 to 20 miles per week, speeds of 6 to 7 miles per hour, and frequencies of 2 to 5 days per week are associated with lower all-cause mortality, whereas higher mileage, faster paces, and more frequent runs are not associated with better survival” (from a review of the effects of endurance training on the heart by the Mayo Clinic and American College of Sports Medicine).