Health

As little as 15 minutes of exercise helps. Today we look at how much you should do to optimize your heart health.

Michael Hunter MD

Oct 7, 2020·7 min read

“If I’d known I was going to live this long, I’d have taken better care of myself.” So opined Eubie Blake, a pianist, and composer of jazz and ragtime, who lived from 1887 to 1983.

You know that exercise is right for you. Even minimal physical activity can advance your health and sense of well-being. I am a strong advocate of incorporating walking into a physical activity program, but a thoughtful reader recently led me to think about how much aerobic activity we need to do to optimize cardiovascular health.

Today we begin with a review of some optimal lab numbers before turning to physical activity benefits, from walking to running. More specifically, I will focus on optimal levels of exercise for a healthy heart.

So, you want to get your heart in tip-top shape. You may immediately think about physical activity, the subject of our discussion today. First, here are some other keys to good heart health.

The numbers

Let’s start with some numbers, including the big three:

• Blood pressure. The normal is 119/79 or below. Pre-high blood pressure is 120 to 139 systolic pressure (the top number on your blood pressure measurement) and 80 to 89 diastolic pressure (the second number).
• Fasting blood sugar. As measured after you don’t eat or drink anything except water for at least 12 hours, your fasting blood sugar can indicate type 2 diabetes. A normal blood sugar level is 100 or less. A blood sugar of 101 to 125 indicates “pre-diabetes.” Finally, a fasting blood sugar of 126 or more indicates diabetes.
• Cholesterol. If your so-called bad cholesterol is too high, you have a higher risk of having a heart event, such as a heart attack. On the other hand, having elevated levels of good cholesterol is protective. Here’s how these numbers play out: Desirable levels for adults include total cholesterol of under 200. A bad (LDL) cholesterol level should be under 100, while good (HDL) cholesterol should be at least 60. Finally, triglycerides should be under 150.

Watch your waistline

I initially wanted to write that you should optimize your weight. I prefer to say that while being obese or overweight makes heart disease more likely, we should look beyond the number on your scale. I mean that where you carry your weight matters: Excessive fat in your belly area can be particularly troublesome. Here is what you should consider, besides checking your weight — measure your waist circumference with a tape measure.

We men should aim for a waist of under 40 inches. Our female counterparts have a lower risk of heart disease and type 2 diabetes when their waist size is under 35 inches, at least as compared to women with larger waistlines. If you are above these sizes, don’t get too hung up on the numbers. Instead, check-in with a valued health professional and learn the best steps to improve your health.

Don’t smoke tobacco

In terms of habits, don’t smoke. Tobacco smoke injures your heart. It can raise your blood pressure (please see above) and increase blood clots’ probability. These tiny clots can lead to a stroke or a heart attack. In addition to not smoking, I try to avoid being around tobacco smoke.

Lower your stress levels

Stress can harm you indirectly or directly. For example, if you are stressed, you may smoke or drink more. You may sleep less or take less time out for physical activity. Concerning direct harm, stress can raise your body’s levels of stress hormones. Stress can increase your blood pressure and may even affect how your body forms clots. Here are five keys to reduce your level of stress and to help your heart:

• Meditate. Deep breathing and inward-focused thought can lower blood pressure and reduce your risk of heart disease. You can do it, and even a few minutes of sitting quietly, with your eyes closed and focusing on your breathing, can help. Others relax the mind through yoga or prayer.
• Take a break. Cut those cords. Try to reduce your exposure to emails, television news, and social media.
• Stay positive. You may want to try to see the positive side of things. Even laughter can lower stress hormones, increase in so-called good HDL cholesterol, and reduce blood vessel inflammation.
• Do your thing. Find some “you” time. Private time may mean listening to music, reading a book, or getting a massage. For me, it is playing classical music on my piano.
• Exercise. You may lower your blood pressure, make your heart muscle more robust, and better handle the weight.

I want to address the last key element in more detail. What does current research say about the health effects of light exercise? And about vigorous physical activity? I’ll start with my conclusions and work backward.

• Moderate activity (such as an hour of walking or gardening weekly) is associated with a lower chance of experiencing a stroke, myocardial infarction (heart attack), or death from all causes. These conclusions are the product of an analysis of 22 studies, including over 300,000 adults.
• Still, while more exercise may provide additional health benefits, physical activity upsides appear to plateau after 45 to 60 minutes of moderate daily exercise.

The renowned epidemiologist Jeremy Morris, working in the United Kingdon, analyzed postal and transport workers and civil servants. Ralph Paffenbarger, a fellow legend in the United States field, examined college alumni and longshoremen. These historic studies reported in the 1970s and 1980s:

Regular exercise was associated with a markedly reduced probability of heart attack and cardiovascular death, in addition to a lower all-cause mortality rate.

On a personal note, Morris regularly walked from early in life to just before death. He lived until 99 years of age. Paffenbarger began later, leaving his sedentary life behind at age 45. He then demonstrated what is possible, finishing 151 marathons and ultramarathon. He did five challenging Western States 100-Mile Endurance Runs. He retired from running at age 71, having developed severe heart disease that required quadruple bypass heart surgery. He died 13 years later.

You may wonder if Paffenbarger’s high-intensity exercise may have contributed to heart damage. He did considerable research suggesting that it did not. Still, his research hinted that physical activity’s many positive health benefits might plateau at relatively moderate exercise levels.

Can you do too much exercise?

Paffenbarger’s many contributions did not raise concern that high-intensity exercise might produce cardiac damage. Still, his work did suggest that the health benefits of exercise plateau at moderate levels of physical activity.

The Paffenbarger-led 1978 study of nearly 17,000 male Harvard graduates looked at heart attack (myocardial infarction) and total weekly energy expenditure in kilocalories (kcal).

Heart attack risk dropped progressively up to an exercise level of about 2,000 to 3,000 kcal per week (about 10,000 steps, as I recall). After that, the health benefits appeared to plateau.

• Participation in vigorous sports increased health benefits, moderately.

But,

• Beyond the three- to five-times the minimal activity level, there did not appear to be any additional survival benefits. It seems reassuring that there did not appear to be any downsides, even ten times more than the recommended minimum.

I’ll end with some definitions, as assessments of exercise intensity levels can be remarkably subjective. What do I mean by light-to-moderate intensity? An example is walking purposefully (as if you have somewhere to go). Your breathing may be more noticeable, but you can still speak in full sentences.

Are you aiming for a moderate intensity effort? Brisk walking lands you in this category. You walk with moderate effort, breathing harder. Still, you can talk in full sentences but need to take more breaths.

Let me end with a reminder that you do not have to be a world-class athlete to get health benefits from physical activity. While you should do aerobic training to perform endurance sports or optimize aerobic fitness, you can drop your disease risk without lifting your heart rate into the aerobic zone.

You are not required to sustain intense efforts for prolonged periods. Based on the analysis of 22 studies cited above, modest activity is associated with significant benefits similar to the health benefits linked to aerobic fitness.

We end with a nod to the Nike slogan: Do it. Don’t have enough time. Just do it. I sneak in a few short (as little as ten minutes) walks each day, between patients. Yes, an excellent daily goal can be 30 minutes, but three episodes of ten minutes get the job done. The best form of exercise? The one that you will do.

Thank you for joining me today. I look forward to examining the benefits of more vigorous activity in a later post.

References