Intensity Matters

As recently as the 1970s, complete bed rest was recommended after a cardiovascular event. This changed after the 1966 Dallas Bed Rest and Training Study. This study showed just how detrimental inactivity is for heart health.

In the Dallas study, researchers took 5 healthy, 20-year-old men and put them on bed rest for three weeks. They were not allowed to even stand up to go to the bathroom, which was typical for treatment after a heart attack. It was thought to be too stressful. The three weeks of inactivity was followed with 8 weeks of intense training.

One interesting and unexpected thing happened during the study. While three of the men were typical students, two were athletes, one was a football player and one was a endurance runner. The athletes declined faster and took longer to recover from bed rest. There is much speculation about this finding, but it has never been repeated for the following reasons.

In 3 weeks of very strict bed rest the men showed a dramatic drop of 26% to 27% in maximal oxygen uptake ( VO₂ max) and a 31% drop in maximal stroke volume, the amount of blood the heart pumps during exercise. In only took three weeks of inactivity to mirror the aerobic decline equivalent to 30 to 40 years of normal ageing.

In fact, in a follow up study, thirty years later, the same men, showed that three weeks of bed rest had a greater impact on their physical capacity when compared with 30 years of aging. They also found that after completing another six month endurance exercise program thirty years later, they completely reversed the age-related decline in aerobic power. They weren’t able to return to their youthful VO₂ Max, however the improved aerobic power after the training program was a result of peripheral adaptation. In other words they were better able to deliver oxygen to their working muscles after training.

Being sedentary is a health risk.

A recent review published in the Canadian Journal of Cardiology proved that bed rest can age the heart by decades in a matter of days or weeks. Researchers Carmelo Mastrandrea, and co-author Richard Hughson at the Schlegel-UW Research Institute for Aging (RIA), were the first to review and analyze data across 38 studies comparing bed rest effects to natural ageing.

What did they find?

A rapid decline in heart health. Including significant reductions in cardiovascular function as well as a decrease in heart size, by up to 5% happens in a short time, between 7-10 days. This occurs almost immediately during a period of inactivity.

This is another good reminder that exercise is an important component of ageing well. Exercise should not be viewed as something to “fit in” but more of an essential habit for preventing disease and maintaining health.

Staying active, even with small movements, physical therapy and daily exercise snacks can prevent these severe cardiac changes.

There is good news.

Sports cardiologist, Dr. Benjamin Levine wanted to know if we can reverse the age related stiffening of our heart muscle which occurs somewhere in our 50s (unless we are sedentary and then it occurs much earlier.)

Levine says,

Think of the heart muscle as a rubber band. In the beginning, the rubber band is flexible and pliable. But put it in a drawer for 20 years and it will emerge dry and brittle.

Levine recruited 61 healthy, but sedentary, participants. 48% were men and 52% were women, between 45-64 years old to participate in a two year exercise program. One group was assigned to balance training, yoga and weight training three times a week. The other group did high-intensity exercise training four or MORE days a week.

Activity or Exercise. It is not one or the other; it’s both.

Intensity matters even as we age.

There are a lot of myths and misconceptions about ageing and one that just won’t go away is that we should focus on “moderate” activity. That walking, yoga, mobility exercises are fine. They are fine, if that is what you are capable of, but if you can do more, you should include that too.

In Dr. Levine’s study they found that the group doing high intensity interval training reversed heart aging. He states,

“We took these 50-year-old hearts and turned the clock back to 30- or 35-year-old hearts.

The participants doing intervals were able to use oxygen more efficiently and their hearts were less stiff after training.

The intervals followed the 4×4 interval program, a Norwegian cross country ski workout, which is four minutes at 95 percent of your maximal ability, followed by three minutes of active recovery, repeated four times.

It is high intensity training.

Does intensity matter?

Think you are too old for intervals?

Maybe not. The Generation 100 study also found that intervals are important. They followed 1500 adults, all in their 70s, for five years to find out if exercise results in a longer and healthier life as well as the differences between moderate and high-intensity training.

No surprises, performing high-intensity interval training for five years increases quality of life and improves cardiorespiratory fitness more than moderate intensity exercise.

The Fine Print.

There are a few important details to remember with all these studies.

First, is that moving is a critical component of healthy ageing and even as you get older you should try to do some type of intense exercise.

Second, intensity is personal, what is hard for you may not be difficult for someone else, don’t compare yourself to others. Remember to exercise within your own capabilities, but don’t think that just because you are getting older you should take it easy.

Finally, studies are not real life. A comprehensive exercise routine should include all the elements of fitness, not only intensity, but endurance, strength, power and moderate exercise. Every workout should not be done at the same intensity, variety matters too.

Change your mind, change your health,

Shayla

Have questions about your exercise routine? Book a call with me and we can discuss if you are getting the most from your routine.