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Elder Health

Do the Benefits You Get from Aerobic Exercise Change as You Age?

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When you’re young, you exercise to lose weight and to look better in a swimsuit. Thoughts of preventing disease are a distant thought. After all, you’re going to live forever, right?

But as you age, the focus shifts more towards exercising for health and to stay fit and functional as you approach your retirement years. You start thinking more about your diet more too. You hear so much about the benefits of eating fruits and vegetables with their natural antioxidants, but, surprisingly, exercise offers antioxidant benefits as well.

Exercise as an Antioxidant

Is exercise an antioxidant? In a sense it is. When you work out, the stress you place on your body creates a flood of cell-damaging free radicals. In response, your body ramps up its own internal antioxidant defense system to fight those rogue molecules.

Yes, you really do have an internal antioxidant defense system. It’s made up of enzymes and other protein components, primarily in your lungs and liver. These enzymes are also called into action when you expose your body to free-radical producing toxins, from the food you eat to the air you breathe. You also get antioxidants by eating a healthy diet. Two of the major sources of dietary antioxidants are vitamins C and E. These vitamins act as a team to vanquish free radicals.

Interestingly, one reason you get positive health and fitness benefits from aerobic exercise is related to the free radicals exercise creates. You probably think of free radicals as being “bad.” They are – but they’re beneficial, in moderation, at least within the context of exercise.

In response to aerobic training, genes are turned on that tell cells to build new mitochondria through a process called mitochondrial biogenesis. It’s free radicals that turn on the genes that do this. Mitochondrial biogenesis is a good thing since more mitochondria means greater potential for ATP production. When you have more energy-producing mitochondria, you can make more ATP to sustain exercise longer and, therefore, have greater endurance.

Supporting this idea that free radicals aid in exercise adaptations are studies showing that taking supplemental antioxidants blocks mitochondrial biogenesis. Antioxidant supplements blunt the body’s internal antioxidant response and, in turn, the stimulus to build new mitochondria.

Now you see why you don’t want to swallow a handful of antioxidant supplements before a workout. Doing so could interfere with the endurance benefits you get from aerobic training. In studies that show this, they used vitamins C and E, both antioxidant vitamins. In supplemental form, these antioxidants seem to interfere with cellular adaptations to aerobic exercise.

Effects of Aging on the Internal Antioxidant Defense System

How is this relevant to aging? According to the results of a new study, older people have a reduced antioxidant response to exercise. In other words, as you age, your body’s natural antioxidant defense system that turns on in response to exercise becomes less robust. Without the antioxidant defense system revving up, you may not get the same increase in cellular mitochondria and improvements in exercise endurance.

In the study, researchers asked a group of healthy men between the ages of 18 and 30 and another group of healthy men over the age of 55 to do 30 minutes of moderate-intensity cycling at 70% of their V02 max. Before and after exercise, they measured, via blood tests, a variety of parameters to look at their antioxidant response to the workout.

What they found was that the older men had a blunted antioxidant response to exercise compared to the younger guys. Since this response plays a key role in how the body adapts to aerobic exercise, you might expect that younger adults get greater cellular adaptations (mitochondrial biogenesis) to aerobic exercise than older people.

In the study, they identified a particular pathway that involves a regulator protein called Nrf2 that’s impaired in older people. The weakness in this pathway may explain why older adults don’t get the same adaptations to moderate-intensity aerobic exercise as younger adults.

Exercise is Still Important for All Age Groups

These results don’t mean that you won’t get benefits from aerobic exercise once you’re past a certain age. It suggests that relatively short periods of moderate-intensity exercise don’t lead to the same cellular adaptations in older people as you see in younger people. Remember, this is only one study and the data came from a single exercise session, so it’s difficult to draw firm conclusions.

It’s possible that older adults may need to exercise at a higher intensity to get the same cellular adaptations as younger people. They may also need more than 30 minutes of exercise to get the same benefits. In this study, the participants were exercising at a 70% of their aerobic capacity, a moderate pace for 30 minutes. What if they had exercised at a high intensity – HITT training style? What if they had worked out longer? A lot of questions are still unanswered.

Is HIIT Training Better?

HIIT training may be just what the doctor ordered for healthy, older adults. The muscle fibers you lose most quickly as you age are fast-twitch muscle fibers. Moderate-intensity cardio mainly works slow-twitch fibers while high-intensity exercise brings more fast-twitch muscle fibers into the mix. That’s what older adults need.

Even if older adults don’t develop the same degree of mitochondrial adaptations, aerobic exercise still offers tons of health benefits. Research shows that people, of all ages, who exercise have a longevity advantage as well as a lower risk for a number of health problems, including heart disease, type 2 diabetes, and even some forms of cancer.

Just as important, if not more so, is resistance training. Working muscles against resistance is the best way to hit those fast-twitch muscle fibers that you lose with age. A combination of both forms of exercise is the best prescription for healthy aging.

 

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