Exercise Slows Aging — Here’s How
Exercise — especially high-intensity interval training — helps your cellular mitochondria fight off aging.
“Perchance he for whom this bell tolls may be so ill, as that he knows not it tolls for him; and perchance I may think myself so much better than I am, as that they who are about me, and see my state, may have caused it to toll for me, and I know not that.”
John Donne (1572–1631) wrote those lines in Devotions Upon Emergent Occasions, Meditation XVII. The words’ meaning is debated but reminds me that the clock ticks for all of us, and we change as it does.
Aging: Heart weakening, blood vessel thickening, and more
Many changes associated with aging begin in our 20s. For example, the maximum heart rate for a man in his late 20s declines by approximately one beat per minute, per year. The heart’s ability to pump blood diminishes too, with a drop of 5 to 10 percent each decade. I am not surprised that our aerobic capacity declines; we may become more tired and out of breath with even modest physical activity.
Part of our decline is because our blood vessels stiffen with time, with associated blood pressure increases. Worse yet, the blood thickens, rendering it more challenging to push it throughout our bodies. Add into this a decline in the oxygen-carrying red blood cells, and we have a problem.
Most of us begin to gain weight, with muscle loss, often beginning in by our 40s. Eventually, the muscle can decrease by upwards of 50 percent, which contributes to weakness and disability. Both men and women lose calcium with age, leading to a risk of thin bones (osteoporosis), especially among women.
The extra weight is often due to increases in our body fat. There can be resultant increases in so-called bad LDL cholesterol and a drop in good HDL cholesterol. Blood sugar levels rise, significantly lifting our risk for type 2 diabetes.
Slowing the aging clock
Let’s look at how exercise can affect your cells’ internal components to enhance your health. I say it often: Physical activity helps to keep you healthy. You know about the psychological benefits and how exercise can help you sleep better, maintain muscle tone, drop your cancer risk, and extend your healthy lifespan. Today I want to focus on an essential mechanism of action. We’ll look at how exercise can cause your cells to make more proteins to feed your cell’s mitochondria or power stations.
Researchers examine the molecular makeup of muscle cells
Scientists enrolled 36 men and 36 women from two age groups. They included so-called young volunteers, ages 18 to 30, and “older” volunteers, 65 to 80. Researchers divided the subjects into three different exercise programs:
- high-intensity interval biking
- strength training with weights
- a combination of strength and interval training
The researchers then removed tissue from the study volunteers’ thigh muscles, comparing the three exercise program group members’ molecular makeup. Here are the study results:
- Strength training: Effective at building muscle mass
- High-intensity interval training: Greatest benefits at the cellular level.
Exercise — and in particular, high-intensity interval training in aerobic activities such as biking and walking — resulted in cells producing more proteins for the cellular powerhouses, mitochondria. Physical activity slowed aging at the cellular level. I want to examine this with you in more detail.
Improvements at the cellular level
First, high-intensity interval training led to the most significant benefits identified at the cellular level. For example, the interval training group’s younger volunteers experienced a 49 percent increase in their mitochondria’s capacity, while the older subjects had an extraordinary 69 percent increase.
Let’s explore this remarkable finding a bit more. Our mitochondria are membrane-bound organelles in our cells. They are our cells’ powerhouses: The majority of the chemical energy powering our cells’ biochemical reactions is created within the mitochondria. Our cells store this energy in a small molecule known as ATP, or adenosine triphosphate.
But wait, there’s more. The interval training also led to improvements in the insulin sensitivity of the study participants. This improvement in insulin sensitivity should translate into a lower probability of the development of diabetes. But those of you who do strength training should not despair; the study subjects in that group experienced improved muscle strength. This improvement in power is essential, given we typically experience declines in our muscle with age.
In summary, we now have some clues about how exercise works at the molecular level to improve our health. You may wish to consider combining high-intensity interval training combined with periodic strength training. The study reminds us, however, that any exercise is better than doing none. Physical activity can encourage your cells to create more RNA copies of genes that code for mitochondrial proteins. Increase your muscle protein amount through activities such as high-intensity biking. You may reverse age-related declines in your cell powerhouses, the mitochondria.
Muscles are somewhat unusual, given the cells do not divide frequently. Therefore, it is not surprising that muscle cells can accumulate a lot of damage. I love that exercise can decrease the deterioration of mitochondria and ribosomes. In the future, I expect that we find physical activity to be associated with enhanced intracellular organelle function in non-muscle tissues. As we better understand how exercise affects cellular pathways related to aging, we may someday target these to slow aging down.
Thank you for joining me today. I’m Dr. Michael Hunter.
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Mitochondria image courtesy of: