Your high school biology teacher probably taught you this one fact – but chances are, you haven't thought about it much since then...
Mitochondria are the "powerhouses" of the cell.
That old biology lesson becomes much more important as you age...
That's because the health of these microscopic power plants pretty much dictates whether your golden years are filled with energy and vitality... or fatigue and disease.
When your mitochondria start to sputter, your whole body slows down.
To understand why they're so crucial to healthy aging, let's peek at what they actually do...
These tiny, bean-shaped structures turn the food you eat and the oxygen you breathe into adenosine triphosphate ("ATP"). ATP is the fuel your cells use to contract muscles, pump your heart, fire nerves, and repair tissue.
Here's what one mitochondrion looks like...
Along with generating energy, mitochondria perform other key bodily processes like making heme (a compound that transports oxygen via red blood cells), regulating and releasing calcium ions needed for muscle contraction, helping with blood clotting, aiding in cell signaling (like getting cells to divide or grow and even telling old and damaged cells to self-destruct), and adapting to stress.
The number of mitochondria per cell depends on what kind of cell it is and its energy requirement. For example, the cells in our muscles and nervous system are chock-full of mitochondria.
But mitochondria can become less efficient as we age. They might produce less energy and struggle to remove damaged parts. That decline is tied to many health problems common in old age, like diabetes, cardiovascular disease, cancer, Alzheimer's disease... you name it.
Now, while there's no way to keep existing mitochondria from aging, your body has a workaround.
How to Fight Mitochondrial Aging
Surprise, surprise... It's exercise.
Aerobic exercise is known to boost mitochondrial health. And so does strength training...
In a 2020 study, researchers recruited 16 adults aged 59 on average. The participants completed a full-body strength-training program, twice weekly, for 10 weeks.
The researchers took small samples of thigh muscle before the program, after the first workout, and after the last week of training. While one workout only produced a short-term, small response, they found that after 10 weeks, the muscles looked a whole lot different.
Protein levels in all five sections of the mitochondrial electron-transport chain rose between 39% and 180%. This chain is sort of like an assembly line in a mitochondrion that passes electrons through a series of proteins and uses those electrons' energy to help make ATP.
At the end of the study, the participants' muscles contained more of the protein machinery involved in producing cellular energy.
Researchers also found higher levels of the proteins involved in helping mitochondria to merge, divide, and reorganize themselves – all important processes for mitochondrial health.
What's more, according to a recent review published in the Frontiers in Cell and Developmental Biology journal, healthy mitochondria depend heavily on a "quality control" system that includes processes like merging, dividing, and repairing or replacing damaged mitochondrial proteins, as well as removing dysfunctional mitochondria.
And different forms of exercise appear to support this quality-control program in different ways...
For instance, endurance training favors mitochondrial renewal, high-intensity interval training ("HIIT") produces strong signals for remodeling and clearing out damaged mitochondria, and strength training helps preserve and improve mitochondrial structure and function.
What's more, exercise can also help keep the mitochondria in our brain healthy...
As we age, our brains develop low-grade, chronic inflammation. That, plus having more damaged mitochondria than healthy ones, raises the risk of cognitive impairment and neurodegenerative diseases.
But getting in some aerobic exercise can help. A study published earlier this year in the Journals of Gerontology looked at neuroinflammation and memory impairment in aging mice. Researchers had the mice undergo an eight-week boot camp of moderate-intensity aerobic exercises.
The result? These mice showed improved mitochondrial health in the hippocampus, or the memory center of the brain. Researchers also observed improved memory and reduced inflammation there.
Speaking of the hippocampus, as we get older, this part of the brain starts shrinking by an average of 1% to 2% per year. But aerobic exercise helps combat that natural shrinkage.
For instance, a 2011 study split 120 healthy older adults into two groups: one that performed aerobic exercise and one that just did stretches. After a year, MRI brain images showed that aerobic exercisers gained 2% in hippocampal volume. On the flip side, individuals who only did stretching lost about 1.4% in hippocampal volume.
My Favorite Way to Keep My Mitochondria Healthy
Longtime readers know I'm a huge fan of HIIT. That's a type of aerobic exercise combining short bursts of "all out" intensity with "recovery" periods of less-intense activity.
Studies have shown that regular HIIT does wonders for rejuvenating your mitochondria. It boosts their size, number, density, and cellular-respiration function.
It also takes less huffing and puffing than you might think...
Even just doing HIIT once a week will suffice. A 2018 study of 250 overweight and obese adults showed that a single 23-minute HIIT session delivers nearly the same physiological benefits (like reducing blood pressure and body fat and improving aerobic fitness) as three moderate-intensity workouts.
You can overdo it, though... A 2021 study in Cell Metabolism found that five weekly HIIT sessions can actually impair mitochondrial function. So stick to no more than two or three sessions per week.
Here's what I do... I walk on a treadmill (or use a bike or aerobic-exercise contraption) at a very slow pace to warm up. Then, I increase the pace to about 2.4 mph (turtles crawl faster). Then, for 20 to 30 seconds, I crank it up to around 5 or 6 mph ‒ or as fast as I can handle without falling all over myself. (Just make sure to be careful – again, the goal is not to hurt yourself.) I also up the resistance by increasing the treadmill's incline to 3% or 4%.
After going at a fast pace at a high resistance for 30 seconds, I slow down and do zero resistance for three or four minutes. I repeat this process a couple more times. In 10 minutes, I'm done. I usually work up a nice sweat by the end.
HIIT isn't my only secret for healthy mitochondria... In a recent issue of Retirement Millionaire, I shared 11 more tips to help keep you (and your mitochondria) young. If you're not already a subscriber, click here to get started... and learn how to keep your retirement years not only healthy, but rich.
If you're already a subscriber, you can read that issue here.
What We're Reading...
- Something different: The trade-offs Americans are making to afford summer travel.
Here's to our health, wealth, and a great retirement,
Dr. David Eifrig and the Health & Wealth Bulletin Research Team
June 16, 2026