And the winner seems to be high-intensity interval training (HIIT), which may yield anti-aging benefits down to the cellular level, the study says.
Researchers enrolled 36 men and 36 women from two age groups—either under 30 or over 65. They took on three different exercise regimes that included high-intensity interval biking, strength training with weights, and one that mixed lighter cycling and lifting. Each group completed their plan for 12 weeks.
Afterwards, the scientists took muscle biopsies to check for changes in lean muscle, and tested for insulin sensitivity, or your body’s ability to effectively use blood sugar.They found that while strength training built muscle mass, it was HIIT that provided advantages on a cellular level. Younger volunteers saw a 49 per cent increase in mitochondrial capacity, and older participants got even more of a boost, with a 69 per cent increase. HIIT also improved insulin sensitivity, lowering the risk of diabetes.
Better mitochondrial function is a big deal, especially when it comes to aging.
Mitochondria—which, if you remember from your high school science class, are called the powerhouses of your cells—are responsible for converting macronutrients into a chemical form of energy called adenosine triphosphate, or ATP. This seemingly simple process is essential for all biological functions. The longer you can keep it efficient, the better off you’ll be.
“Decline is mitochondria is the key factor responsible for age-related physical declines,” says the study’s senior author, Sreekumaran Nair, M.D., Ph.D. That includes osteoporosis, arthritis, gastrointestinal issues, decreased flexibility, hypertension, and cardiovascular issues. “Higher intensity of exercise seems to elicit a rejuvenation of mitochondrial [processes] in everybody, including older people.”
That’s because HIIT seems especially good at boosting mitochondrial proteins, he adds. That leads to better functioning within the cells.
And when your mitochondria goes wonky, your body pays the price: Over the past decade, several studies have noted a causative link between mitochondrial dysfunction and health risks, particularly in the brain and heart. But other organs such as the liver and kidney take a hit, too.
Although the study wasn’t done to develop exercise recommendations to stave off age-related cellular decline, Dr. Nair does have some. He suggests that you start adding in a HIIT workout at least three days a week. Start with 15 minute sessions, he says. For instance, you can sprint for two minutes, then cruise at relaxed pace for one minute. Repeat the cycle 4 more times, for a total of 15 minutes.
Then, as your body gets used to the HIIT, you can add more time to your intervals, he says. For instance, the study participants cycled intensely for 4 minutes, then lightly to recover for 3 minutes. They completed that cycle 4 times total.
Dr. Nair says these recovery periods between high-intensity exercises are important for overall conditioning, because it makes the body more efficient at bringing the heart rate down quickly.
Also, adding resistance training twice a week can help build lean muscle mass, which also has anti-aging benefits: People often lose muscle mass during aging, and that can lead to heightened risks of falls and frailty.
Bottom line? Supplement your thrice-weekly HIIT training with two days of lifting to balance it all out.