Exercise is hard work, but it pays. Adding to the many reasons to get moving is repeatedly compelling research about two exercise methods that can help prevent cellular aging: high-intensity interval training (HIIT) and endurance training.
What are these exercise methods, and why do they work?
The anti-aging response
In a study published in the European Heart Journal, researchers examined the cellular effects of different exercise interventions. Over 6 months, 124 participants were instructed to perform one of three modalities: endurance training, HIIT, or resistance training (using free weights, weight machines, resistance bands, or bodyweight exercises to increase muscular strength). Some participants were assigned to a control group and instructed to make no change to their exercise regimen.
After 6 months, researchers found that HIIT and endurance training, but not resistance training, increased telomerase activity, which is beneficial for cell growth and replication. Telomeres are nucleotide sequences found at the end of chromosomes that protect our genetic information. When they shorten, cellular aging occurs. HIIT and endurance training were found to increase telomere length, inhibiting cell death, and ultimately producing an anti-aging effect.
Similar results were reported in Cell Metabolism, in a study that compared the metabolic responses from HIIT and resistance training. Participants were placed in cohorts by age (<30 and >65), and randomized to one of three exercise routines: HIIT, resistance training, or a combination of both. After 12 weeks, all exercise routines resulted in improved fitness, boosted insulin sensitivity, and increased lean mass, but HIIT training increased aerobic capacity and mitochondrial function, leading to a reduction in mitochondrial decay, which contributes to aging.
For older adults, HIIT training yielded the most significant reversal in cellular aging. Participants over 65 saw a 69% increase in mitochondrial respiration—the metabolic process within mitochondria that converts energy into adenosine triphosphate (ATP), the universal energy donor in our cells. Additionally, adults under 30 saw a 49% increase. Resistance training did not provide this effect in either age group.
According to senior author Sreekumaran Nair, MD, PhD, “Any exercise is better than being sedentary.” Still, he noted that for older adults, HIIT is a highly efficient way to counteract many age-related changes.
Best part? HIIT training has also been proven to be the best exercise method to reduce body fat.
Huge benefits, little time commitment
HIIT has gained popularity because it brings powerful benefits without a large time commitment, especially compared with endurance training, which requires long stretches of time. This was demonstrated in a research trial following two groups of sedentary men: one group performing a 10-minute workout with sprint intervals, and another performing 50 minutes of continuous exercise. After 12 weeks, researchers found that both groups saw equal improvements in cardiometabolic health, despite the 40-minute difference in time commitment. In summary, research shows us that HIIT is more efficient than endurance training.
Effectiveness is a different question. Fortunately, it can be answered simply. Which of these routines are you most likely to stick to? That’s the most effective anti-aging workout for you.
“Not everyone reacts to exercise in the same way,” said Daniel Green, PhD, a professor of exercise science at the University of Western Australia, in an interview with The New York Times. “But there is something out there that will benefit almost everyone.”
HIIT and endurance training
HIIT combines short bursts of all-out exercise followed by short periods of rest. Intense work intervals generally last from 15 seconds to 4 minutes, and are performed to achieve 80% to 95% of a person’s maximum heart rate. Recovery intervals last about the same time and are performed at a much lower intensity: 40% to 50% of maximum heart rate. The work/recovery interval is repeated several times, comprising a quick workout between 10 to 40 minutes total. A HIIT regimen can involve treadmills or rowing machines, bodyweight exercises, free weights, or no equipment at all.
Here’s an example of a 10-minute beginner HIIT workout, completed in three rounds with no equipment. For each step, use maximum effort for 45 seconds, then rest for 15 seconds:
Keep in mind that this is just a single example. The exercises can vary, so swap in your favorite moves. The key is to dig deep and use maximum effort, regardless of exercise type.
Endurance training is a continuous form of exercise, typically performed at sub-maximal intensity for sessions that range from 30 minutes to several hours. This type of training aims to build endurance, which allows a person to exert long bouts of effort without becoming fatigued. Popular endurance sports such as running, swimming, and cycling are good examples of endurance training, characterized by repeated isotonic contractions of large muscle groups. You can also practice endurance training by performing just about any aerobic exercise (jump rope, lunges, dancing, kickboxing, and more) at a low level of resistance over relatively long periods of time without rests, or with minimal rests in between.