by 
HIIT-or high intensity interval training-has been the buzzy sweat?method for sometime now. These fast-paced workouts alternate short bursts of exercise with quick recovery periods, and torch more calories in less time than traditional steady-state training sessions. HIIT can boost metabolism, melt fat, build muscle, and more-and?now, Mayo Clinic scientific study has discovered another benefit: it may reverse aging process at the cellular level.
The study, published in the journal Cell Metabolism, involved 72 sedentary adults in 2 age groups-young (18 to 30) and older (65 to 80). The participants were assigned to one of three 12-week exercise routines: high-intensity interval cycling, weight training with weights, or perhaps a combined strength-training and cycling plan.
The HIIT cycling plan was the most rigorous from the three. It?required?72 hours of cycling (four, 4-minute high-intensity intervals split up by 3-minute recovery periods), and two times of steady, brisk treadmill walking. The strength-training group performed upper- and lower-body exercises just twice a week, as the combined-training group worked out 5 days a week but without intervals, as well as for a shorter period.?
Researchers measured changes in the volunteers’ leg strength, lean body mass, oxygen capacity, and insulin sensitivity. They also biopsied tissue samples and analyzed cells from the volunteers’ thighs pre and post the three-month experiment. After the 12 weeks, all three exercise groups had gained lean muscle and?improved aerobic capacity, but people who did high-intensity interval training workouts (HIIT) got the biggest benefit in the cellular level. Younger volunteers experienced a 49% boost in mitochondrial capacity-the cell’s ability to take in oxygen and produce energy-while older folks experienced a much more dramatic 69% increase.
Mitochondria and ribosomes are organelles that are important for metabolism and aerobic fitness, but tend to deteriorate as people grow older. Keeping these structures healthy can reverse some signs of age-related decline within cells, the researchers.?
“The greater an individual’s mitochondrial capacity, the higher capacity they need to breathe in, transport, and utilize oxygen to do physical exercise and maintain healthy cell function,” explains Paul Arciero, PhD, professor of health and exercise sciences at Skidmore College. “In essence, the health of a cell-and our body-is directly determined by the functioning of the mitochondria.” Arciero was not involved in the new study, but says the results are “very meaningful and somewhat surprising.”?
Neither age group in the strength-training program experienced significant mitochondrial increases. As well as in the combined training group, just the younger group saw improvements.
The HIIT cycling group?also saw improvements in?insulin sensitivity, suggesting this kind of exercise may reduce diabetes risk. It also increased the activity of ribosomes, negligence the cell that builds proteins required to create muscle tissues. That’s important?because muscle cells aren’t easily replaced once they wear out-one reason why people lose muscle mass as they age, explains Sreekumaran Nair, MD, a diabetes researcher at the Mayo Clinic.? ?
Still, HIIT did not build just as much strength or lean body mass over the 12-week period as strength-training did. Dr. Nair says the research wasn’t made to make specific recommendations, but he does suspect that three to four days per week of HIIT plus a couple times of weight training may be the best way to slow the down aging process.?
Co-author Matthew Robinson, PhD, a former Mayo Clinic researcher and now a helper professor of kinesiology at Oregon State University, states that adding short bursts of higher intensities is a great method to gain in benefits from exercise. “It could be trying to find a walking path which includes hills or pedaling faster for a while for people who like to bike,” he told Health in an email, cautioning that individuals who’re a new comer to intervals should progress gradually over several weeks.
While all types of exercise are good for us, Arciero says, HIIT seems to have additional cellular benefits that may, with time, have implications for maintaining muscle, aerobic fitness, and insulin sensitivity as we grow older. “In other words, HIIT mobilizes a powerful army of genes deep within our cells that people don’t understand are helping us in the immediate present time,” he states, “but likely have a delayed or latent effect that will affect the body in very beneficial ways.”
Robinson agrees that “some activity is better than none to promote health during aging,” and states that adding intervals can help the body adapt to new physical demands. “Raising intensity might help people reach their next goals,” he adds, “whether it’s improving fitness or simply being more active.”
