What a HIIT! High-intensity interval training provides same cell benefits in less time

ROCKVILLE, Md. — If you’ve heard about the benefits from high-intensity interval training (HIIT), you should believe the hype. A team of Australian researchers found that when compared to traditional workout routines, HIIT provides the same benefits on a cellular level — in less than half the time.

High-intensity interval training involves short bursts of high-intensity aerobic activity alternated with short recovery periods. A person might sprint on a treadmill for one minute, then slow down to a light jog for two minutes, then return to a sprint for one minute, and so forth.

Researchers from the Institute for Health and Sport at Victoria University in Melbourne say that people who practice HIIT see improvements in mitochondrial function. Mitochondria are the energy centers of the cell and are essential for good overall health.

Existing research found that regular exercise creates new mitochondria and improves the overall function of existing mitochondria. A single session of exercise has been shown to alter mitochondrial function, causing the energy centers to generate signals communicated to other cells and creating beneficial changes, which lowers the risk of chronic disease.

For this latest research, eight volunteers completed three cycling workouts: one with participants moving at moderate intensity (about 50 percent peak effort) for the duration of the workout; one where participants followed an HIIT routine consisting of five four-minute cycling sessions at 75 percent peak effort, each separated by one minute of rest; and a sprint cycling routine consisting of four 30-second sessions at maximum effort, each separated by 4.5 minutes of recovery time.

The authors measured the energy the participants spent on each workout and compared mitochondrial changes in the participants’ thigh muscles before and after each workout.

They found that hydrogen peroxide levels, which are involved in signals between cells, change in different parts of the mitochondria after exercise, creating an optimal metabolic function environment.

“A total of only two minutes of sprint interval exercise was sufficient to elicit similar responses as 30 minutes of continuous moderate-intensity aerobic exercise,” the researchers wrote. “This suggests that exercise may be prescribed according to individual preferences while still generating similar signals known to confer beneficial metabolic adaptions. These findings have important implications for improving our understanding of how exercise can be used to enhance metabolic health in the general population.”

The study was published in the American Journal of Physiology–Regulatory, Integrative and Comparative Physiology.

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