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/ Source: TODAY
By A. Pawlowski

Don’t have much time to exercise? More evidence shows it’s not a problem — if you just work out harder.

A total of only two minutes of vigorous interval exercise had similar beneficial effects on a person’s body as 30 minutes of continuous moderate intensity aerobic exercise, a small new study has found. The research is the latest to show that short-but-intense workouts can be surprisingly effective.

Still, people should be aware they have to push themselves very hard for it to work, said lead author Adam Trewin, a researcher at the Institute for Health & Sport at Victoria University in Melbourne, Australia.

“This type of sprint exercise might be best used as 'icing on the cake' in addition to other regular forms of exercise, since the difficulty of the sprint exercise used in this study should not be underestimated,” Trewin told TODAY.

“For many people, this might not be enjoyable and/or tolerable to perform regularly.”

Going all out

The study, recently published in the American Journal of Physiology — Regulatory, Integrative and Comparative Physiology, involved eight young healthy, active people. They did three types of workouts on a stationary bike:

  • 30 minutes of continuous cycling at a moderate pace.
  • Five cycling intervals, lasting four minutes each, performed at 75 percent peak effort. Each was followed by one minute of recovery time.
  • Four 30-second “all out” intervals performed as hard and fast as the participants could pedal, separated by 4.5 minutes of recovery time.

The researchers then looked at the mitochondrial responses in the participants’ thigh muscles after each type of workout. Mitochondria are often described as the powerhouse of the body’s cells, so they’re particularly important for maintaining energy levels in muscle when people exercise, Trewin said.

They also carry out a range of other vital cellular processes to maintain optimal health, he added. Regular exercise is known to increase the amount of mitochondria in muscles.

It turned out the brief sprint exercise led to the same mitochondrial responses in the participants’ thighs as the longer cycling workouts, “despite consisting of considerably less total work,” the study found.

“Your body needs to experience a certain amount of stress from doing exercise to achieve beneficial adaptations for health,” Trewin explained. “It appears that this can be achieved either by performing exercise for a sufficient duration or at a sufficient intensity.”

Previous studies have shown high‐intensity interval training similar to the sprint sessions in the study also had cardiovascular benefits and led to weight loss.

After researchers at McMaster University reported in 2016 that a 10-minute workout could be just as effective as a 45-minute session, TODAY's Sheinelle Jones tried it for three weeks. She performed 10-minute workouts, three times a week, with one minute of each workout devoted to high intensity effort, broken into 20-second bursts. Tests showed she increased her maximal aerobic capacity and boosted her fitness level.

“It’s definitely one of those things where if you don’t have enough time, it’s worth it,” she said afterwards.

"If you're willing and able to go hard, it would appear that you can get away with a surprisingly small dose of exercise and still boost your fitness," added Martin Gibala, professor and chair of the department of kinesiology at McMaster University and lead researcher of the study.

Tips to remember:

Any time you want to try a new exercise program, especially high intensity exercise, check with your doctor first, Trewin said.

Remember: You have to push yourself to the max during the 30-second “all out” sprints. The motto is “peak intensity.” When you’re going at that pace, it may seem like the longest 30 seconds ever.

Since exercise can boost a person’s mood and relieve stress, a sprint may not provide the same mental health benefit as a 30-minute workout. Jones found her brief sessions didn’t clear her head as much as her usual routine.

The high intensity option can be a great part of a person’s fitness lifestyle, said Dr. Jordan Metzl, a sports medicine physician and fitness instructor. You don’t have to replace all of your workouts with super short sessions — just add them to your routine when needed.

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