Short bursts of intense activity may be more beneficial: Study

Washington: Shorter bouts of intense exercise may produce more health benefits than hours of moderate-level physical activity, according to a study.

Experts have long agreed that adults should aim for roughly 150 minutes of moderate physical activity per week, said researchers from the Arizona State University (ASU) in the US. When the guidelines were first published in 2008, it was thought that in order to obtain meaningful health benefits, those 150 minutes had to be accrued in bouts of at least 30 minutes of activity at a time, they said. The researchers have been working together for over a decade to research the effects of high-intensity interval training (HIIT) -- characterised by short bursts of intense activity -- on various health outcomes.

In more than one study, they found that HIIT was better than traditional, continuous bouts of exercise at lowering blood pressure. "Short bouts always do as well and sometimes better than longer bouts," said Glenn Gaesser, a professor at ASU. A common misconception about HIIT is that it's too difficult for the average person. In actuality, HIIT is tailored to an individual's personal capabilities. The principle is to do just enough physical activity to elevate your heart rate to the point just before you start to feel fatigued -- which is different for everyone -- and then stop, researchers said.

Generally, one HIIT bout takes anywhere from 30 seconds to a few minutes. "You can rest for as much or as little time between each bout as you like, as long as you do enough bouts each week to add up to 150 minutes, researchers said. "That makes it easy to incorporate HIIT into a busy schedule; on a regular workday, you can get 30 minutes of physical activity in by taking a few minutes' break every hour to climb the stairwell or take a brisk walk around the office building," they said. In an animal study, less than 10 per cent of rats dosed with HIIT before receiving chemotherapy died from cardiac-related reasons, while roughly 50 per cent of rats who were not dosed with HIIT before chemotherapy died from heart failure.

"It was night and day," said ASU Assistant Professor Siddhartha Angadi. "And when we looked at their hearts via electron microscopy, the hearts that got the chemo without exercise were just wrecked. Whereas the hearts that got exercise before the chemo were relatively preserved," Angadi said. Initial results of the first human trials taking place at Angadi and Gaesser's lab indicate that hearts of patients dosed with HIIT are faring better than those in a control group who were only asked to walk 10,000 steps each day.