Shorter routines involving bursts of high-intensity exercise appear to offer some of the same health benefits as longer programs, Canadian researchers say.

Public health officials recommend 60 minutes of daily exercise, but that can be a challenge to meet.

Canada's physical activity guide for adults recommends 60 minutes of light exercise a day.
(Canadian Press)

"We know that 50 per cent of the population doesn't do it, and the most commonly cited barrier to exercise is lack of time," said Martin Gibala, a kinesiology professor at McMaster University in Hamilton.

Gibala's study, in the September issue of the Journal of Physiology, compared young men doing conventional workouts of 90 to 120 minutes a day with a group doing interval training — 30-second bursts of intense cycling over 20 minutes, three times a week.

The small study involved 16 men over only two weeks, but Gabala was impressed that both groups showed similar improvements in exercise performance and the way their muscles used oxygen.

The study "confirms that interval-based exercise is indeed a very time-efficient training strategy," Gibala said, acknowledging the training is demanding and requires a high level of motivation.

"If we can provide people with an option that's grounded in science to say this is effective, that may be a good public health strategy."

Long-term benefits unknown

The value of shorter, intense exercise is a subject of debate in the fitness world. Last year, Gibala and his team said a few minutes of high-intensity exercise could be as effective as an hour of moderate activity. The latest study directly compared sprint to endurance training.

Dr. Stephen Cheung of Dalhousie University's School of Health and Human Performance in Halifax was also impressed by the results, but he is also cautious.

It's not clear how intense workouts stack up against conventional exercise in other ways, or how long the benefits last, Cheung said.

"We don't know the impact of this kind of a training protocol on things like blood profiles for long-term cardiovascular health, for bone health, weight management issues that are associated with the benefits of exercise."

Doctors say for some, sudden high-intensity activity could be dangerous.

Cheung said the strategy wouldn't be appropriate for people who are starting out as couch potatoes.

The intense training might be a good occasional or complementary workout for people who are already active, but shouldn't replace their regular exercise routine, he said.