A total of 60 seconds of intense exercise can be beneficial as 45 minutes of exercising at a moderate pace, suggests a new study by researchers at McMaster University in Hamilton.
Several studies have shown that interval training can improve cardiovascular fitness. This approach involves working out for a short period then recovering for a period and then going hard again.
In the current study, the research team led by Martin Gibala, a professor of kinesiology at McMaster, recruited 27 sedentary men and divided them into three groups.
The third group participated in 10-minute sprint interval training sessions three times a week. First, they warmed up for two minutes and cycled as hard as they could for 20 seconds, followed by two minutes of easy cycling. The participants repeated the hard sprint and easy recovery twice more, then finished it with a three-minute cooldown.
"The intense interval needed to be quite intense. It's as hard as you can go. It's an all-out effort. So I would use the term 'sprint from danger pace,' or the pace you might cycle at to save your child from an oncoming car," said Gibala.
At the end of 12 weeks training, the fitness levels of the second and third groups were similar, even though the third group had worked out only for about one-fifth the time as the second group.
Participants in the second and third group had increases aerobic endurance. They had better insulin sensitivity scores and better scores on skeletal muscle mitochondrial content, which is a way of measuring their energy production.
Gibala said that the results were yet more evidence that bursts of intense exercise are remarkably effective at improving fitness.
"Our study is a reminder of the potency of interval training. We know that the No. 1 cited reason for why people don't exercise is a lack of time, so we've been interested in developing time-efficient protocols that still boost health and fitness."
"However, this type of exercise is not necessarily safe for everyone and those with certain health conditions would need a gentler approach."
The findings are published online in the journal PLOS ONE.