Thirty minutes of daily exercise is enough

August 26, 2012 - 06:53

The same effect in only half the time: scientists have demonstrated that 30 minutes of daily exercise gives an equally effective loss of weight and fat mass as a full hour’s daily exercise.

‘Less is more’ now also appears to apply to exercise and weight loss, new study finds. (Photo: Wikimedia Commons)

Exercising for a full hour rather than a half does not provide any additional loss in either body weight or fat, a new Danish study shows.

Over a three-month period, scientists monitored 60 overweight, but healthy, Danish men in their efforts to improve their physical fitness.

One half were asked to work out one hour a day, wearing a heart rate monitor and a calorie counter. The other half exercised for 30 minutes.

The results show that 30 minutes of exercise intense enough to produce a sweat is enough to turn the tide on an unhealthy body mass index.

“The men who exercised 30 minutes a day lost an average of 3.6 kilos in three months, while the full-hour group only lost 2.7 kilos,” one of the researchers, PhD student Mads Rosenkilde, says in a press release from Copenhagen University.

“Both groups had a reduction in body mass of around 4 kilos.”

And there’s an additional bonus to exercising for 30 minutes:

The men who exercised 30 minutes a day lost an average of 3.6 kilos in three months, while the full-hour group only lost 2.7 kilos.
Mads Rosenkilde

”The men who exercised 30 minutes a day burned more calories than they should in relation to the exercise programme they were assigned to. Those who exercised the most lost too little weight relative to the energy they burned by running, cycling or rowing,” he says.

“So a half hour’s worth of concentrated exercise provides equally good results on the weighing scale.”

Motivation to exercise

The researcher reckons that part of the explanation for these surprising findings is that a 30-minute workout is sufficiently manageable for the participants to be motivated for even more physical activity after their daily exercise session.

It’s also possible that the group doing the full hour exercises ate more and consequently lost slightly less weight than expected, he adds.

An increase in muscle mass may also have had a bearing on the results, and that’s something the scientists are currently trying to find out.

”The participants exercised every day over a three-month period. All the sessions were meant to produce a light sweat, but three times a week they were asked to step up a gear.”

The next step involves studying the effects of other forms of exercise:

The men who exercised 30 minutes a day burned more calories than they should in relation to the exercise programme they were assigned to. Those who exercised the most lost too little weight relative to the energy they burned by running, cycling or rowing.
Mads Rosenkilde

“Another exciting scenario would be to study exercise as a form of transport,” he says. "Exercise is great for your physical and mental health. The problem is that it’s time-consuming. A lot can be gained if we can get people to exercise on the go – for instance on the way to work.”

On the right wavelength

The new findings are unique in that the participants belong to the large, but frequently overlooked, group of moderately overweight men who have gradually come to make up 40 percent of the male population in Denmark.

The 60 men in the study wanted to change their lifestyles with exercise, and in the three-month period, they were monitored closely by health science researchers with a focus on energy balance, insulin resistance and hormones in the blood.

They were also monitored by ethnologists hoping to uncover the cultural barriers associated with exercise and a change in old habits.

The broad interdisciplinary approach in project FINE – a Danish acronym for Physical Activity for a Long Healthy Life – has generated some extremely solid data. Very few participants dropped out, thanks to the focus on their motivation to exercise early on and during the process:

”We’ve really been on the same wavelength as our test subjects – and the FINE study covered the full range of training – physical and mental aspects alike,” says the researcher.

The findings are published in the American Journal of Physiology.

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