Exercise is clearly good for our bodies and our souls, but the challenge of figuring out the optimal exercise regime – in terms of workout frequency, duration, variety and so on – continues to fascinate scientists.

The latest study in this area suggests that the regularity of exercise could be more important than how long the individual workouts last, at least when it comes to strength training using dumbbells.

Through an analysis of the exercise habits of 36 volunteers, the researchers found that short bursts of activity every day built up more muscle strength than longer training sessions that were less frequent.

"People think they have to do a lengthy session of resistance training in the gym, but that's not the case," says Ken Nosaka, a professor of exercise and sports science at Edith Cowan University in Australia.

The participants were split into three groups to perform bicep curls with heavy dumbbells for four weeks. One group did six contractions a day for five days a week, one group did the same 30 contractions a week but crammed them all into one day, and one group did just six contractions for one day a week.

That last group showed no change in muscle strength or muscle thickness (an indicator of muscle size). The other two groups showed the same increase in muscle thickness, but only the group that spread out their exercises developed muscle strength – more than 10 percent on average.

This is only one exercise, but the scientists believe it would apply to other types of workout as well. The main message is that you don't necessarily have to wear yourself out to improve muscle strength and thickness – small but intense bursts are enough, and you can even have two days off a week.

"Muscle adaptions occur when we are resting," says Nosaka. "If someone was able to somehow train 24 hours a day, there would actually be no improvement at all."

"Muscles need rest to improve their strength and their muscle mass, but muscles appear to like to be stimulated more frequently."

The researchers also pointed out that after missing a few days of exercise, it was probably better to simply restart a normal routine again than to try and catch up on the time that had been missed.

Previous research from the same team suggested that just three seconds of exercise a day can deliver results – so for some of us at least, getting regular exercise in every day is more important than spending hours at the gym once or twice a week.

And this isn't just for bodybuilders either: a decrease in muscle mass is linked to a host of different diseases and health issues, including cardiovascular disease, cancer, dementia, type 2 diabetes, and musculoskeletal problems including osteoporosis.

"Muscle strength is important to our health," says Nosaka. "This could help prevent a decrease in muscle mass and strength with aging."

The research has been published in the Scandinavian Journal of Medicine and Science in Sports.