Having no time to fit exercise into a busy schedule may not be an excuse for much longer.
A new Edith Cowan University study, published in the Scandinavian Journal of Medicine and Science in Sports, shows lifting weights for as little as three seconds a day at maximum effort can improve muscle strength.
Lead researcher Ken Nosaka from ECU's School of Medical and Health Sciences collaborated with researchers from Niigata University of Health and Welfare in Japan.
The study involved 39 healthy university students performing one muscle contraction at maximum effort for three seconds per day for five days a week over four weeks.
"In this particular study, we wanted to know the minimal stimulus for the muscle to get stronger," Professor Nosaka told Tom Baddeley on ABC Radio Perth.
The students performed either an isometric, concentric or eccentric bicep curl at their maximum effort while researchers measured the muscle's maximum voluntary contraction strength before and after the four-week period.
Another 13 students performed no exercise over the same period and were also measured before and after the four weeks.
Muscle strength increased more than 10 per cent for the group which performed the eccentric bicep curl after the four weeks, but less increase in muscle strength was found for the other two exercise groups.
The no-exercise group saw no increase.
Lengthy workouts might not be necessary
Professor Nosaka said the research demonstrated people did not need to dedicate long periods of time to see the benefits of exercise.
"Many people think you have to spend a lot of time exercising, but it's not the case.
"Short, good-quality exercise can still be good for your body and every muscle contraction counts."
Muscle weakening with age
Professor Nosaka said the findings were exciting for developing programs for the ageing population and could help prevent age-related diseases.
"We haven't investigated other muscles yet, but if we find the three-second rule also applies to other muscles, then you might be able to do a whole-body exercise in less than 30 seconds," he said.
"Also, performing only one maximal contraction per day means you don't get sore afterwards."
Isometric, concentric or eccentric lifting?
The study showed all three lifting methods had some benefits for muscle strength, however eccentric contraction easily produced the best results.
An isometric contraction is when the muscle is stationary under load, concentric is when the muscle is shortening, and eccentric is when the muscle is lengthening.
Lifting a dumbbell up from your side sees the bicep in concentric contraction, lowering the weight sees it in eccentric contraction, while holding the weight parallel to the ground is isometric.
The concentric lifting group improved slightly (6.3 per cent) in isometric strength but saw no improvement elsewhere, while the isometric group only saw an increase in eccentric strength (7.2 per cent).
However, the eccentric group saw significant improvements across all three strength measurements: concentric increased 12.8 per cent, isometric 10.2 per cent and eccentric 12.2 per cent.
The eccentric group's overall muscle strength improved 11.5 per cent after 60 seconds of effort in total.
