Lifting weights for as little as three seconds a day can have a positive impact on muscle strength, new research has revealed.
The study, conducted by researchers from Edith Cowan University (ECU) in Western Australia and Niigata University of Health and Welfare (NUHW) in Japan, had 39 healthy students perform one muscle contraction at maximum effort for three seconds per day for five days a week, over a four-week period.
The participants performed either an isometric, concentric or eccentric bicep curl at maximum effort, while researchers measured the muscles' maximum voluntary contraction - a standardised method to measure muscle strength - before and after the four-week period.
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 the weight sees the bicep in concentric contraction, lowering the weight sees it in eccentric contraction, while holding the weight parallel to the ground is an isometric contraction.
Another 13 students performed no exercise over the same four-week period and were also measured before and after.
After the four weeks, more than 10 percent of the group who performed the eccentric bicep curl saw an increase in muscle strength - however, the other two groups saw less of an increase. The no exercise group saw no increase.
The study, published in the Scandinavian Journal of Medicine and Science in Sports, found that people don't need to spend vast amounts of time exercising to improve their muscle strength.
"The study results suggest that a very small amount of exercise stimulus - even 60 seconds in four weeks - can increase muscle strength," lead researcher Professor Ken Nosaka from ECU's School of Medical and Health Sciences said.
"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."
So which contraction is best?
All three of the lifting methods - isometric, concentric and eccentric - offered some benefit to muscle strength, the study found, but eccentric contraction easily produced the best results.
Researchers measured each group's concentric, isometric and eccentric strength. The concentric lifting group improved slightly (6.3 percent) in isometric strength, but saw no improvement elsewhere, while the isometric group only saw an increase in eccentric strength (7.2 percent).
However, the eccentric group saw significant improvements in strength across all three measurements - concentric increased 12.8 percent, isometric increased 10.2 percent and eccentric rose by 12.2 percent.
The eccentric group's overall muscle strength improved 11.5 percent after 60 seconds of effort in total.
"Although the mechanisms underpinning eccentric contraction's potent effects are not clear yet, the fact that only a three-second maximal eccentric contraction a day improves muscle strength in a relatively short period is important for health and fitness," Prof Nosaka said.
Prof Nosaka said the findings are exciting for the future of physical fitness and health and may help in the prevention of sarcopenia - a decrease in muscle mass and strength with aging.
"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."
Prof Nosaka and NUHW's Dr Masatoshi Nakamura designed the study and the data was collected by Dr Nakamura and his PhD and Masters students.
