Three-second bicep curl, no reps! Reap benefits of minimal exercise

Researchers from Japan and Australia recruited 49 healthy students (“young sedentary individuals… 35 male and 14 female”) and divided them into four groups. One group, of 10 students, did not do any exercise at all. The other students were divided into groups of 13 and performed bicep curls (isometric for one, concentric for another, and eccentric for the last).

The three training groups exerted themselves to the maximum amount (MVC-maximal voluntary contraction) for three - three!– seconds at a time. They did this for five days a week (Monday to Friday), for four weeks.

The control group remained, well, sedentary. All groups’ muscles were measured at the start of the four weeks, and after. They were told not to participate in any exercise outside of the study.

“The control group,” the researchers write, “showed no changes,” as was expected. However, surprisingly, the other groups improved, even though they ‘exercised’ three seconds a day.

“Muscle strength increased more than 10 per cent for the group who performed the eccentric bicep curl after the four weeks,” the news release notes, “but less increase in muscle strength was found for the other two exercise groups.”

Lead researcher Professor Ken Nosaka from ECU’s School of Medicinal and Health Sciences points out that people don’t need to exercise for hours to show benefits to 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,” he says. 

“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.” 

Types of exercise

The study, published in the Scandinavian Journal of Medicine and Science in Sports, examined three types of bicep curls: isometric, concentric and eccentric. They refer to the same upper arm muscle (biceps) being used, but doing different things.

One group of study participants were asked to perform isometric bicep curls. That means the muscle is “stationary under load,” in which case the dumbbell held by their dominant arm is parallel to the ground at 90 degrees to the body, with the elbow bent.

The second group of study participants were asked to perform concentric bicep curls. These students bent and raised their dominant arms with the weight, “shortening” the muscle.

The third group of 13 students were asked to perform eccentric bicep curls. They lowered their dominant arms from a folded position towards the ground, “lengthening” the muscle.

Which group fared better?

According to the authors, all three lifting methods showed improvement to muscle strength, but eccentric contraction by far ended up delivering the best results.

The researchers measured the exercising groups (39 students in total) for their concentric, isometric and eccentric strength after 20 days of exercise was concluded.

The concentric lifting group, the news release says, “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).”

Yet it was the eccentric group that got the best results across all three measurements: concentric increased 12.8 percent, isometric 10.2 percent and eccentric 12.2 percent.

“Performing one 3-second MVC a day increased muscle strength, but eccentric MVC produced more potent effects than isometric or concentric MVC,” the authors write.

The news release notes that the eccentric group’s overall muscle strength improved 11.5 percent after – wait for it – 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,” Nosaka says.

Yes, you can make the time

Nosaka was enthusiastic about the findings, suggesting that they could be useful in the prevention of the loss of muscle mass and strength that happens with aging (sarcopenia), among other things.

“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 says. 

“Also, performing only one maximal contraction per day means you don’t get sore afterwards.” 

Professor Nosaka and NUHW’s Dr Masatoshi Nakamura designed the study and the data were collected by Dr Nakamura and his PhD and Masters students.