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Just three seconds a day of intense weight training could be enough to improve your strength, especially if you're new to exercise, suggests a small study published February 1 in the Scandinavian Journal of Medicine and Science in Sports.
Researchers from Edith Cowan University in Australia and Niigata University in Japan looked at 39 healthy college students over a four week period of working out. Another ten students did not work out, but were monitored as a control group.
For five days a week, participants performed one of three different bicep curl variations: isometric (holding the weight parallel to the ground), concentric (raising the weight) or eccentric (lowering the weight).
Each exercise was three seconds of max effort using a special resistance machine. Researchers measured participants' strength in each of the exercise types before and after the four weeks.
At the end of the study, participants were about 10% stronger, on average, by doing a total of 60 seconds of exercise during the course of the month.
The results suggest small doses of exercise could pay off for strength gains, although beginners will likely benefit the most, according to Ken Kazunori Nosaka, co-author of the study and professor of exercise science at Edith Cowan.
"'No time for exercise' is the most common excuse not to do exercise regularly, but exercise for 3 seconds may not affect time so much," he told Insider.
Nosaka said one muscle contraction a day is surprisingly effective for strength improvements, even more so than six muscle contractions a day, a follow-up study found.
"This suggests that frequency is important. So, we should be doing a small amount of exercise every day," he said.
A caveat, though, is that max effort lifts are difficult to do with barbells or dumbbells. Researchers are still studying whether less intense efforts could also be effective, and if other muscles beyond the biceps can be strengthened with the three-second protocol.
Previous research suggests that you can similarly reap the benefits of aerobic (cardio) training with short, frequent bursts of exercise such as Tabata or HIIT.
Three seconds may not be long enough to build muscle, however. While study participants got stronger, their muscle size didn't increase significantly, suggesting the gains were neurological.
Muscle growth is a slow process no matter how you train, and evidence still suggests longer, high-volume weight sessions may be useful. However, with the right training, you can build muscle in as little as two days a week, according to evidence.
While all the exercise groups in the study improved, one exercise stood out.
Study participants who performed max effort eccentric exercises that involve lengthening the muscle (similar to lowering a dumbbell from the top of a curl) were significantly stronger. They improved by about 11.5% on average compared to their starting efforts, and improved at all three types of exercise, compared to the other groups, who were stronger at only one type of exercise.
Previous studies also suggest eccentric exercise might be superior for strength gains.
Eccentric exercise is also easier for challenging yourself with nearly max effort using a dumbbell, Nosaka said. To try it, choose a weight you can't lift with one arm, but can lift with two. Use your other arm to help position the weight in the top of a curl, and then slowly lower it down with your working arm to get an intense eccentric contraction.
Eccentric exercises are also useful for improving at other challenging movements like deadlifts, push-ups, and pull-ups without compromising good form, trainers previously told Insider.
