A new study indicates that lowering weights slowly without lifting them builds muscle and strengthens them, compared to if they were lifted and lowered.
For example, you can use both hands to lift a dumbbell, and then use one hand to slowly lower it. Japanese researchers say that focusing on (eccentric) moving away from the center of the body outward can lead to a more efficient gym session.
In a study, published in the European Journal of Applied Physiology, researchers divided people into three groups of 14 for comparison periods for 5 weeks, twice a week.
One group performed dumbbell raises from full forearm extension to flexion about a quarter of the way up, for two seconds up and two seconds down, in 3 sets of 10 repetitions. Another 14 people did only the lifting part of the movement, and the remaining 14 people only did the lowering.
The group that lifted and lowered the weights increased the maximum force they could produce on the lift by 18% and increased the thickness of their biceps by 11%.
The people who just lowered the weights nearly matched this, increasing their maximal strength by 14% and muscle size by 10%.
The lifting-only group increased their maximal strength by 11%, while the increase in muscle size was minimal.
Muscle fibers work in two ways. When you lift a dumbbell from a straight arm to your shoulder, your biceps uses a concentric contraction. As you lower the dumbbell, your biceps restrains the drop and this is called an eccentric contraction.
The lifting and lowering group saw the biggest gains because they were doing pretty much twice as many exercises. The drop-only group achieved similar improvements in strength and muscle with only half the work.
Study author Masatoshi Nakamura, Ph.D., a professor at Nishikyushu University in Japan, believes that decentralized muscle contractions produce greater neural adaptations in the spine and brain than central contractions. In other words, your nerves are learning to send more of the “pull harder” signal to your muscles.
At the same time, the spring action (as a spring or metal spring moves) of a large protein called Titin in muscle fibers results in more force during eccentric contractions while using less energy, and more Titin can lead to an increase in muscle size, which is called hypertrophy.
“The Titin in muscle fibers could be the best explanation for muscle hypertrophy,” Nakamura says. “However, we believe that other factors, such as neural adaptations, also play a large role in increasing muscle strength.”
The short range of motion used to lift dumbbells was an important factor. A 2019 study in the Journal of Strength and Conditioning Research found that partial-range-of-motion triceps exercises produced more muscle growth than full-range-of-motion exercises.
