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Don’t Lift Weights – Lower Them Instead

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A new study reports that slowly lowering weights builds and strengthens muscles almost as well as lifting and lowering them, as you would do with a typical rep. That means, for example, that you could use two hands to lift a dumbbell, then one hand to slowly lower it, while sacrificing little in the way of results. Focusing on the lowering – or the “eccentric” contraction – can lead to a more efficient gym session, Japanese researchers say.

In the study, published in the European Journal of Applied Physiology, researchers divided people into three groups of 14 for a 5-week, twice-weekly comparison. One group performed dumbbell curls from full extension to about one-quarter of the way up, for 2 seconds up and 2 seconds down, in three sets of 10 reps. Another 14 people performed only the lift portion of the movement (a researcher helped them reset the weight after each rep), and another 14 did only the lowering part of the move. The group that both lifted and lowered the weights increased the maximum force they could produce on a lift by 18%, and increased the thickness of the biceps muscle by 11%. The people who only lowered the weights nearly matched that, increasing their maximum force by 14% and muscle size by 10%. The lifting-only group increased their max force by 11%, while muscle size increase was insignificant.

Your muscle fibers work two ways. When you lift a dumbbell from a straight arm up to your shoulder, your biceps muscle is using a “concentric” contraction. As you lower that dumbbell back down, the biceps muscle is working to put the brakes on the descent – that’s called an “eccentric” contraction.  The lifting-plus-lowering group saw the biggest gains because they were pretty much doing twice the number of reps. The lowering-only group made similar improvements in strength and muscle with only half the work.

Study author Masatoshi Nakamura, PhD, a professor at Nishikyushu University in Japan, believes that eccentric muscle contractions produce greater neurological adaptations in the spine and brain than concentric contractions. In other words, your nerves learn to send more of the “pull harder” signal to your muscles. At the same time, the spring action of a large protein called “titin” in the muscle fibers produces greater force during eccentric contractions while using less energy, and more titin could account for the increase in muscle size, which is called hypertrophy. “Titin in the muscle fibers could be the best explanation for muscle hypertrophy,” Nakamura says. “However, we believe that other factors, such as neurological adaptations, also play a large role in increasing muscle strength.”

The short range of motion used in the dumbbell curls was an important factor. A 2019 study in the Journal of Strength and Conditioning Research found that a partial range-of-motion triceps exercise produced greater muscle growth than full range-of-motion movements.

Sources:
Masatoshi Nakamura, PhD, professor, Nishikyushu University.
European Journal of Applied Physiology: “Comparison between concentric-only, eccentric-only, and concentric-eccentric resistance training of the elbow flexors for their effects on muscle strength and hypertrophy.”

Based on: https://www.medscape.com/viewarticle/985188?src=