Which phase of lifting weights yields more muscle growth? Researchers find out

Does the eccentric phase really generate more gains?

By Steph Green Published February 12, 2025

Man doing dumbbell concentration curls — Monkey Business / Adobe Stock

There are two main phases of lifting weights: eccentric and concentric. The eccentric phase is where you lengthen the muscle, and the concentric phase is when you contract or shorten the muscle. While previous studies suggest that the eccentric or lengthening phase of lifting yields the most muscle growth, a new study challenges this notion.

Research has shown the many benefits of resistance training and weightlifting, including building muscle, and more researchers are delving into the nitty gritty of pumping iron. Recently, researchers set out to compare eccentric and concentric training to determine which yields more hypertrophy, which refers to an increase in muscle size. Does the eccentric phase really generate more gains? Let’s look at the new research.

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The study

man leaning over to perform deadlift using lifting straps wrist strap — RDNE / Pexels

In a review published in the Journal of Strength and Conditioning Research, researchers analyzed 26 studies involving 682 healthy adults. The goal was to assess the effects of eccentric muscle actions compared to eccentric muscle actions on muscle hypertrophy.

The results

Man doing deadlifts — Victor Freitas / Pexels

The results revealed that there was no significant difference between concentric and eccentric muscle actions when it comes to increasing muscle size. Both eccentric and concentric muscle actions delivered similar hypertrophy results in healthy adults.

The review did show that certain subgroups experienced some benefits with eccentric training under specific conditions.

Concluding thoughts

A bearded man doing a biceps curl — Anete Lusina / Pexels

More research is needed on the effects of eccentric compared to concentric muscle actions, and the results of this study don’t align with previous research. For example, an earlier study revealed that we can generate up to 40% more force loading the muscle in the eccentric phase of the lift compared to the concentric. In other words, we have more strength during the eccentric phase of lifts and more mechanical tension that fuels muscle building.

The majority of the data suggests that the eccentric or lengthening phase of lifting yields the most muscle growth. Many fitness experts and powerlifters recommend going through the full range of motion when lifting to get the best results.

Steph Green is a content writer specializing in healthcare, wellness, and nutrition. With over ten years of experience, she…

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