Contrary to popular belief, a new study suggests taking longer breaks between sets of weightlifting may promote muscle growth.

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Taking longer rests between weightlifting sets may benefit muscle growth, say researchers.

The research reveals that men who had longer rest periods between four weightlifting sets showed a significant increase in muscle rebuilding activity - a process that aids muscle growth - compared with those who had shorter rest periods.

Study co-author Dr. Leigh Breen, from the University of Birmingham in the United Kingdom, and colleagues recently published their findings in the journal Experimental Physiology.

Weightlifting is a form of resistance exercise that involves lifting weights as a way to boost muscle size and strength.

According to the Centers for Disease Control and Prevention (CDC), adults should engage in moderate- or high-intensity muscle-strengthening activities - such as weightlifting - at least 2 days each week, and these activities should incorporate all major muscle groups.

Such activity is recommended in addition to either 150 minutes of moderate-intensity aerobic activity or 75 minutes of vigorous-intensity aerobic activity, in order to reap extra health benefits.

To get the most from weightlifting and other muscle-strengthening exercises, it is recommended that such activities are performed in sets. For example, the CDC suggest performing 8-12 repetitions of lifting a weight in two or three sets to gain extra benefits.

But how long should the rest period be between each set?

Extended rest periods increased myofibrillar protein synthesis

It is widely accepted that an individual should take time to rest between weightlifting sets in order to give the muscles time to recover, but popular notion holds that the shorter the rest time, the greater the muscle growth.

However, the new study from Dr. Breen and colleagues suggests this may not be the case.

To reach their findings, the researchers enrolled 16 men and asked them to complete four sets of weightlifting in the form of a bilateral leg press and knee extension exercise. The men were asked to rest for either 1 minute or 5 minutes between each set.

The researchers took muscle biopsies from the men as soon as all four sets were completed, as well as 4, 24, and 28 hours after.

The biopsies were analyzed to establish levels of myofibrillar protein synthesis (MPS) - the process by which damaged proteins within muscle cells are rebuilt, aiding muscle growth - and intracellular signaling.

Within the first 4 hours after exercise, the team found that the men who had the longer 5-minute rest period between each weightlifting set showed a greater increase in MPS, at 156 percent, compared with those who had the shorter 1-minute rest period, who saw a 76 percent increase in MPS.

Based on their results, the researchers suggest that shorter rest periods between weightlifting sets may actually hinder the muscle growth process.

"With short rests of 1 minute, though the hormonal response is superior, the actual muscle response is blunted.

If you're looking for maximized muscle growth with your training program, a slightly longer interval between sets may provide a better chance of having the muscle response you're looking for."

Dr. Leigh Breen

Rest periods should last at least 2-3 minutes

The researchers recommend that weightlifting novices should take rest periods of at least 2-3 minutes between sets.

"Over time, they may need to find ways to push beyond the plateau of muscle-building that commonly occurs, and so may gradually decrease their rest periods," notes Dr. Breen.

For the more experienced weightlifter, Dr. Breen says it is possible that shorter rest periods may not have such a negative impact on the muscle-building process, particularly if their body has adapted to such stress.

"Nonetheless, similar recommendations of 2-3 minutes between sets should help to ensure maximal muscle growth in well-trained individuals," she adds.

The researchers are now planning to conduct a follow-up study to assess the longer-term impact of extended rest periods between weightlifting sets on muscle growth.

Read about a gene that may help explain the body's varying response to different forms of exercise.