Research reveals the effects of resistance training breaks on muscle and strength

A study conducted at the University of Jyväskylä’s Faculty of Sport and Health Sciences investigated how a 10-week break from resistance training affected maximal strength and muscle size. The study found that a 10-week break halfway through 20 total weeks of strength training had little effect on development. During rest, maximal strength was better preserved than muscle size.

The study compared the results of 20 weeks of resistance training in two groups, one with continuous training and one with a 10-week break halfway through.

The study found that results for maximal strength and muscle size development were similar in both groups. According to the researchers, the equal progress in both groups was due to the fact that maximal strength and especially muscle size quickly returned to pre-break levels when training was resumed.

“In the first weeks after the break, the progress was very fast and after only five weeks of retraining, the pre-break level had already been reached,” says Eeli Halonen from the Faculty of Sports and Health Sciences, who is writing her PhD thesis on the effects of the training break.

For continuous group training for 20 weeks, progress clearly slowed after the first ten weeks. This meant that ultimately there was no difference in muscle size or strength development between the groups.”

Eeli Halonen, Faculty of Sports and Health Sciences, University of Jyväskylä

“Muscle memory” will be further studied at the cellular and molecular level

The phenomenon where the previous level of muscle size is quickly regained after a break is called “muscle memory”.

“The physiological mechanisms of muscle memory are not yet fully understood,” say senior researchers Juha Hulmi and Juha Ahtiainen, “and our next step is to study more deeply the cellular and molecular changes in muscle that might explain this phenomenon.”

Maximum strength is better preserved than muscle size

The study also found that maximal strength was better preserved during rest than muscle size.

“This could be explained by the fact that changes in the nervous system may be more permanent than peripheral changes in muscles,” says Halonen.

Based on this study and previous evidence, it appears that gym goers have little to worry about with occasional training breaks of up to ten weeks if training is otherwise regular and progressive throughout the rest of the year.

It is worth keeping in mind, however, that in this study those who took a break from training achieved the same result in 30 weeks as those who trained continuously for 20 weeks.

“Of course, the hiatus slows down progress a bit,” Halonen points out, “but it’s comforting to know that it’s possible to get back to pre-hiatus levels surprisingly quickly.”

The study was conducted at the Faculty of Sports and Health Sciences at the University of Jyväskylä. The participants were young Finnish men and women who were physically active but had no prior experience of systematic resistance training.

The results of the study were published in the Scandinavian Journal of Medicine & Science in Sports. The study was funded by the Peurunka Rehabilitation Foundation, the Finnish Sports Research Foundation, the Academy of Finland and the Faculty of Sports and Health Sciences at the University of Jyväskylä.