Those who exercise on a regular basis will occasionally have to take a break for one reason or another such as an injury or vacation, but you don't need to feel guilty when that happens. Researchers at the University of Jyväskylä in Finland found a 10-week break in the middle of a 20-week strength training routine had little effect on the overall development of the participants.

That's good news for those worried about losing ground they believe might not be recovered if they have to hit pause.

Researchers from the University's Sport and Health Sciences team wanted to see what impact a 10-week break from resistance training had on maximum strength and muscle size and published their findings in the Scandinavian Journal of Medicine & Science in Sports. What they found out is the strength returned quicker than the muscle mass, but both eventually were almost the same after 20 weeks as those who did not stop in the middle.

The study consisted of two groups of physically active men and women without any previous strength training experience. They all completed a 20-week resistance training program. One worked for 20 consecutive weeks, while the other took a 10-week break in the middle. The maximum strength and muscle size development for both groups was similar when the study was complete, which researchers said was due to the fact that the strength and size quickly returned to pre-break levels after the participants started training again.

"During the first few weeks after the break, progress was very rapid and after only five weeks of re-training, the pre-break level had already been reached," said researcher Eeli Halonen. "For the group training continuously for 20 weeks, progress clearly slowed after the first ten weeks. This meant that there was ultimately no difference in muscle size or strength development between the groups."

Researchers used the term "muscle memory" to describe the quick return to form. "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 in more depth the cellular and molecular changes in muscles that could potentially explain this phenomenon."

Halonen addressed the fact strength was better preserved and muscle mass by saying, "This could be explained by the fact that changes in the nervous system may be more permanent than peripheral changes in the muscles."

One drawback for those who took the break in the middle is it actually took them a total of 30 weeks to end up where others did in 20 weeks.

"Of course, the break slows progress some," Halonen said, "but it is comforting to know that it is possible to reach the pre-break level surprisingly quickly."

Click here to read more in the Scandinavian Journal of Medicine & Science in Sports.