PEOPLE WHO SUDDENLY stop strength training will start to lose significant muscular strength within three weeks, with people over 65 suffering the greatest losses, according to a research review published in the Scandanavian Journal of Medicine & Science in Sports.
Researchers surveyed 103 studies that examined what happens to standard measures of muscular strength when people who had been doing regular strength training suddenly stopped. In amassing the data from all those studies, they focused on three measurements of strength–maximal force, maximal power, and submaximal strength–and tried to discern differences among various groups, such as people age 65 and older, men and women, inactive people versus recreational athletes, etc.
As you might expect, all components of strength declined for all people once they stopped strength training. But there were some interesting differences among the types of strength and types of people who had been doing strength training.
In weightlifting terms, maximal force is your one-repetition max–how much force you can create in one all-out muscular contraction. The researchers found that it starts to decline significantly in the third week after stopping strength training, and keeps declining as more time passes. (The studies the researchers reviewed look at strength declines up to 16 weeks after people stopped strength training.) The researchers speculate that the decline happens in stages that mirror the gains at the beginning of a strength-training program: When you first stop strength training, the decline comes mostly from neuromuscular deterioration; that is, your nervous and muscular systems lose some of their ability to communicate with each other. Over time, the continued decline stems more from changes in the muscles and their surrounding architecture, the researchers hypothesise.
Maximal power is closely related to maximal force, but has a time element to it; it’s your ability to produce high amounts of force over a short period of time, such as a sprint. Because maximal power includes other bodily attributes besides maximal force, it doesn’t decline as rapidly as maximal force does when you stop strength training. In fact, some studies have found a slight increase in maximal power in the immediate aftermath of stopping strength training, most likely because maximal power involves bodily systems that benefit from a short taper. Put another way, Usain Bolt is faster on the morning of the Olympic 100-meter final by virtue of reducing strength training in the few days before. Within a few weeks of stopping strength training, however, maximal power declines similarly to maximal force. But then it doesn’t deteriorate as much over the next several weeks; the researchers speculate that this is because of changes in muscle fiber characteristics related to training.
Submaximal strength is your ability to sustain a high but not close to all-out percentage of maximal force for a long time, such as doing sets of several reps in the weight room. In their review of studies, the researchers found it declined more significantly than maximal force and maximal power. That’s most likely because of accompanying declines in attributes like blood volume and energy production that also happen when you suddenly stop training.
The researchers found that these declines were greater in people over 65 years old. That’s partly because older people are losing muscle mass anyway, so that combined with lack of training accelerates decline, the researchers hypothesise. “These results underscore the importance of following a regular and uninterrupted strength training program in elderly people,” the researchers wrote.
The researchers found no difference in rate of decline between men and women. But they did find that people who were inactive, did some strength training, and then returned to being inactive have steeper declines than recreational athletes. This is almost certainly because the recreational athletes’ other activities maintain some of the attributes, such as neuromuscular coordination, that contribute to the three strength measures. Similarly, people who are new to strength training and then quit decline more rapidly than people with experience; the latter have a more established architecture for producing muscular strength.