Lifting heavy weights three times a week around retirement age could help preserve leg strength into later life, according to new research.

As people age, they naturally lose muscle function. Experts say declining leg strength is a strong predictor of mortality in older people. While earlier studies indicated resistance training could help, the new research provides stronger evidence.

Researchers at the University of Copenhagen found that doing one year of heavy resistance training around retirement age helped maintain significant leg strength for several years.

They reported in BMJ Open Sport & Exercise Medicine that, “In healthy adults of retirement age, one year of heavy resistance training may produce long-term beneficial effects by maintaining muscle function.”

The study included 451 participants from the Live Active Successful Aging (LISA) study, a large randomized controlled trial.

The participants were divided into three groups: one did heavy resistance training, another did moderate-intensity training, and the third did no additional exercise beyond their normal activities.

The heavy weight-lifting group lifted weights three times a week, performing three sets of six to 12 repetitions at 70% to 85% of their maximum capacity. The moderate group did circuit training with body-weight exercises and resistance bands.

The researchers measured bone and muscle strength and body fat levels at the beginning, and then again after one, two and four years.

After four years, complete data was available for 369 people. By the end of the study, the average age was 71 years, with 61% being women.

The results showed that people in the heavy weight lifting group maintained their leg strength over time, while people in the moderate and no exercise groups lost strength. The preservation of leg strength in the heavy weight lifting group may be due to changes in the nervous system in response to resistance training.

The study found that participants were generally more active than the average population, walking about 10,000 steps a day, so they may not be representative of the general population.

The researchers concluded that, “This study provides evidence that resistance training with heavy loads at retirement age can have long-term effects for many years.”