Exercising is healthy, even or perhaps especially later in life. It also matters what you do, according to a new international study: Strength training in particular has an effect. Even four years later, the effects can still be seen.

“If you do resistance training later in life, the benefits can last for several years,” said lead researcher Mads Bloch-Ebbenfeldt from the Institute of Sports Medicine in Copenhagen.

Study participants had to follow one of three different workouts for a year: lifting weights three times a week, moderately intense training three times a week using body weight and resistance bands, or exercising as usual.

Stronger legs after four years

The researchers measured bone and muscle strength and body fat percentage at the beginning of the study, at the end of the one-year program, and then after two and four years.

The study found that resistance training provided the greatest long-term benefit in leg strength. Even after four years of training, the participants’ leg strength did not change, while the other two groups developed weaker legs.

“Exercise is crucial throughout life. This study shows that even those who are active later in life, in retirement, enjoy clear health benefits,” said researcher John Patsis of the University of North Carolina.

Resistance or strength training works best. Think of these exercises as “exercises that improve strength by making the muscles work against force,” says CNN fitness contributor Dana Santas. This force can include weights, resistance bands, or your own body weight, as with push-ups or squats. “For older adults, resistance training is critical for maintaining muscle mass, bone density, and mobility,” she said.