People with lower back pain are better off exercising more, not less, according to a University of Alberta study.

The study followed 240 men and women with chronic lower-back pain and showed that those who exercised four days a week had a better quality of life, 28% less pain and 36% less disability, while those who hit the gym only two or three days a week did not show the same level of change.

“While it could be assumed that someone with back pain should not be exercising frequently, our findings show that working with weights four days a week provides the greatest amount of pain relief and quality of life,” said Robert Kell, lead author of the study and an assistant professor of exercise physiology at the University of Alberta, Augustana Campus.

About 80% of North Americans suffer from lower back pain.

In the study, groups of 60 men and women with chronically sore lower backs each exercised with weights in two, three or four-day weekly programs, or not at all. Their progress was measured over 16 weeks.

The level of pain decreased by 28% in programs that included exercise four days a week, by 18% three days a week and by 14% two days a week. The quality of life, defined as general physical and mental well-being, rose by 28%, 22% and 16% respectively.