Frequent exercise by adults can help delay the aging process, according to a Canadian study.

The study, published in the prestigious science journal Proceedings of the National Academy of Science, used mice to compare the effects of a lifetime of regular exercise over a non-active lifestyle.

The researchers from McMaster University in Hamilton, Ont. worked with a litter of mice that were genetically programmed to age quickly. They then had a select group of mice involved in repeated physical activity, like running on a wheel.

After five months, the mice who exercised not only looked younger, their internal organs were also healthier.

Dr. Mark Tarnopolsky, the study leader, said "Exercise truly is the fountain of youth."

"We were surprised at how effective exercise was," he told CTV News. "It turned out to be more effective than we thought."

Tarnopolsky said that studies have shown non-active people can still take advantage of the benefits of exercise including increased energy, more mobility and healthier organs.