Washington, May 21: Want to stay young? According to a study, exercising four to five days a week can slow down your heart's ageing. The optimal amount of exercise required to slow down the ageing of the heart and blood vessels has long been a matter of vigorous debate. As people age, arteries - which transport blood in and out of the heart - become prone to stiffening, which increases the risk of heart disease.

Whilst any form of exercise reduces the overall risk of death from heart problems, this new research shows different sizes of arteries are affected differently by varying amounts of exercise. Two-to-three days a week of 30 minutes exercise may be sufficient to minimise stiffening of middle-sized arteries while exercising four-to-five days a week is required to keep the larger central arteries youthful.

The authors performed a cross-sectional examination of 102 people over 60 years old, with a consistently logged lifelong exercise history. Detailed measures of arterial stiffness were collected from all participants, who were then categorised in one of four groups depending on their lifelong exercise history: Sedentary: less than two exercise sessions/week; Casual Exercisers: Two-to-three exercise sessions per week; Committed Exercisers: four-to-five exercise sessions/week and Masters Athletes: six-to-seven exercise sessions per week. (NB: an exercise session was at least 30 minutes).

Upon analysing the results, the research team found that a lifelong history of casual exercise (two-to-three times a week) resulted in more youthful middle-sized arteries, which supply oxygenated blood to the head and neck. However, people who exercised four to five times per week also had more youthful large central arteries, which provide blood to the chest and abdomen, in addition to healthier middle-sized ones.

The fact the larger arteries appear to require more frequent exercise to remain youthful will aid the development of long-term exercise programmes. They also enable the research team to now focus on whether or not the ageing of the heart can be reversed by exercise training over a long period of time.

"This work is really exciting because it enables us to develop exercise programmes to keep the heart youthful and even turn back time on older hearts and blood vessels. Previous work by our group has shown that waiting until 70 is too late to reverse a heart's ageing, as it is difficult to change cardiovascular structure even with a year of training. Our current work is focussing on two years of training in middle-aged men and women, with and without risk factors for heart diseases, to see if we can reverse the ageing of a heart and blood vessels by using the right amount of exercise at the right time," said Benjamin Levine, one of the authors of the study. The study has been published in The Journal of Physiology.