London - Exercise can delay an unhealthy rise in cholesterol by up to 15 years, claim scientists.
Levels of fat in the blood linked to heart disease and strokes usually start to increase as people get older, dropping off in middle age.
But a study found those who were physically fit had better protection against this – with lower levels of total cholesterol and ‘bad’ cholesterol – and did not see a rise until years later.
Researchers measured cardiorespiratory fitness, which is the ability of the heart and lungs to supply oxygen to the muscles during exercise and the muscles’ ability to use that oxygen.
It is improved through aerobic exercise or physical activity that gets you out of breath, and is proven to reduce the risk of heart disease, strokes and other illnesses.
Previous studies have found that unfavourable levels of blood fats are important risk factors for chronic heart disease, while physical activity can improve them.
Assistant professor Dr Xuemei Sui, of the Arnold School of Public Health at the University of South Carolina, said the latest research was designed to assess how healthy men might be able to improve their cholesterol profile by exercising.
The team used data from the Aerobics Centre Longitudinal Study to assess total cholesterol, low-density lipoprotein (LDL) or “bad” cholesterol, high-density lipoprotein (HDL) or “good” cholesterol and triglycerides, another type of blood fat, in 11,418 men.
The participants were observed during health examinations between 1970 and 2006 at the Cooper Clinic in Dallas, Texas.
Cardiorespiratory fitness was measured using a treadmill test and men were placed into low, middle and high fitness categories. The researchers found that total cholesterol, LDL cholesterol and triglycerides all increased up to a certain age and then declined.
The reverse trend was found for “good” cholesterol, which is useful as it helps remove LDL.
Men with poor cardiorespiratory fitness were at risk of developing high cholesterol in their early 30s – but those with good levels of fitness did not see this rise until their mid-40s, around 15 years later.
The unfit group also tended to reach abnormal HDL cholesterol levels in their early 20s, while the fittest men saw normal amounts for their entire lifespan.
Researcher Dr Yong-Moon Park said: “These findings suggest that improving cardiorespiratory fitness levels may delay the onset of dyslipidemia – abnormal lipid levels. Promoting this healthy lifestyle factor may also help to reduce the risk of cardiovascular disease.”
The study, published in the Journal of the American College of Cardiology, did not look at women and it is unclear whether the same effect would be found.
Women are at relatively lower risk of heart disease than men until after the menopause.
Dr Paolo Boffetta, of the Icahn School of Medicine at Mount Sinai, New York, said rates of physical inactivity continue to rise, especially among younger age groups.
He added: “Greater emphasis needs to be made on educating the public on the importance of exercise and clinicians should help counsel patients on fitness.” He said that when questioned, around half of people deem themselves physically active when by any objective measure this is not the case.
Britons are advised to do 150 minutes of moderate activity such as gardening, dancing or brisk walking, or 75 minutes of vigorous exercise including playing sport or running, every week. But three out of four currently fail to achieve this.
Maureen Talbot, senior cardiac nurse at the British Heart Foundation, said: “We already know that regular physical activity can help to increase your ‘good’ HDL cholesterol level and has a valuable role to play in cholesterol control.
“This study, of healthy men only, shows that a good level of cardiorespiratory fitness can delay an increase in their cholesterol levels for a number of years. Other factors affect cholesterol levels too, including a diet high in saturated fat .. it is important also not to smoke, to eat healthily and keep your weight down.”
Daily Mail