Aerobic Exercise: Jogging, Biking and Swimming Don't Help Everyone Prevent Heart Attacks

It has become conventional wisdom in recent decades that exercise like jogging, swimming biking and other forms of aerobic exercise help prevent heart disease and heart attacks, lowers blood pressure and improves cholesterol health.

But now scientists at the University of London are saying aerobic exercise will benefit most people--but not all.

In fact, according to a new study, about 1 in 5 people get no fitness benefit from aerobic exercise because their fitness depends more on their genes. The study also found benefits of exercise like biking, swimming and jogging vary widely from one individual to another. 

Researchers concluded 20 percent of the population would probably do better by abandoning aerobic exercise and concentrating on a heart healthy diet or taking medication.

The leader of the study, Dr. James Timmons of the Royal Veterinary College at the University of London, said patients will be able to take DNA tests which will guide their doctors' treatment decisions. These DNA tests would also help the patients learn the best ways to maintain fitness and good health, especially where heart health and heart attack prevention are concerned.

"This would be one of the first examples of personalized, genomic-based medicine," Dr. Timmons said.

The DNA tests would also be helpful in other ways. For instance, military recruiters could use the results to screen out would-be recruits who will never be able to reach the required fitness standards.

The results of the study was groundbreaking because it used the human genome - the genetic map of the body - to explore ways to improve health and fitness.

More than 500 individuals in Europe and the US participated in the research. They were asked to do aerobic exercises like biking, jogging, and swimming five times a week, 30 minutes each time. These exercises have traditionally been recommended as ways to improve fitness and reduce the risk of heart attacks and stroke.

80 percent of participants showed measurable improvement in how much oxygen their bodies consumed during exercise, a key indicator of aerobic fitness.

But 20 per cent experienced a a "negligible" increase, according to Dr. Timmons.

Around 30 per cent showed no improvement in insulin sensitivity. In other words, exercise did not lower their chances of getting diabetes. Diabetes has long been considered a major risk factor for heart attack and heart disease.

A pioneering analysis of muscle tissue samples was taken from the participants as part of the study.

Dr Timmons said: “We know that low maximal oxygen consumption is a strong risk factor for premature illness and death so the tendency is for public health experts to automatically prescribe aerobic exercise to increase oxygen capacity."

"Our hope is that before too long, they will be able to target that prescription just to those who may stand a greater chance of benefiting, and prescribe more effective preventive or therapeutic measures to the others.”

The British Heart Foundation recently said that one third of adults in the United Kingdom do their recommended 30 minutes of physical activity a day.

The Human Genomics Laboratory in Louisiana and the Centre for Healthy Ageing at the University of Copenhagen also participated in the study.