The news that couch potatoes have been longing to hear comes from a research project conducted by Dr Gareth Davison and Dr Ciara Hughes of the School of Applied Medical Sciences and Sports Studies at the University of Ulster's Jordanstown campus.
The scientists have found that unaccustomed exhaustive aerobic exercise - which involves taking the heart rate to approximately 85% of its maximum for more than 10 minutes - releases dangerous free radicals that can adversely affect normal biological function in unfit individuals.
The only people who should push their bodies to this level of exercise on a regular basis are trained athletes, as these individuals seem to be protected from any adverse effects, according to Dr Davison. Unfit or individuals who exercise sporadically can cause serious chemical damage to their bodies.
"Our results highlight that you must 'eat healthy' at all times and ensure you have a proper intake of vitamins if you are involved in high-intensity exercise," said researcher Dr Ciara Hughes.
"If you are into high intensity exercise, you should work your way up to it and not simply just plunge in."
The research team used two groups of volunteers, giving one group a mixture of antioxidants, and the other a placebo. After a week of taking the tablets, the groups were put through their paces on a treadmill and went through routine medical tests.
Blood analysis revealed that the exhaustive aerobic exercise caused damage to important DNA and lipid molecules.
"Cellular damage was induced by the exercise. But we found that the group who were on the antioxidants had been protected to some extent," said Dr Davison.
"Natural antioxidants can be found in a balanced diet consisting of foods such as broccoli, spinach and berries. A key lesson is: if you are involved in strenuous aerobic exercise, make sure your diet is rich in antioxidants -- because they will protect against damaging your health.
But Dr Davison warns that the team's work should not be used as an excuse to take no exercise at all. There is a wealth of evidence that shows that exercise of a moderate intensity is protective against many chronic diseases.
The researchers will submit their work to a top scientific journal in the summer.