Cologne, Germany  - Exercise and weight training after a serious illness such as a heart attack or cancer is often recommended as part of recovery therapy even when the patient is old or not athletic.

Though it can't entirely replace medicine, it can result in the need for smaller dosages.

"All people who have had a tumour profit from physical activity," said Freerk Baumann of a research institute in Germany's sports college in Cologne dedicated to circulation and sports medicine. Activity can reduce fears and restore confidence in one's physical condition, he added.

In addition to the effects on the body, physical activity appears to have an impact on the development of a tumour. There is, however, no evidence that activity influences an existing tumour. There is evidence in patients who have had breast, colon and prostate cancer that the chances of a tumour reappearing are reduced by exercise, said Baumann.

There are theories that activity reduces particular hormones such as oestrogen and insulin. It is believed that these hormones have an influence on the growth of particular tumours. They are like nutrition for tumours, said Baumann.

In patients who have had heart and circulation disease, research indicates the positive effect of physical activity. In a study conducted at the University of Leipzig, a team led by Professor Rainer Hambrecht showed that people with a minor type of cardiovascular illness who used physical activity in their recovery did just as well as people who relied on common treatments such as stents or angioplasty.

According to Hambrecht, physical activity can increase the level of HDL cholesterol - known as the "good" cholesterol because it has a protective effect on the cardiovascular system. Blood pressure is also positively influenced by physical activity. Researchers say intensive sport leads to an improvement in the vascular function.

"The flexibility of the vascular system in general is better," said Hambrecht.

Claudia Walther, a top cardiologist at the heart centre in Leipzig, added that people who suffer angina also can reduce their symptoms by exercising, and it's long been known that physical activity reduces the chance of a heart attack. But occasionally taking a walk is not enough physical activity to achieve these all these positive effects.

"You must raise the pulse for 30 minutes," said Walther, adding that this should occur on a minimum of five days per week. Before starting, a stress EKG is recommended to determine the target pulse.

Endurance sports such as cycling and jogging are especially good for the heart, said Hambrecht. Walking is also recommended if it raises the pulse for a sustained period. Doctors caution patients about swimming because it is easier to overdo it.

In cancer patients the physical activity selected must be tailored to the type of cancer, said Baumann. Physical activity in water is especially good for breast cancer patients, for example, but it's not the best option for people who've had leukaemia or for men who have just had their prostate removed.

Patients should remember that it takes three to six weeks to notice any improvement, but people who stick with their physical activity programme will be rewarded, said Hambrecht. (dpa)