Biking, running and walking are all good for you. But the strain can be tough if you're overweight, have arthritis or suffer from other joint problems or injuries. What to do? Just add water.

A study presented today at the Canadian Cardiovascular Congress found that people who used an immersible ergocycle - basically an exercise bike in a pool - had just about the equivalent workout to using a typical stationary bike.

"If you can't train on land, you can train in the water and have the same benefits in terms of improving aerobic fitness," says Dr. Martin Juneau, director of prevention at the Montreal Heart Institute.

He says people might assume that exercising in the water can't be as valuable as exercising on land. Because of the resistance of the water when you move, it doesn't seem like you can work as hard. This new study indicates otherwise.

Healthy participants did exercise tests on both the land and water cycling machines (with water up to chest level). They increased their intensity minute by minute until exhaustion.

Dr. Juneau reports that the maximal oxygen consumption - which tells you whether it was a good workout - was almost the same using both types of cycles.

His study colleague Dr. Mathieu Gayda, a clinical exercise physiologist at the Montreal Heart Institute, adds: "Exercise during water immersion may be even more efficient from a cardiorespiratory standpoint."

Another finding, says Dr. Juneau, is that the heart rate of the participants was a little lower in the water.

"You pump more blood for each beat, so don't need as many heartbeats, because the pressure of the water on your legs and lower body makes the blood return more effectively to the heart. That's interesting data that hasn't been studied thoroughly before," says Dr. Juneau.

Considering the number of people who can find it difficult to exercise on land, the water option is promising, says Dr. Juneau. He says that swimming may be the best exercise of all but not everyone can swim. With the workout benefits, the low stress of moving in the water and the reduced chance of injury, "this is a great alternative," he says.

Heart and Stroke Foundation spokesperson Dr. Beth Abramson notes that 85 per cent of Canadians do not accumulate the recommended 150 minutes per week of moderate- to vigorous-intensity physical activity.

"Inactive people who become physically active can reduce their risk of heart attack risk by 35 to 55 per cent, plus lower their chance of developing several other conditions, cut stress levels and increase energy," says Dr. Abramson. "Even if you have difficulty moving more, there are always solutions, as this study shows. This is encouraging given the aging population - it's never too late or too difficult to make a lifestyle change."