First there was sport. Then came jogging and aerobics. Now, with the popularity of Strictly Come Dancing and the news that the Department of Health is sponsoring schemes to help the nation lose weight, dance has joined the exercise mainstream. This is not surprising when you consider that a 10st 7lb person can burn 3.5 calories a minute by ballroom dancing - so 45 minutes would get rid of half a chocolate bar. But not all dances offer the same workout. To find out which style was best for whom, I spoke to Sharon Morrison, an independent physiotherapist specialising in sport and dance medicine, and Darren Bennett, British Latin champion, who is partnering Emma Bunton on Strictly Come Dancing.

Morrison sounds a note of caution at the beginning. "With all forms of dance, and any new activity, there's always risk," she says. "You've got to go at your own pace, listen to your body, and it should be under supervision." Nevertheless, she says it should be "an achievable form of exercise for most people."

Ballet

The most refined style of dance is "very good for stretching muscles and lengthening the body," says Bennett. Does this mean it could make you taller? No, but "It helps you reach your natural height."

For all its virtues, ballet does not provide a complete workout. "It's more an anaerobic activity," says Morrison.

Ballet is also difficult. Very difficult. "You're working on extreme ranges of motion and impact," Morrison explains. "I would always advise you to go into a class of your ability. Go with your appropriate level of fitness."

Waltz

"A waltz would be quite an easygoing type of fitness," says Bennett. "It's probably the least physical of the ballroom dances, and more socially orientated. Often, it would be the first thing you would do in a beginner class."

Such low-intensity dancing has its benefits, though. A study presented to the American Heart Association suggested that recovering cardiac patients benefited more from waltzing than from using a treadmill or an exercise bike.

"Ballroom dancing is especially good for the older generation," agrees Morrison, "and it's safe."

Salsa

One of the most popular forms of dance, salsa is "more physical than a waltz, but achievable at any age", according to Bennett. "It involves the arms, so you're giving the whole body a warm-up and a workout." Half an hour of salsa is said to burn around 250 calories, which is less than jogging, but still worthwhile. I ask Morrison if this makes it a good dance to lose weight with. "Absolutely, although you need that extra bit of range of motion," she says, adding that the dance is "good for the back and lower limbs".

Line dancing

"Good for coordination" is Morrison's opinion. Considering the violent boots, tassels and check shirts often involved, this presumably does not refer to colour coordination. "And you get a reasonable effect on your cardio- pulmonary system," she adds.

Line dancing can burn 200 calories in half an hour, making it a reasonable workout. It can also be done more or less energetically, depending on the class. "You can have opposite extremes for line dancing," says Bennett. "But you should be looking at graduating from it."

Belly

An extremely specific form of exercise. "It's good for maintaining the core [lower back muscles]," says Morrison. "I wouldn't advise people with back pain to go and do that straight off, though. It's something they should work up to."

"It's good for the legs, and good for the centre," says Bennett. "But it involves isolation. Using different parts of the body would definitely get more of a workout."

Break

If you keep it up for 30 minutes, breakdancing burns around 300 calories. However, this is not the dance to try if you're out of shape. "It's something you have to get fit to do," says Morrison. "It tends to be for younger people."

"Breakdancing is very hard," agrees Bennett. "From a fitness point of view, street dancing is good, whereas breakdancing is more specific, doing headspins and things like that. You'd have to have a very good centre [the stomach muscles along the front]."

Morris

This historic form offers a more sedate option for older men who prefer their dance floors woman-free. "It's not something I'm qualified in," says Bennett, "but there is a physical aspect to all styles of dance." Few, however, employ handkerchiefs and tobacco pipes.