If you don't like dancing around in a leotard, this is the class for you. It's basically a form of choreographed weight lifting. Using a solid tube to which you add weights, you work every part of the body in a series of moves taught by the instructor and set to music, with one song per body part - "Which means that after a while you begin to associate Tom Jones with extreme pain in your inner thigh," says Maria Meadows, health and fitness manager at Springs Hydro health spa in Leicestershire. The average 40-minute class burns around 250-400 calories but its main focus is toning.
5 It works fast. You'll start to see changes in your body shape within six weeks.
5 You can eat more. The main point of Body Pump is to increase muscle size and muscle burns. calories while you sit still (which fat doesn't). The more muscle you have, the more you can eat without gaining weight.
5 It's good for men - they like the weights and the fact that there's no dancing, not even in the warm up.
5 Because of the way teachers are trained - they learn one regime which they teach to one tape - it can get boring.
5 You'll need to do some cardiovascular work as well because although Body Pump is great for strength it won't increase your cardiovascular fitness in the way an activity like spinning will. Run, cycle or step twice a week.
Find your local body pump class (tel: 0990 133434).
This cycling class is the fitness trend of the decade, with hundreds of gyms in the UK offering classes and a number of alternatives springing up (look out for Cycle Reebok and RPM). "The appeal is that pretty much anyone can do it," says personal trainer Luke Wilkins. Described as part Tour de France, part yoga and part 12th-century torture chamber, it's not a workout for the fainthearted. Sitting on a specially modified exercise bike that allows you to reach intense speeds and alter resistance to simulate hills, you are led by the instructor through a 40-minute bike ride. You'll burn fat, tone your lower body and, to some extent, sculpt your arms. Normally the music's fast and loud and some classes go as far as turning down the lights. "You sweat, you focus - and you move your legs as fast as humanly possible," says Luke.
5 No co-ordination is required.
5 It's a workout for people with no time. Spinners burn 71/2-19 calories a minute, making a 40-minute class equivalent to an hour of fairly fast running.
5 It works your body in different ways. It trains for endurance and sprints, tones muscles and tests your cardiovascular system.
5 This is not a workout for absolute beginners. Heart rates of spinners reach up to 96 per cent of maximum and on a test of perceived exertion it rated 18-19 out of 20. This is a class to build up to.
5 US experts say that many spinners work too hard. Instead of listening to their own bodies they get caught up in the frenzy of the class and pay for it with back and knee injuries.
5 Spinner's butt. If you're going to spin regularly, buy some padded bike shorts.
Many gyms now offer spinning classes but you can also contact Cycle Reebok (tel: 0113 2371100) or RPM (tel: 0990 133434).
Yoga was the exercise Madonna claimed sculpted her headline-making biceps late last year. "Ashtanga is a series of breath-synchronised movements to purify the body and mind," says teacher Robin Catto. "In a group class you'll be led through a series of standing and sitting postures that stretch and strengthen the muscles and that are linked to the rhythm of your breathing. The result is an intense heat inside the body which causes it to shed toxins." The movements in ashtanga are fluid and carried out almost as one long movement. "There's no stopping for a chat. It's `move, breathe, move' for as long as the class lasts," says Robin.
5 A fundamental aim of yoga is to focus the mind. It will help you relax as well as tone your muscles.
5 You don't need to be flexible to do it: ashtanga comes in six levels (only two people in the world have completed number six) and each level has a set series of postures. Many group classes leave out the really tricky stuff, making it easier to learn.
5 You will end up pretty bendy. As well as strengthening muscles, you will stretch them, leading to improved flexibility.
5 As you practice, your metabolism revs up and you'll sweat disproportionately to the amount of effort you believe you're putting in.
5 You could get a headache: the idea of ashtanga is purification, so an intense session could lead
to detox symptoms.
Robin and Emma Chatto teach in the London area (tel: 0171 916 2510. To find other ashtanga teachers check out www.yoga.co.uk.
Ballet workouts (above) started when the New York City ballet devised a series of workout classes and the idea is to strengthen the spirit as much as the body. "While working in a ballet class may define and lengthen the muscles and give you a bottom you wouldn't believe, it's as much a workout for your mind," says Rebecca Paris, who runs classes at Forest Mere health farm in Hampshire. The reason is that during a ballet class you're taught to focus on every part of the body, determine what feels right and isolate exactly which muscles are working. This takes extreme concentration which means external worries can't intrude - your mind gets a break. You'll also end up standing like a dancer. "This class really does teach good posture. People walk out standing straight, which knocks about half a stone off the look of the average body," says Paris.
5 You'll get intense muscle definition. As Paris says, "Have you ever seen a ballerina's back? It's like a map of tiny muscles."
5 People of any age, any size, can take part with little risk of injury.
5 Co-ordination and balance: you need both for this class.
5 It doesn't burn many calories or work the cardiovascular system too hard.
5 It's not a widely available - class - you'll have to hunt around.
There is no centralised number for ballet workouts in the UK. Check your local dance studio. You could also order `The New York City Ballet Workout' (William Morrow and Company) which offers moves to do at home.
If a gym doesn't organise some kind of kickboxing in the US, people cancel their membership. The craze started because of Billy Blank's tae bo workout, a system involving boxing and dance moves. As yet, official tae bo classes are not available here - but kickboxing comes a close second in terms of its benefits - "stamina, incredible strength, toned arms and legs - fast reflexes - and knowledge that could protect you in the future," says Luke Wilkins. In a class you'll do a mix of cardiovascular work including sprinting, jumping and skipping on the spot, and then work on punching, kicking and sparring moves.
5 It's fun. One of the biggest reasons people drop out of exercise classes is boredom.
5 Kickboxers maintain their heartrate at around 75-85 per cent of maximum - the perfect rate for increasing lung and heart fitness.
5 While cardio-kickboxing isn't taught as self defence, it does teach you moves that could help you avoid injury.
5 The average class burns only 350-450 calories per hour.
5 If you're a novice, the sudden moves used in punching and kicking could lead to knee or elbow injuries.
There is no centralised number for kickboxing classes. Call your local gym or try the Sports Council.