It's not the kind of workout that you would expect to become fashionable, yet New Yorkers are flocking to the first gym dedicated to pelvic floor fitness. At the Phit - short for pelvic health integrated techniques - Spa in Manhattan, a team of gynaecologists aims to get people fit “from the inside out” by teaching them to exercise the “hammock” of muscles, nerves and ligaments that form a sling across the opening of the pelvis.

A strong pelvic floor holds up the bladder, uterus, bowel and rectum, allowing them to function optimally. But with age and stress from childbirth, excessive lifting of heavy weights and inappropriate exercise regimes, they tend to weaken. A study of 4,000 women, funded by the US National Institutes of Health, found that about one person in three had pelvic floor disorders, such as incontinence or dropped muscles, suggesting that the problem is more widespread than thought.

Daily exercises to strengthen the pelvic floor muscles can help to prevent many of these problems. And it's not just women who could benefit. Research has shown that men who maintain the muscle tone and function of their pelvic floor with a regular workout can avoid sexual problems such as impotence. Here's how:

1. Locate your pelvic floor muscles: they are the ones used to stop the flow of urine.

2. Kegals: sitting or standing, contract your pelvic floor muscles. Be careful not to flex the muscles in your abdomen, thighs or buttocks and do not hold your breath. Try to stay relaxed. Hold for three seconds, then repeat ten times.

3. The pelvic elevator: sitting on a chair with back straight, breathe in deeply. As you breathe out, contract your pelvic floor muscles and visualise a lift travelling up four floors. At each floor, contract your muscles a little more until you reach maximum contraction at the fourth floor. Hold the contraction, then slowly release the tension as you visualise the lift returning to the ground. Repeat ten times.

4. Four-point kneel: get on all fours with your hands beneath your shoulders and knees beneath your hips. Breathe in and, as you breathe out, contract your pelvic floor muscles and hollow the abdominal muscles towards your spine. Do not move your back. Hold for 20 seconds. Repeat ten times.

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