Archive copy by Jenni Baden Howard

Derived from the Sanskrit word yug, meaning 'to yoke or harness', yoga refers to the union of mind and body. Although the mental and physical benefits of this Eastern practice have been enjoyed for thousands of years, new medical research suggests that yoga may be particularly beneficial for those with high blood pressure, diabetes, back pain and rheumatoid arthritis. Studies are also underway to determine its effect on various other conditions.

The latest adaptation of this ancient discipline is Power Yoga, championed by Beryl Bender Birch, American yoga teacher and author of Power Yoga The Total Strength And Flexibility Workout (Prion, £8.99). A highenergy workout comprising focused breathing and strong, fluid, seamless movements, Power Yoga is based on the ancient system of Ashtanga yoga, which dates back to before 200BC.

'In Power Yoga, you are training your body to build physical endurance in order to flow through the form without stopping,' explains Birch.'But, more importantly, you are training the mind to remain focused and to not break concentration.'

All the positions, or asanas, are linked in sequence by a connecting movement called a vinyasa, making for a nonstop workout that heats up the body. 'Not only do you have to warm up to stretch, you have to be warm while stretching,' says Birch. 'And not just warm, but hot and sweating.' This is accomplished by doing strength work concurrently and continuously with the stretch. Weights aren't needed, as muscles are worked and strengthened by using the body's natural resistance. Using the correct breathing technique through the nose helps, too. It warms the body faster and increases the power of the lungs.

Beginners to Power Yoga should work within their limitations. An approximation of the positions is sufficient for those who are new to the discipline. Avoid forcing your body into any position which feels uncomfortable. If you have a specific medical condition, or have recently undergone surgery, you are advised against certain Power Yoga moves (contraindications are listed in Birch's book). If in doubt, check with your doctor or physician before starting any exercise programme.

Each Power Yoga workout begins with Sun Salutations, a series of linked movements that will be familiar to those who already practise yoga. The The tadasana, or starting posture

Bring your feet together, big toes touching, with arms at your sides. Relax your shoulders and roll them backwards, pressing shoulder blades towards one another. Tuck your chin in slightly towards your chest and gaze straight ahead. Try not to focus on anything specific, just let your eyes relax.

Position 1

Inhale as you bring yourarms straight up over your head, placing your palms together just as you finish inhaling. Look up at your thumbs. Lift kneecaps by tightening or flexing thighs. Reach up as vigorously as possible, lengthening your torso and lifting your rib cage. Don't arch your back or lean backwards.

Position 2

Keeping legs as straight as possible, exhale as you bring your hands down in front of you. Place palms on the floor, alongside your feet, and tuck your head into your knees. Look towards your navel. Those with very tight hamstrings or lower back problems should bend their knees when trying this position.

Position 3

Look up, lifting your chest and extending your back as you inhale. Beginners should keep knees bent.

Position 4

Exhale as you walk your legs back. Make your body as stiff as a plank and slowly lower yourself to the floor into a pushup position. Keep elbows tucked in at the sides. Try to hold your body off the floor. If you cannot hold a pushup, put your knees down as you lower yourself to the floor. Look straight ahead of you.

Position 5

Point toes back so that your weight rests on the tops of your feet and palms only. Inhale as you arch your body back, bending from the waist. If this is too much work to begin with, or places too much pressure on the lower back or the tops of your feet, keep your knees on the floor. Look up and back towards the ceiling or wall behind you.

Be warned - this position will be extremely difficult for those with tight feet or ankles. It can also create lowerback distress it performed incorrectly. Do not allow your back to sag or shoulders to hunch up. When performed correctly, the lower back should not be uncomfortable.

Position 6

Exhale and turn toes back under, pushing up and walking hands back so that your body is in an inverted V position, bottom in the air. Feet should be parallel, about 10-12 inches apart, aligned with your hip bones. Hands should be about the same distance apart, lined up with your shoulderblades. Make sure palms are flat and fingers spread out evenly, and push down on heels. Look back towards your navel. Keep head relaxed. Tighten thighs and lift abdominals. Hold for a total of five breaths, in and out.

Position 7

Walk feet, one at a time, towards hands, while you inhale. Look up. Lift chest and extend back. Make sure your feet are together, big toes touching. Bend your knees only as much as necessary to get your hands on the floor, but don't squat.

Position 8

As you inhale, tuck your head into your knees and flex your back. If the backs of your legs are tight, bend your knees. Look at your navel.

Position 9

Inhale and come all the way back up to a standing position with your arms straight up over your head, palms together. Look up and lift your kneecaps by tightening or flexing your thigh muscles. Lift your rib cage, lengthen your torso and stretch up; imagine you're being drawn up to the ceiling by a string attached to your middle fingers and connected through your spine to a point between your feet.

Position 10

Exhale and then return to the starting position.

For more information about Power Yoga and Beryl Bender Birch's work, contact the Ashtanga Yoga Center in New York, tel (001 212) 6612895.