Oh, how my back aches! Like most over-enthusiastic gardeners, I've overdone it on digging, weeding and planting during the fine days we've had in the last week. And I'm paying for it.

I know that they say an hour's hard graft in the garden is equivalent to a good session in the gym, but it can also put intense stress on the body.

You can burn 290 calories an hour weeding or 325 calories digging, but if you don't warm up properly and then over-exert yourself in spring after months of doing nothing in the garden, you're asking for trouble, says Jacqueline Knox, a Pilates expert and physiotherapist to the British rowing squad.

However she says there are ways to garden which can alleviate aches and pains. Knox has now teamed up with garden designer Bunny Guinness to write Garden Your Way To Health And Fitness, a book offering exercise plans and injury prevention in the garden.

One in 20 of Knox's clients at her clinic in Tallington, Lincolnshire, is seeking help for a gardening injury.

"I have found that making very small changes to their gardening technique and showing them how to do some therapeutic, strengthening exercise before gardening and some stretching afterwards, causes many of their aches and pains to melt away," she says.

She advocates Pilates-based movements and body balancing, keeping your spine in a neutral position (neither slouching nor arching) rather than slumped forward.

There are safe ways to carry out everyday tasks like pushing wheelbarrows, lifting heavy pots and picking low-lying fruit, she says, along with ways to alleviate backache, tennis elbow and other common gardening ailments.

When lifting heavy objects like potted plants, keep your back in a neutral position and take away the strain by bending your knees to go down for the object and then use your legs and abdominal muscles to lift it. Lift the pot with both hands, with one foot on the ground for stability, while the heel of the other foot can come off the ground as you rise to a standing position. If you have a bad back or problems with your knees or hips, get someone else to lift the object.

To prevent tennis elbow, choose a tool with a hand grip the right size for you, which helps to avoid gripping too hard and overclenching while carrying out repetitive movements.

When digging, rest or carry out a different activity every 15 minutes to lessen your vulnerability to strain.

Hand-weeding can be done by squatting, bending your knees and keeping your back in its neutral position. Avoid neck strain by keeping your shoulder blades down and in and using your shoulder blade muscles to weed.

Another option is to weed by kneeling on your hands and knees. Make sure you have something like a pad to kneel on and try to keep your back in its neutral position. Keep your shoulder blades down and in towards the middle of your back, with your elbows softly bent.

If you pick up watering cans from the ground, bend your knees and keep your back straight. Stand up straight, pulling your lower stomach upwards and inwards, relax your shoulders, keeping your shoulder blades pressed down into your back to minimise strain on your shoulders and neck. As you walk, keep your posture upright, keeping your stomach drawn up and in. That way, the weight will be taken on by your abdominal muscles and shoulder blades.

When weeding, deadheading or doing any other job which involves bending, avoid bending from the waist.

"Whenever you bend over in the garden, aim to keep your back as straight as possible while bending your knees," she advises.

When doing overhead work such as hedge-trimming, watering hanging baskets or pruning high trees, your neck becomes vulnerable to strain. In an ideal position the neck shouldn't be too far forward (with the chin sticking out), or too far back (hunched into the shoulders).

Using a small stepladder and long-handled loppers reduces the need to tilt your head back while pruning trees and tall shrubs.

Post-gardening stretches should also lessen stiffness after a day's work and are essential if you've been doing something involving leaning over or kneeling for long periods, such as weeding, she says.

  • Garden Your Way To Health And Fitness, by Bunny Guinness and Jacqueline Knox, is published by Timber Press, priced £14.99.