I don't have a problem with children doing yoga, but it does strike me as odd. Yoga, in my limited understanding of the discipline, seems designed to fix things that kids, by and large, don't have wrong with them. Websites offering information about yoga for children talk about how it helps them increase their flexibility and cope with stress. One has this testimonial from a newly relaxed child called Daisy: "I feel like a pretty flower floating on the water." My children rarely complain about how stiff they are or how much stress they're under, and if they did I'd say, "Trust me. It gets much worse."
Yoga for kids is nevertheless big business. Triyoga in London has courses for children as young as five. Some of the junior yoga DVDs on offer target three-year-olds. As a babysitter, a friendly TV yoga instructor is probably preferable to the Pokémon Movie, but one wonders whether it's a good idea to teach children that this is how exercise is done. Perhaps they should just go out and play.
Still, I can't imagine it doing them any harm, and it seems as if I'm well behind the curve on this topic: when I raise the idea of doing yoga with my seven-year-old son Will, being careful not to mention that it will make him feel like a pretty flower floating on the water, he says he already does yoga. Really? "Used to," he says, on his way to the fridge. "At school. A person called Mrs Usher came and taught us." What did it consist of, exactly? "Learning these things like cat and dog moves. It was weird." He pauses to give me an impromptu demonstration of Downward Facing Dog, hands and feet on the floor, bum pointing at the ceiling. "Then you start barking like a dog," he says.
What is yoga for? I ask him. "Your body. So your backbone and your hip and your spine can move a lot. And it calms your mind down. And breathing. You won't be able to breathe properly if you don't do yoga."
I still don't believe that he will show any interest in it as an extra-curricular - or indeed, father-and-son - activity. I doubt he will think much of the kids' yoga kit I have ordered from Gaiam Direct - basically a DVD and a gym ball with a picture of Scooby Doo on it and the slogan "Doo Yoga". As a fitness regime, however, it manages to combine two of his favourite pastimes: lying on a big rubber ball and watching TV. I thought I might join in, but by the time I tracked down my own gym ball he felt he had conquered the techniques, and was reluctant to revisit past challenges, preferring to lie on the ball and watch Deal or No Deal instead.
It was another few days before I persuaded him to show me the ropes. The DVD features a creepily enthusiastic American woman as the guru and six kids on gym balls as our virtual ashram. There is no talk of chakras or prana or of achieving union with the divine by integration of mind, body and spirit; just a few cheery exhortations to sit up nice and straight.
"You start off on an exercise and then you do a game and then you go on the real yoga," says Will, who has more or less memorised the 30-minute session. We sit on the balls and follow along, stepping to the right, to the left, standing up, picking up the ball and throwing it in the air. I have over-inflated the Scooby Doo ball slightly; Will's feet barely touch the floor when he's sitting on it, and after the fourth time he rolls off across the room I have to pause the DVD to let some air out. It takes a while to get to what Will calls the "real yoga": hands on the floor in press-up position, feet on the ball. We are attempting to roll ourselves back and forth from ankles to knees and back again.
This is an exercise that I have done at the gym many times, although I have always slightly cheated (the trainer can't look everywhere at once), and as a result Will is much better at it than I am. "Just don't drop your hips," he says, echoing the woman on the DVD. Then we lie back with our heads on the ball and our feet on the floor. "This is really hard," he says.
I had worried that my son might be a bit young for indoctrination into the mysteries of this ancient discipline, but halfway through the DVD I'm beginning to wonder if he's actually getting enough yoga with his workout. I want to tell him that there's a whole spiritual element that's not being addressed by this grinning woman.
When I ask him what he thinks of it, however, he shrugs his shoulders and says, "I liked it." I point out that, despite his use of the past tense, there is still about 10 minutes left to go on the DVD. He shrugs again, rolls forward slightly on the ball, pushes eject and deftly exchanges the disc for SpongeBob Squarepants: the Movie. His breathing slows. His lower jaw slackens gently and comes to rest on the ball. As does mine. And relax.