A recent report on athletes' preparation came to the conclusion that whether they warm up or not does not actually make much difference. Perhaps warming up is not physically essential, but, for athletes, it seems to be psychologically important, a sort of inventory of their powers. For musicians, the process clearly works on a number of levels but, as with athletes, it's not at all clear how preparation has a direct effect on the performance itself. After all, the performance is as much mental as physical. Does the ritual help to keep thoughts in, or help to keep them out?

When I was a violinist in the National Youth Orchestra, every rehearsal and every concert was famously preceded by a two-minute silence. Having tuned the instruments, we all sat quietly until the arrival of the conductor. I rather liked this enforced silence before an intense burst of music. For me, whatever sound came next was more meaningful if it emerged from a still background. However, for many of my string-playing friends, the silence was torture. They resented the interruption to that physical bonding process with their instruments, feeling that they would have to start all over again when the performance began.

How musicians psych themselves up for performance has fascinated me ever since. Some like to prepare months ahead of the concert, whereas others deliberately leave preparation almost too late, to generate more adrenaline. Some like to be left in peace to assemble their thoughts before a concert, while others practise right up to the last minute. Indeed, many are still practising while standing outside the door to the platform. Only seconds of silence separate their off-stage practice from their on-stage performance. They seek to create a continuum of sound in which the concert is only the last and most vivid segment. This applies particularly to string players, who seem to bond with their instruments more than other musicians do, perhaps because of the strong tactile elements of playing a violin or cello.

Silence before concerts is often imposed on pianists because there is no piano backstage. As a pianist and chamber musician, therefore, I'm often forced to sit quietly and watch other people preparing for the concert. Mostly, they practise the difficult bits. They play them over and over, trying to nail the tricky fingering into their subconscious, so that under the strain of platform nerves, the patterns will remain. However, the effect of repeating difficult passages is by no means calculable. A statistician once told me that obsessive practice may actually lessen the chances of success on stage. A player feels that the more often he or she can correctly repeat a difficult passage backstage, the more certain it is to be right in the performance. From a statistical point of view, however, a run of "perfect sixes" actually increases the chance of something different happening next time. Twenty repetitions in the dressing-room actually makes it more likely that the 21st - which occurs on stage - will fail. This may be a mathematical truth, but most musicians would balk at it.

Many players feel they have to concentrate intensely to get difficult things right in performance. If you could get inside their consciousness you would feel the outside world fading away every time there was something challenging to play. Such an approach seemed normal to me, too, until I watched the Hungarian pianist Gyorgy Sebok demonstrating to students that concentration isn't always the answer. He believed that if you had done the necessary practice, it would actually help to de-focus at the relevant moment. It was funny and instructive to see him deliberately distract a student while they were playing something terribly hard. If he intervened at the right moment, they would look up in surprise while their hands, unhampered by the mind, whizzed effortlessly through the difficult bits.

He had similar results when he asked someone to concentrate on one hand while the other was playing something hard. Assuming that the student had worked out the fingering, it worked like magic to let the hand find its own way without conscious supervision. Concentration was clearly a mixed blessing, and could even create problems. There were other parts of the mind and body that knew what they were doing. "Think nine times and play once," said Sebok.

This extends beyond the concert platform. Music conservatories are full of people who think that the more they practise, the better they will be. To impress their teachers, students set themselves arduous practice goals. I know students who start practising at 7am, grab a coffee at 10am before classes begin, and practise again in the evenings. Not many discover how to practise productively, and most people spend long periods "practising" what they can already play. A college health adviser recently told me that his days were full of students seeking advice about their aching backs, shoulders and hands. Yet if they did more practice away from the instrument, focusing on the mental instead of the physical, they would benefit enormously.

For some, however, it is essential to interpose some peaceful time between rehearsal and concert. They like to think about the whole shape of pieces, or if they are about to play from memory, to run through things in their head quietly. Some like to distract themselves by reading a book or chatting. I like to go and wait at the side of the stage where I can hear the murmur of the audience and get a sense of their mood. For me, the relationship with the piano is secondary to what I hope to do as a musician. My focus is on the music and on communication of it to the audience. I need to play the piano to achieve this, but playing the piano isn't the sine qua non of my musical life. Perhaps performers of my temperament hope to create in themselves an appetite for the music by holding it at arm's length for a while. We are aware of the audience sitting in silence waiting for the music to begin. If the artist sits on the other side of the curtain in silence too, the music may come as a gift to audience and artist alike.

A fan of the distinguished German pianist Wilhelm Kempff once asked him: "How come you never play any wrong notes?" Kempff replied: "I only practise the right notes." When I heard this story, I immediately had a sense of all the time that we spend, in effect, practising the wrong notes: thinking the wrong thoughts, doubting our ability to get it right, watching ourselves for failures of nerve. Kempff's approach seemed to indicate a mind at peace with itself. To practise "only the right notes", and only in the right way, would eliminate whole areas of unproductive work of the kind that occupies practice rooms in colleges and concert halls throughout the world.

© Susan Tomes