RSI, Repetitive Strain Injury, Does anybody have this problem while riding, i get it in my left hand when i brake, when i ride hard for a while using the back brake alot, my strength in my index finger just gives way and it cant brake sometimes slipping etc, i had it happen at edge of a highish drop and nearly went over handlebars, its f**king dodgy, does anybody have a similar problem?does anybody know how to prevent it?