Stretching helps the muscle work more efficiently the more expansion,more the contraction It gives the muscle the ability to take on board more fuel eg the more you blow a ballon up and let it go the further it will go,through released energy. Plus it opens up the energys pathways lactic acid is removed qiucker It has the ability to cope with shock and impact far better.So you have far less chance of getting injured Less injurys more time to get fit without worry Gut I hate personal trainers more than you to me their a load ponces ITrained amatuers for 27 years for nothing except enjoyment and havent read mens fitness for 30 years regards