It seems that when stress and anxiety are studied in terms of 'state' and 'trait' components, the resultant levels of arousal may diminish performance. In plain English, that means that when you're nervous you can't hit the ball. Nideffer apparently spent years measuring the skin arousal of swimmers before meets, comparing those measurements with ones taken on their best and worst days, before deciding that athletes can be hypnotized out of their bad habits and use TM to calm themselves further. Having confused his reader entirely with abstruse theories about relevant and irrelevant muscle tension (some of them relevant, most of them not), he leads one to the conclusion that if you read the book before an important athletic event, if may, indeed, make the difference between winning and losing. Your mind will be so numb there won't be room for nervousness to creep in.