Background Paragraph: Athletics are very competitive these days at all levels, from school sports to the pros. Everybody is looking for that edge that will make them faster, stronger, more physically fit. One approach taken by many athletes is the use of amino acid supplements. The theory is that the increase in amino acids in the diet will lead to increased protein for muscles. However, the only real benefit comes to the people who make and sell the pills. Studies have not showed any advantage obtained by the athletes themselves. You’re much better off just maintaining a healthy diet. 
Story: A big marathon is being held in Chicago this year, Many people from the area are going to participate and there is a cash prize of $10000 for the winner. A sporting goods store that specializes in amino acid supplements  begins advertising more heavily during the time coming up to the race.
Given most of the marathon participants are competitive athletes, will sales at the sporting goods store increase or decrease for amino acid supplements?