Plain water, which provides no energy to working muscles, does not stimulate the drive to drink, so the athlete may stop drinking before fully rehydrated. Another system affected is the respiratory system which has two main parts. As an athlete exercises his breathing rapidly increases, the heartbeat rate increases, and thus his endurance strengthens the circulatory and and respiratory systems. The third system affected is the digestive system. This includes the organs that physically and chemically change food into a form useful to the body.
Enzymes help change starches into sugars for energy.
After hard training by an athlete carbohydrates are used up. That's where sport drinks come in handy. There is no better way to replenish oneself for the next workout then by drinking liquid carbohydrates. Paper Cups 4. Stop Watch 5.