If you consider the example of tennis, landing your whole foot on the ground while playing a point, will waste a lot of time. There won’t be any spark in your movement and the opponent will tire you by making you run around the court. By the time you reach the last stages of the match, your body will wear down and leave you in a very bad shape.
Try to move around on the court with the help of your toes. Do not place your whole foot on the ground and bring some spark into your strides. You can accomplish this by building up your shin and calf muscles.
To maintain the same level of mobility on the court throughout the match will require a lot of stamina, one thing you can build up by pushing your body harder and increase its tolerance barriers. The more stamina you have, the better concentration you will have on every point. Otherwise you will lose your sense of direction during the match and will play half-hearted shots. The best players in the world are not only mentally strong but they are physically strong as well.
Your energy levels should be properly balanced while you are playing a match. For that you need to take in the right type and amount of fluids along with potassium supplements. Bananas, Gatorade, Lucozade and other energy drinks are good energy sources for players during a match.