Quick Answer. In an officially-sanctioned MLB baseball game, there are 9 innings. If the home team is ahead in the top of the ninth and earns 3 outs, the game ends at 8 1/2 innings. If the game is tied after the away team earns 3 outs in the bottom of the ninth, the game goes into extra innings. Keep Learning.
When you exercise, the muscles you use require more energy. When exercise can be sustained, this demand is met primarily by aerobic means. Aerobic energy production in muscles results in increased gas exchange at the lungs, because more oxygen is taken in and more carbon dioxide is released.
Your muscles produce more energy when you exercise, and the circulatory system's activity during exercise enhances the supply of fluids, oxygen and nutrients your muscles need for energy production. Exercising also increases your body's rate of various chemical reactions. The circulatory system works hard in helping your body to balance and maintain healthy chemical concentrations during exercise. Regular physical activity helps increase the efficiency of the circulation system's activity during exercise.