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.
Maximal Heart Rate. Before you put away your workout shoes and slink back into bed, understand what the American College of Sports Medicine means by vigorous exercise. For an exercise to count as vigorous, it must raise your heart rate to at least 70 percent of your maximal heart rate. This is the point at which exercise transitions from moderate- to vigorous-intensity exercise according to the ACSM. It is also the moment when every drop of sweat means more to your heart.