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.
Plasma epinephrine concentration increases during aerobic exercise in proportion to the intensity of the exercise. Anaerobic exercise provokes even greater concentration increases (see Metaboreflex). In the curve above, anaerobic metabolism probably contributed to the steep epinephrine increase seen at 200 Watts and above. Heart rates were 175 to 180 beats per minute at the most strenuous level of exercise. Plasma epinephrine concentration increases very rapidly at the beginning of exercise. But when exercise targets a specific workload, epinephrine increases even further, but less rapidly, over time, as shown below. The workload in this case was 67% of maximum O2 uptake.