Final answer:
The first step in the progressive exercise test to exhaustion in anaerobic threshold is the buildup of ATP and lactic acid levels.
Step-by-step explanation:
The first step in the progressive exercise test to exhaustion in anaerobic threshold is the buildup of ATP and lactic acid levels.
During anaerobic exercise, the intensity of the exercise determines the fuel source used for ATP production. As the exercise becomes more intense, the demand for ATP increases, leading to increased breakdown of glucose and the production of lactic acid.
This process occurs when the muscles are used close to their maximum contraction strength but for a relatively short period of time, consuming a small amount of oxygen.