Though this list is not exhaustive, CPET can be useful in such instances as

• Evaluation of patients who have experienced an unexplained drop-off in their exercise capacity.
• Screening patients with certain risk factors prior to the initiation of a regular exercise program.
• Risk-stratification of patients -- The fitness level, or "VO_{2 MAX}" is a well-established predictor of cardiovascular mortality risk. 
• Establishment of optimal training zones in endurance athletes to minimize the risk of overtraining syndrome and optimize training gains.
• Evaluation of work capacity in individuals being considered for hire or in existing employees who have experienced a drop-off in work capacity.  This is well-suited towards employees in service occupations such as firefighting, law enforcement or the military.
• Exercise challenge testing for patients with known or suspected asthma
• Periodic monitoring of individuals with known progressive disease states (such as Cystic Fibrosis) to monitor changes in peak exercise capacity over time.