Poor effort can be due to a variety of reasons such as orthopedic, neurological, depression, motivation and malingering.

CPET characteristics of patients that put forth poor effort include:¹

• 1. Low peak respiratory exchange ratio (peak RER < 1.00) indicating lack of development of significant metabolic acidosis
• 2. Low peak HR
• 3. Low peak O2-pulse (stroke volume)
• 4. Not attaining the anaerobic threshold
• 5. Systolic BP that does not increase more than 30 points
• 6. Possible manipulation of breathing patterns (such as hyperventilation)
• 7. Unremarkable pulmonary parameters (normal gas exchange and adequate breathing reserve at peak exercise)

CPET is an excellent tool for disability evaluations related to heart and lung disease. Patients that put forth poor effort are readily identified and poor peak VO2 in patients that put forth good effort proves impaired exercise capacity.