Cardiopulmonary Exercise Testing (CPET)
Cardiopulmonary exercise testing measures breathing, oxygen use and heart rhythm while a patient pedals or walks against rising resistance, giving an objective picture of fitness and surgical risk.
Plain English
Patient-Friendly Explanation
A CPET is an exercise test with a mask over the mouth and nose. You pedal a stationary bike or walk on a treadmill while the resistance rises gently, and the machine measures how much oxygen you breathe in and how much carbon dioxide you breathe out. It shows how efficiently your heart, lungs and muscles work together, at what point you become breathless and how fit you actually are, even if you cannot manage much on the day. It is often done before weight-loss surgery.
Medical
Clinical Definition
Cardiopulmonary exercise testing provides breath-by-breath measurement of oxygen consumption, carbon dioxide production, minute ventilation and derived variables including peak oxygen uptake, anaerobic threshold, ventilatory efficiency as the VE/VCO2 slope, oxygen pulse and heart rate recovery. In obesity, peak oxygen uptake is conventionally indexed to lean body mass rather than total body weight, because fat mass inflates the denominator and underestimates functional capacity. The test is used in pre-bariatric surgical assessment to quantify functional capacity objectively and to unmask occult cardiac or pulmonary limitation, since self-reported exercise tolerance is unreliable and resting investigations are often normal. Ventilatory inefficiency, a low anaerobic threshold and chronotropic incompetence predict perioperative complications and prolonged length of stay, and the same test provides an individualised baseline for exercise prescription and for tracking training response after surgery.
Key Insight
Why It Matters
Subjective breathlessness is a poor predictor of surgical risk, whereas CPET replaces it with numbers, and those same numbers give the patient a realistic and motivating exercise target for after surgery.
Sources
Reviewed against standard medical references.
Medically reviewed by
Family Physician & Registered Acupuncturist, Accord Medical Clinic. MBBS (NUS), Graduate Diploma in Family Medicine (NUS), Graduate Diploma in Acupuncture (Singapore College of TCM).
Last reviewed: September 2026
This page is general health education, not medical advice. Whether any treatment is appropriate for you is a decision made in consultation after assessment.
