How should we measure fitness in patients scheduled for knee and hip replacement surgery?

INTERVENTION: We will conduct a four‐arm crossover (within participants) study, measuring peak oxygen consumption across cycle, treadmill, cross‐trainer and arm ergometer modalities, in those with severe hip or knee osteoarthritis. Fifteen participants will be recruited to perform maximal, symptom‐limited exercise testing on each exercise modality utilising an incremental protocol. Participants will complete a 3‐5 minute warm‐up, before exercise intensity increases every 1‐2 minutes, until volitional fatigue or test termination; each exercise test takes approximately 8‐12 minutes (excluding warm‐up). The testing will be administered and supervised by a registered clinical exercise physiologist (with 12 years experience), who is also a university research student. Testing will be conducted at the Dunedin Public Hospital. Tests will be one‐on‐one sessions, separated by at least 4 days to ensure adequate washout between exercise tests. Participants will be reimbursed $5 per visit to cover travel expenses. CONDITION: Musculoskeletal ‐ Osteoarthritis Osteoarthritis; ; Osteoarthritis PRIMARY OUTCOME: Oxygen consumption, assessed via metabolic cart.[Peak exercise across all four exercise tests.] SECONDARY OUTCOME: Anaerobic threshold as a percentage of peak oxygen consumption, assessed via metabolic cart.[Across all four exercise tests] Diastolic blood pressure, assessed via aneroid sphygmomanometer.[Prior to initial exercise test and peak exercise across all four exercise tests] Heart rate as a percentage of predicted maximum heart rate, assessed via 12‐lead electrocardiogram and heart rate band.[Peak exercise across all four exercise tests] Heart rate, assessed via 12‐lead electrocardiogram and heart rate band.[Peak exercise across all four exercise tests] Maximal exercise test acceptability questionnaire [Post exercise test following all four exercise tests] Minute ventilation, assessed via metabolic cart.[Peak exercise across all four exercise tests] Oxygen consumption at the anaerobic threshold, assessed via metabolic cart.[Across all four exercise tests] Oxygen uptake efficiency slope, assessed via metabolic cart.[Across all four exercise tests] Pain score, assessed via Visual Analogue Scale.[Pre‐exercise and post‐exercise across all four exercise tests] Rating of percieved exertion, assessed via Borg Rating of Percieved Exertion scale.[Peak exercise across all four exercise tests] Respiratory exchange ratio, assessed via metabolic cart.[Peak exercise across all four exercise tests] Systolic blood pressure, assessed via aneroid sphygmomanometer.[Prior to initial exercise test and peak exercise across all four exercise tests] INCLUSION CRITERIA: ‐ Patient meets the threshold for elective arthroplasty at Dunedin Public Hospital or is expected to meet the threshold within the next year; ‐ Patient is able to travel to the study centre to complete all sessions.