Cardiopulmonary Exercise Tests In People With Chronic Stroke

Peak oxygen consumption (VO2 peak), measured through cardiopulmonary exercise testing (CPET), is considered the gold standard to quantify a person’s cardiorespiratory fitness (CRF). CPET tests the multifaceted way in which the cardiorespiratory (CR), metabolic, musculoskeletal, and neurological systems interact to deliver and utilize oxygen during increased workloads. As studies of high intensity exercise in people with chronic stroke (PwS; > 6 months) have grown, CPET has been used to measure CRF in this population. PwS have VO2 peak values 53% of those found in age- and sex-matched controls, which likely plays a role in the presence of diminished mobility. Given significant neuromotor deficits experienced by PwS, peak performance may be impacted by neuromuscular factors. If the CR system is not the main limiting factor in CPET in PwS, the VO2 peak obtained may not accurately represent their CRF. PURPOSE: To characterize cardiorespiratory and metabolic responses to CPET in PwS. METHODS: PwS were included if their walking speed was 0.3-1.0 m/s and they walked <8000 steps/day. Participants underwent a maximal treadmill CPET with a 12-lead electrocardiogram and breath-by-breath analysis of oxygen consumption recording continuously. Treadmill speed was constant at 85% of the individual’s maximal treadmill speed. Participants first walked at 0% incline for 2 minutes, next at a 2% incline for 2 minutes, and then the incline increased by 2% each minute. Tests were terminated if biomechanical faults prevented participants from walking safely or per ACSM guidelines. RESULTS: 307 participants with chronic stroke (> 6 months; age (y) 63.1 + 12.7; 45.8% female, 40.6% on beta-blocker medication, BMI 30.5 + 6.3) completed a baseline CPET as part of a larger, multi-site randomized clinical trial (PROWALKS). Participants had an average resting VO2 of 2.7 + 0.96 mL/kg/min and VO2 peak of 11.8 + 5.2 mL/kg/min. Total exercise time was 4.9 + 2.7 minutes with a HRpeak of 125.8 + 21.4 beats/min (76% of age predicted HRmax) and RERpeak of 0.99 + 0.13. CPETs were ended for multiple reasons: a) self-selected stop (39.4%); b) clinician stopped due to BP or ECG (31.3%), or c) biomechanical faults (29.3%). CONCLUSION: Results suggest PwS rarely achieve ACSM criteria for a maximal test, indicating CPET results in PwS may not represent a true test of CRF.