Feasibility, Methodology, and Interpretation of Broad-Scale Assessment of Cardiorespiratory Fitness in a Large Community-Based Sample

Cardiorespiratory fitness (CRF) is intricately related to health status. The optimal approach for CRF quantification is through assessment of peak oxygen uptake (VO(2)), but such measurements have been largely confined to small referral populations. Here we describe protocols and methodological considerations for peak VO(2) assessment and determination of volitional effort in a large community-based sample. Maximum incremental ramp cycle ergometry cardiopulmonary exercise testing (CPET) was performed by Framingham Heart Study participants at a routine study visit (2016–2019). Of 3486 individuals presenting for a multi-component study visit, 3116 (89%) completed CPET. The sample was middle-aged (54±9 years), with 53% women, body mass index 28.3±5.6 kg/m(2), 48% with hypertension, 6% smokers, and 8% with diabetes. Exercise duration was 12.0±2.1 minutes (limits 3.7–20.5). No major cardiovascular events occurred. A total of 98%, 96%, 90%, 76%, and 57% of the sample reached peak respiratory exchange ratio (RER) values of ≥1.0, ≥1.05, ≥1.10, ≥1.15, and ≥1.20, respectively (mean peak RER=1.22±0.10). With rising peak RER values up to ≈1.10, steep changes were observed for percent predicted peak VO(2), VO(2) at the ventilatory threshold/peak VO(2), heart rate response, and Borg (subjective dyspnea) scores. More shallow changes for effort dependent CPET variables were observed with higher achieved RER values. In conclusion, measurement of peak VO(2) is feasible and safe in a large sample of middle-aged, community-dwelling individuals with heterogeneous cardiovascular risk profiles. Peak RER ≥1.10 was achievable by the majority of middle-aged adults and RER values beyond this threshold did not necessarily correspond to higher peak VO(2) values.