Cardiopulmonary exercise testing with elastic resistance for determining ventilatory thresholds and maximal oxygen uptake in middle-aged adults

Objective: To investigate the physiological and perceptual responses to the cardiopulmonary exercise test with elastic resistance (CPxEL), using the traditional treadmill cardiopulmonary exercise test (CPx) as the standard reference. Methods: Twenty-seven physically active adults (57 ± 7 years; both sexes) performed two maximal cardiopulmonary exercise tests in randomized order, seven days apart: treadmill CPx and CPxEL involving back-and-forth movements against elastic resistance. Cardiorespiratory variables, heart rate, and ratings of perceived exertion (central and peripheral) were assessed. A verification phase was performed to confirm maximal physiological responses. Results: At the first ventilatory threshold (VT1), CPxEL showed higher oxygen uptake (VO2) (15.8 ± 3.0 vs 12.7 ± 3.3 ml kg−1·min−1; P = 0.02) and heart rate (HR) (115 ± 12 vs 105 ± 11 bpm; P = 0.01). At the second ventilatory threshold (VT2), peripheral effort was greater for CPxEL (Z = −2.38; P = 0.02). At maximal effort, the respiratory exchange ratio (RER) was higher in the CPx (P < 0.05), and peripheral exertion remained higher in CPxEL (Z = −1.97; P = 0.05). Conclusion: CPxEL is a feasible method for identifying ventilatory thresholds and VO2max, and may be applied to prescribing aerobic exercise with elastic resistance in middle-aged adults. However, it elicits distinct physiological and perceptual responses compared with the CPx and the two protocols should not be used interchangeably. Further studies are needed to confirm the accuracy and safety of CPxEL in different clinical populations.