Purpose
The aim of this study was to examine the reliability and applicability of the \({\dot{\text{V}}}\) O2 and heart rate (HR) kinetics during moderate-intensity cycling in cancer patients receiving immunotherapy-checkpoint inhibitors (ICI) and healthy controls.
Methods
Patients receiving ICI therapy (n = 13, 46 ± 15 y, BMI = 24.3 ± 2.6) and age-matched controls (n = 13, 47 ± 18 y, BMI = 24.9 ± 4.5) completed all study procedures. Following medical clearance, they performed a ramp CPET on a cycle ergometer until task failure. During the second visit, they completed three consecutive step-transition tests: 6 min at 20 W, followed by 6 min at 90% of gas exchange threshold (GET), and continuing to 30-min constant-load cycling, with gas exchange and cardiovascular responses constantly monitored.
Results
The control group reached ~ 30% higher peak power output, resulting in higher peak values of minute ventilation ( \({\dot{\text{V}}}\) E by 23%), oxygen uptake ( \({\dot{\text{V}}}\) O2 by 33%), and carbon dioxide production ( \({\dot{\text{V}}}\) CO2, by 27%) compared to the ICI group. Similar HR max. and self-reported levels of perceived exertion (19 ± 1) were observed during CPET. The moderate-intensity τ \({\dot{\text{V}}}\) O2 showed good-to-excellent reliability for both groups (the interclass correlation coefficient ranged from 0.755 to 0.951), while the τHR had twofold higher coefficient of variation (CV%) in ICI patients compared to controls (24% vs 10%, p = 0.001). The Bland–Altman analysis revealed disproportional increase in HR during 30-min constant-load cycling in controls (14 ± 7 bpm−1) and ICI patients (17 ± 9 bpm−1), despite stabile \({\dot{\text{V}}}\) 02 and PO.
Conclusions
Apparently, the \({\dot{\text{V}}}\) O₂ kinetics offer a more reliable alternative to HR responses when prescribing exercise for ICI patients. Significant intra-individual variability in τHR may indicate early cardiovascular deconditioning, highlighting the need for more comprehensive diagnostics.
