Hemodynamic responses and functional aerobic capacity in adults: insights from NASA method estimated VO₂

Introduction: Cardiorespiratory fitness, expressed as VO₂max, is a key indicator of cardiovascular and pulmonary health. Field-based tests such as the Sit-to-Stand (STS) and Two-Minute Step Test (2MST) provide accessible alternatives for evaluating functional capacity in rehabilitation settings. This study evaluated hemodynamic responses and estimated aerobic capacity from these functional tests and explored their associations using the NASA non-exercise VO₂max equation. Materials and methods: A cross-sectional correlational study (2023-2024) was conducted in healthy adults from Cali and Bogotá, Colombia, under STROBE guidelines. Participants completed the International Physical Activity Questionnaire (IPAQ), three Sit-to-Stand variants (5-repetition, 30-second, and 1-minute), and the 2MST. Heart rate, blood pressure, oxygen saturation, and perceived exertion were recorded before and after each test, along with recovery at 1 and 2 minutes. The Hemodynamic Gain Index (HGI) was calculated, and VO₂max was estimated using the NASA formula. The 2MST and 1-min STS produced the highest HGI and exertion levels. VO₂max correlated negatively with age and BMI and positively with height and functional performance, especially the 30-s STS. HGI showed modest correlations with VO₂ estimates in STS tests (r = 0.21-0.28). Conclusion: The 2MST elicited stronger hemodynamic responses, while STS variants were more closely associated with estimated VO₂max, supporting their combined use for efficient assessment of functional capacity, which is relevant for monitoring and guiding rehabilitation programs.