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

## TL;DR

This study explores how different physical tests relate to heart function and aerobic capacity in adults, using NASA's method to estimate VO₂max.

## Contribution

The study introduces a combined approach using NASA's VO₂max estimation and hemodynamic responses from functional tests to assess aerobic capacity.

## Key findings

- The 2MST and 1-min STS tests caused the strongest hemodynamic responses.
- VO₂max estimates correlated with functional performance, especially in the 30-s STS.
- HGI showed modest correlations with VO₂ estimates in STS tests.

## Abstract

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.

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.

A total of 260 adults participated. Hypertension (30.8%) and diabetes (23.8%) were the most frequent comorbidities. All tests increased heart rate and blood pressure significantly (p < 0.001), with the greatest responses in the 2MST and 1-min STS, while oxygen saturation remained stable. 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).

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.