# VO2MAX, 6-minute walk, and muscle strength each correlate with frailty in US veterans

## TL;DR

This study finds that cardiorespiratory fitness, walking ability, and muscle strength are linked to frailty in older US veterans, with VO2max showing the strongest correlations.

## Contribution

The study identifies VO2max, 6-minute walk, and arm strength as potential clinical indicators of frailty in veterans.

## Key findings

- VO2max negatively correlates with frailty scores and positively with physical performance and quality of life.
- The 6-minute walk test correlates with VO2max and physical performance but not strongly with frailty.
- Inflammatory biomarkers did not differ significantly between frail and non-frail participants.

## Abstract

Frailty often manifests as an increased vulnerability to adverse outcomes, and detecting frailty is useful for informed healthcare decisions. Veterans are at higher risk for developing frailty and at younger ages. The goal of this study was to investigate approaches in Veterans that can better inform the physiologic underpinnings of frailty, including maximal oxygen uptake (VO2max), 6-min walk, muscle strength, and inflammatory biomarkers.

Participants (N = 42) were recruited from the Buffalo VA Medical Center. Inclusion criteria: ages 60–85, male or female, any race, and not having significant comorbidities or cognitive impairment. Outcome measures included: the Fried frailty phenotype, the short physical performance battery (SPPB), quality of life (QOL) using the Q-LES-Q-SF, and the following physiologic assessments: VO2max assessment on an upright stationary bicycle, 6-min walk, and arm and leg strength. Additionally, inflammatory biomarkers (C-reactive protein, IL-6, IL-10, interferon-γ, and TNF-α) were measured using ELLA single and multiplex ELISA.

Participants: 70.3 ± 7.4 years of age: 34 males and 8 females, BMI = 30.7 ± 5.4 kg/m2, 26 white and 16 African American. A total of 18 (42.8%) were non-frail, 20 (47.6%) were pre-frail, and 4 (9.5%) were frail. VO2max negatively correlated with Fried frailty scores (r = −0.40, p = 0.03, N = 30), and positively correlated with SPPB scores (r = 0.50, p = 0.005), and QOL (r = 0.40, p = 0.03). The 6-min walk test also significantly correlated with VO2max (r = 0.57, p = 0.001, N = 42) and SPPB (r = 0.55, p = 0.0006), but did not quite reach a significant association with frailty (r = −0.28, p = 0.07). Arm strength negatively correlated with frailty (r = −0.47, p = 0.02, N = 26), but not other parameters. Inflammatory profiles did not differ between non-frail and pre-frail/frail participants.

Objectively measured cardiorespiratory fitness was associated with important functional outcomes including physical performance, QOL, and frailty in this group of older Veterans. Furthermore, the 6-min walk test correlated with VO2max and SPPB, but more validation is necessary to confirm sensitivity for frailty. Arm strength may also be an important indicator of frailty, however the relationship to other indicators of physical performance is unclear.