Author(s): OPAZO, E., ANDRADE-MAYORGA, O., SOTO, F., LAVADO, A., CONTRERAS, F., LANG-TAPIA, M., ACEITUNO-PINTO, H., ROULIEZ, K., SERON, P., Institution: UNIVERSIDAD DE CÁDIZ, Country: SPAIN, Abstract-ID: 1263

INTRODUCTION:
The 6-minute walk test (6MWT) is widely used to assess functional capacity in individuals with heart failure (HF). However, its intensity compared to maximal cardiopulmonary exercise testing (CPET) remains controversial. The physiological threshold concept also requires the relative position intensity for proper exercise prescription. Identifying the intensity of the 6MWT in HF patients could enhance its utility for exercise prescription. This preliminary analysis explores the intensity of the 6MWT concerning physiological thresholds.
METHODS:
A preliminary cohort from the CO-CREATION-HF study (33 individuals, 25M/8W, age 67.1±11.8, BMI 29.9±4.9, NYHA II-III) was assessed. The 6MWT recorded heart rate (HR), breathing rate (BR), and distance. The day after next, a 6-10W/min incremental ramp test (60 rpm, cycle ergometer) determined maximal HR, BR, and VO₂. Shapiro-Wilk normality tests, Pearson correlation, and one-way ANOVA analyzed relationships and differences in 6MWT distance, HRmax, and BRmax (95% significance) with respect to physiological thresholds from CPET.
RESULTS:
During the 6MWT, HRmax expressed as a percentage of threshold values was 109.1% ±20.9 (VT1), 94.1% ±18.3 (VT2), and 79.43% ±13.0 (VO₂max). During the 6MWT, BRmax was 106.3% ±25.5 (VT1), 89.4% ±20.6 (VT2), and 69.1% ±18.4 (VO₂max). A significant correlation was found between 6MWT distance and VO₂max (r=0.53, p=0.02). Distance in the 6MWT correlated with %BRmax of 6MWT normalized to VO₂max BR (r=-0.33, p=0.34) but not with VT1 or VT2 BR. HRmax in the 6MWT was not significantly different from HR at VT1 or VT2 but was significantly lower than VO₂max HR. BR at VT2 and VO₂max significantly differed from 6MWT BRmax, whereas VT1 BR showed no difference.
CONCLUSION:
The 6MWT intensity, based on HR, falls between VT1 and VT2 but is significantly lower than VO₂max HR. Regarding BR, the 6MWT BRmax is only comparable to VT1 and significantly lower than BR at VT2 and VO₂max.
There were no differences in the distance achieved and the intensity relative to physiological thresholds in the 6MWT. These findings suggest that the 6MWT intensity aligns more closely with VT1 in individuals with NYHA II-III HF, supporting its use as a moderate-intensity exercise prescription tool.