Abstract
Background: Peak oxygen uptake (V̇O2) is a critical prognostic indicator in heart failure (HF) and is influenced by skeletal muscle oxygen utilization. Muscle oxygen saturation (SmO2), assessed using near-infrared spectroscopy, reflects peripheral oxygenation capacity. Although higher leg muscle strength has been linked to greater peak V̇O2, its relationship with muscle oxygenation dynamics remains unclear.
Methods and Results: Twenty-six men (age 64±11 years) with HF were categorized into high (n=13) and low (n=13) strength groups based on median knee extension strength normalized to body weight (BW). Cardiopulmonary exercise testing (CPX) was performed while monitoring SmO2and total hemoglobin (THb) at the right vastus lateralis. Relative changes from rest to each exercise stage were calculated. A multivariable linear mixed-effects model evaluated the association between SmO2changes and knee extension strength, adjusting for age, log-transformed B-type natriuretic peptide (log-BNP), leg muscle mass, THb changes, and adipose tissue thickness (ATT). Log-BNP was lower in the high-strength group (P=0.001). SmO2reductions from rest to 40–100% peak V̇O2were greater in the high-strength group. Knee extension strength (β=0.9±0.4; P=0.016) and THb change (β=−5.6±1.5; P=0.001) predicted SmO2changes.
Conclusions: Higher leg muscle strength is associated with favorable muscle oxygenation dynamics during incremental exercise in HF, independent of blood volume dynamics.
