Exercise intolerance in HFpEF is associated with increased intermuscular fat and impaired whole body and quadriceps muscle oxidative capacity, but because intermuscular fat was not associated with oxidative capacity measures, the two appear to affect exercise tolerance via different physiological mechanisms.
Lean thigh mass was similar between HFpEF patients and healthy older adults, but intermuscular fat percentage was significantly greater in HFpEF.
HFpEF patients had lower exercise tolerance and whole body aerobic capacity normalized to lean thigh mass than healthy older adults.
Quadriceps oxidative capacity was impaired in HFpEF, with a slower phosphocreatine recovery time constant.
Intermuscular fat percentage was associated with peak watts normalized to lean thigh mass and with whole body V̇o2peak normalized to body mass.
Intermuscular fat percentage was not associated with V̇o2peak normalized to lean thigh mass or with quadriceps τPCr.
V̇o2peak normalized to lean thigh mass and quadriceps τPCr were each associated with peak watts and with each other.
The authors conclude that exercise intolerance in HFpEF is associated with increased muscle steatosis and impaired whole body and quadriceps oxidative capacity, which act via distinct mechanisms.
This study compared 38 older adults with heart failure with preserved ejection fraction (HFpEF) to 17 healthy older adults of similar age. Participants did a cycling exercise test, and MRI-based methods were used to measure fat within the thigh muscle and how well the thigh muscle regenerates energy after exercise, a marker of its ability to use oxygen. The amount of thigh muscle was similar in both groups, but people with HFpEF had more fat within the muscle, lower exercise capacity relative to their muscle mass, and slower recovery of muscle energy stores, which suggests poorer muscle oxidative capacity. Both lower oxidative capacity and greater muscle fat were linked to poorer exercise performance. However, muscle fat was not related to the measures of oxidative capacity, which suggests the two problems may limit exercise through different pathways. This research suggests that exercise limitation in HFpEF involves problems in the skeletal muscles themselves, not just the heart, and that more than one muscle problem may be involved. The study was a cross-sectional comparison, so it shows associations rather than cause and effect. The HFpEF group also had a higher body mass index than the healthy group.
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Upload Your LabsBartlett M, Ren J, Sarma S, MacNamara J, Brazile T, Wakeham D, et al.. (2026). Skeletal muscle oxidative capacity and tissue composition in heart failure with preserved ejection fraction.. Journal of applied physiology (Bethesda, Md. : 1985). https://doi.org/10.1152/japplphysiol.00683.2026