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Skeletal muscle function and its relation to exercise tolerance in chronic heart failure
D Harrington1, S D Anker, T P Chua
1Department of Cardiac Medicine, National Heart and Lung Institute, Imperial College of Science, Technology and Medicine, London, England, United Kingdom.
Journal of the American College of Cardiology
|December 31, 1997
Summary
Chronic heart failure (HF) patients exhibit reduced muscle strength and bulk, impacting exercise capacity. Muscle atrophy is a key factor limiting physical function in HF.
Area of Science:
- Cardiology
- Exercise Physiology
- Skeletal Muscle Biology
Background:
- Skeletal muscle abnormalities are implicated in reduced exercise capacity in chronic heart failure (HF).
- Previous studies on muscle function in HF have been limited by small sample sizes and inconsistent results, often neglecting muscle wasting.
- Understanding the interplay between muscle mass, function, and exercise tolerance is crucial for managing HF patients.
Purpose of the Study:
- To define the relationship between muscle function and muscle bulk in patients with chronic heart failure (HF).
- To investigate the association between muscle function, muscle bulk, and exercise capacity in chronic HF.
Main Methods:
- One hundred male patients with chronic HF and 31 healthy male controls were assessed.
- Measurements included maximal treadmill oxygen consumption (VO2), quadriceps maximal isometric strength, and computed tomographic (CT) cross-sectional area (CSA) of the thigh.
- Muscle fatigue was evaluated using a 20-minute protocol assessing the percentage of baseline maximal strength maintained.
Main Results:
- Patients with chronic HF demonstrated significantly lower peak VO2, quadriceps CSA, and leg muscle CSA compared to controls.
- Reduced quadriceps maximal isometric strength was observed in HF patients, persisting even after adjusting for muscle CSA, indicating qualitative muscle abnormalities.
- Muscle cross-sectional area (CSA) in patients with HF was a significant predictor of peak absolute VO2.
Conclusions:
- Chronic heart failure (HF) is associated with reduced quadriceps maximal isometric strength due to both quantitative (bulk) and qualitative (intrinsic muscle function) abnormalities.
- Progressive exercise limitation in HF correlates with increasing muscle weakness, primarily driven by loss of quadriceps muscle bulk.
- Muscular atrophy emerges as a major determinant of exercise capacity in patients with chronic heart failure.