Author + information
- Received August 3, 1994
- Revision received December 16, 1994
- Accepted December 21, 1994
- Published online May 1, 1995.
- Mohamad H. Yamani, MD*,
- Puneet Sahgal, MD*,
- Lauren Wells, PT, MS† and
- Barry M. Massie, MD, FACC*,†,*
- ↵*Address for correspondence: Dr. Barry M. Massie. Cardiology Section (111-C), Veterans Affairs Medical Center, 4150 Clement Street, San Francisco, California 94121.
Objectives. This study investigated whether recovery of skeletal muscle function is impaired in patients with heart failure and whether impaired recovery is associated with abnormal submaximal systemic exercise tolerance during repeated testing.
Background. Patients with heart failure experience fatigue during daily activities. Because abnormalities of skeletal muscle play a role in their exercise intolerance, these symptoms may reflect a delay in muscle recovery and a resulting limitation in submaximal exercise tolerance.
Methods. Two protocols were used. In protocol 1, knee extensor strength and endurance, and their recovery after fatiguing exercise, were evaluated in 11 patients (mean [±SEM] age 62 ± 5 years, New York Heart Association functional class 2.3 ± 0.2, ejection fraction 24 ± 5%) and in 10 age-matched sedentary control subjects. Protocol 2 examined the recovery of knee extensor endurance and submaximal exercise tolerance, as quantified on a self-powered treadmill, over 24 h in 18 patients (mean age 65 ± 3 years, functional class 2.4 ± 0.2, ejection fraction 23 ± 3%) and in 10 control subjects.
Results. Peak oxygen consumption was reduced in both heart failure groups (15.4 ± 1.4 and 15.6 ± 1.0 ml/kg per min) compared with that in the respective control groups (23.1 ± 2.9 and 25.6 ± 1.0 ml/kg per min, both p < 0.05), as was muscle endurance but not muscle strength. In protocol 1, knee extensor endurance recovered more slowly in the patients than in control subjects (to 62 ± 4% and 87 ± 7% of the baseline value after 5 min, respectively, p < 0.05). In protocol 2, submaximal exercise tolerance was lower in the patients with heart failure than in control subjects (1,075 ± 116 vs. 1,390 ± 110 m), but knee extensor endurance and walking distance recovered fully by 10 and 30 min, respectively.
Conclusions. Although these findings confirm earlier studies that demonstrated impaired muscle endurance in patients with heart failure, the results provide no evidence that recovery of either muscle function or submaximal exercise tolerance is delayed beyond the initial 5 to 10 min after exercise.
This study was supported in part by Grants PO1-HL25847 (Dr. Massie) and 5T32-GM0756 (Dr. Sahgal) from the National Institutes of Health, Bethesda, Maryland and by the Department of Veterans Affairs Research Service, Washington, D.C. (Dr. Massie).
All editorial decisions for this article, including selection of referees, were made by a Guest Editor. This policy applies to all articles with authors from the University of California, San Francisco.
- Received August 3, 1994.
- Revision received December 16, 1994.
- Accepted December 21, 1994.
- American College of Cardiology