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CLINICAL STUDY: CONGESTIVE HEART FAILURE

Selective low-level leg muscle training alleviates dyspnea in patients with heart failure

^* Division of Circulatory Physiology, Columbia Presbyterian Medical Center, New York, New York, USA

Manuscript received February 12, 2002; revised manuscript received April 24, 2002, accepted June 24, 2002.

^* Reprint requests and correspondence: Dr. Donna M. Mancini, Division of Circulatory Physiology, Department of Medicine, Columbia Presbyterian Medical Center, 622 West 168th Street, New York, New York 10032, USA.
dmm31{at}columbia.edu

OBJECTIVES: The purpose of this study was to demonstrate in patients with moderate to severe heart failure that exertional dyspnea can be alleviated by improving muscle function.

BACKGROUND: Dyspnea is a frequent limiting symptom in patients with chronic heart failure (CHF). This sensation may originate from activation of receptors in the musculature rather than the lung.

METHODS: To investigate whether dyspnea could be alleviated by selective changes in leg muscle function, we performed isolated lower-limb training in 17 patients with severe CHF. Eight patients learned guided imagery relaxation techniques and served as an active control group. Exercise training consisted of three months of low-level bicycle and treadmill exercise such that minute ventilation was <25 l/min. Leg calisthenics were also performed. Maximal and submaximal exercise performance, respiratory and quadriceps muscle strength and endurance and quality-of-life and dyspnea scales were measured before and after each intervention. Metabolic stress testing (VO₂), pulmonary function tests and isokinetic strength testing were also performed.

RESULTS: In the active control group, no changes in leg muscle function, pulmonary function, maximal and submaximal exercise performance or quality-of-life questionnaires were observed. In the training group, peak torque of leg flexors (pre: 39 ± 15 ft-lb; post: 50 ± 13 ft-lb; p < 0.002) increased and the fatigue ratio decreased, indicating improved strength and endurance of the leg muscles. Maximal inspiratory and expiratory mouth pressures and maximum voluntary ventilation were unchanged. Peak VO₂ was increased (pre:12 ± 2.2 ml/kg/min; post: 14 ± 2.6 ml/kg/min) as well as the duration of exercise at 70% peak VO₂ increased (pre: 11.5 ± 3.1 min; post: 21.5 ± 5.4 min; p < 0.003). Perceived dyspnea during the submaximal testing was decreased. Minnesota Living with Heart Failure Score, Guyatt Dyspnea Scale, and the Transitional Dyspnea Index were all improved with training (all p < 0.05).

CONCLUSIONS: We concluded that improvement of limb muscle function alleviates dyspnea and improves exercise performance in patients with CHF.

Abbreviations and Acronyms   BP   blood pressure   CHF   chronic heart failure   HF   heart failure   HR   heart rate   MRT   mean response time   VO2   oxygen consumption