Resistance exercise training

There has been little enthusiasm for resistance exercise, primarily because of the potentially harmful cardiovascular responses observed to sustained isometric hand grip exercising for >3 min. These included marked increases in systemic vascular resistance and decreases in left ventricular ejection fraction and stroke work index, indicating acute left ventricular overload. In contrast, during a rhythmic single-leg press exercise performed in 2 sets of 10 repetitions each at a load 70% of one maximum repetition, heart rate and rate x pressure product were lower, and systolic blood pressure, ejection fraction, and diastolic and systolic volume were no greater, than those during cycle ergometer exercising at an intensity 70% of peak V02. Additionally, during interval rhythmic double-leg press exercise at loads 60% and 80% of maximum voluntary contraction (60 s work phases of

12 repetitions each with 120 s rest phases), heart failure patients showed an increased left ventricular stroke work index and decreased systemic vascular resistance, suggesting enhanced left ventricular function. This could be due to a rhythmic sequence of submaximal isometric muscle contractions, which help to maintain venous return, reduce systemic vascular resistance, maintain muscle blood flow, and meet muscle metabolic need.

The amount of cardiovascular stress expected during resistance exercise also depends on the muscle group/mass involved (single leg/arm vs double leg/arm). Double-arm exercise with a given load causes greater cardiovascular stress than single-arm exercise. Thus, in patients in advanced heart failure and/or with a very low exercise tolerance, resistance exercise training can be applied in a segmental fashion, meaning the contraction of small muscle groups or a limited muscle mass.

In summary, rhythmic strength exercise appears a promising training method in heart failure if small muscle groups are recruited, using short work phases, few repetitions, and a work/recovery-ratio of 1:2. However, more experience in larger patient populations is needed before a general recommendation can be given.

Respiratory training

Respiratory muscle strength and endurance can be increased by resistive inspiratory muscle training. Patients with heart failure or chronic obstructive pulmonary disease have been managed with an inspiratory muscle trainer ([IMT], eg, Threshold®, Respironics Healthscan Asthma and Allergy Products, Pittsburgh, PA 15221, USA) for a minimum of 20 to 30 min/day for 3 to 5 days/week. The intensity should be 25% to 35% of maximum inspiratory pressure (PI max) measured at functional residual capacity. If this cannot be maintained for 15 min, the intensity can be reduced. End points are the before/after differences in dyspnea, maximum inspiratory and expiratory pressure, and exercise performance. Exercises to strengthen the abdominal muscles are also recommended, eg, exhaling in the supine position with head and shoulders raised and the abdomen maximally retracted. Similar exercises can be carried out in the sitting position.

Yoga has been shown to improve coordination of the respiratory muscles and diaphragm, and to lower the respiratory rate. Inspiration and expiration at a controlled frequency (15,10, or 6 breaths/min) can be used to mobilize the diaphragm, abdominal muscles, and lower and upper chest muscles in sequence. This helps to improve respiratory awareness, decrease the resting respiratory rate, increase tidal volume, and hence decrease atelectasis.

Further reading

Working Group on Cardiac Rehabilitation & Exercise Physiology Recommendations for exercise training in chronic heart failure patients. Eur Heart and Working Group on Heart Failure of the European Society of Cardiology. J. 2001 ;22:125-135.

Keywords

management; physical activity; aerobic exercise; resistance exercise; V02; heart rate; respiratory training; rehabilitation

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