There is no consensus at present over the optimal parameter for measuring intensity. Nor is there an agreed optimal intensity for aerobic exercise training in heart failure. At least three approaches have been used: % peak V02, % peak heart rate, and the rating of perceived exertion (RPE).
Intensities of 40% to 80% of peak V02 have successfully used, indicating that patients with low initial exercise tolerance respond to a low exercise intensity. Since intensity and duration are closely interrelated in terms of their expected training effect, a low intensity can partly be compensated by longer or more frequent training sessions.
The rationale for using heart rate as a guide to exercise intensity is based on the relatively linear relationship between heart rate and V02 in exercise training programs. Intensities of 60% to 80% heart rate reserve and 60% to 80% of the predetermined peak heart rate have been used. In heart failure, these recommendations do not take into account the impaired force-frequency relationship in myocardial performance. Since a sustained reduction in heart rate (associated with a change in diastolic function and myocardial metabolism) is of major importance for myocardial recovery, the training heart rate should be as low as possible. This is another reason why the interval training method is preferable because it provides high peripheral exercise stimuli without significantly increasing the heart rate.
Ratings of perceived exertion
In healthy subjects, training intensities of 40% to 80% peak V02 correlate positively with Borg scale RPE values (range: 6 to 20) of between 12 and 15 (light-mod-erate/heavy). In heart failure patients, exercise intensities of RPE <13 (
Rate of exercise progression
In traditional programs, the first improvements in aerobic capacity and symptoms occurred at 4 weeks, and the times to peak response in physical and cardiopulmonary variables were 16 and 26 weeks, respectively, followed by a plateau. During the first weeks, clinically stable patients with very low exercise capacity adapted more rapidly to exercise training than those with higher baseline exercise tolerance. Although the relationship was not linear, it was clear that the rate of training progression had to be tailored individually with respect to baseline functional capacity, clinical status, adaptability, concomitant disease, and age.
Progression has been differentiated into initial, improvement, and maintenance stages:
‚ Initial stage. Intensity should be kept low (40% to 50% peak V02) until achieving an exercise duration of 10 to 15 min. Duration and frequency are increased according to symptoms and clinical status.
‚ Improvement stage. The primary aim is an incremental increase in intensity (50% peak V02 -*60% -*70% and even >80%, if tolerated). A secondary aim is to extend sessions to 15 to 20 min, and if tolerated to 30 min. Intensity is adjusted as soon as a patient performs a given exercise intensity at a decreased RPE and/or exercise tolerance improves vs baseline. In general, the order of progression is duration, then frequency, then intensity.
‚ Maintenance stage. This usually begins after the first
6 months. Further improvements may be minimal. Continuing with an individually tailored training program enables clinically stable patients to maintain their exercise capacity, and/or delay the muscle wasting and loss of aerobic capacity typical in progressive heart failure. It takes only 3 weeks of inactivity to lose the effects of a 3-week residential training program. Exercise training thus needs to be incorporated into the management of heart failure on a continuous long-term basis.
Calisthenics is one of the most common components of exercise training programs in heart failure. The aim is to improve musculoskeletal flexibility, movement coordination, muscle strength, and respiratory capacity, as well as the ability to cope with activities of daily living. Specific recommendations are lacking. Methods should be borrowed from calisthenic programs for cardiac patients with good exercise tolerance and modified for those with heart failure. Exercise position and type should be chosen to avoid a significant increase in preload and afterload, meaning that exercises in the sitting position with arms at body level are preferable. A moderate-to-slow speed, combined with normal rhythmic breathing, is also recommended. The number of separate exercises per session and repetitions per set depends on the patient’s disease status, functional capacity, and response to exercise.