Interval training at various intensities (50%, 70%, and 80% of maximal capacity) has shown to be beneficial, but training intensity does not seem to directly influence the magnitude of the increase in exercise tolerance.334 The exercise training regimen varied from general exer- cise to isolated muscle training involving major muscle groups; the setting has varied from supervision to home training; the modality has also been variable, more com- monly treadmill or bicycle ergometry; and the length of training program has been as short as several weeks to as long as a year.335 Therefore, agreement on a universal exercise prescription for HF population does not exist, and an individualized approach with guidance of the AHA exercise standards for testing and training statement is Gas exchange measurements can offer an objective assessment of functional capacity and can be used when feasible to derive the exercise prescription and to monitor changes in functional sta- The most frequently used exercise intensity range is 70% to 80% of peak V , usually determined from a symptom-limited exercise test.335 Common ex- ercise regimens include jogging, calisthenics, walking, use of a treadmill, rowing, use of an arm ergometer, step aerobics, or cycling at 60% to 80% of V max or maximum work capacity for 30 to 40 minutes 3 to 4 Very debilitated patients or those who are not accustomed to aerobic activity may need to initiate the program at a lower intensity (60% or 65% of peak V ) and perform interval training with periods of rest.335 The most commonly used exercise duration is 20 to 30 minutes at the desired intensity.335 Progression should be built into the prescription to adjust the exercise inten- sity as the patient becomes better conditioned. Duration of exercise should include an adequate warm-up period, with this period being longer in the most debilitated patients. 