Low-level dynamic exercises for earlier cardiac rehabilitation: aerobic and hemodynamic responses.

Three different kinds of low-level exercise (one arm and two leg exercises) and a low-level treadmill test were designed for patients recovering from acute myocardial infarction; noninvasive circulatory and aerobic responses to these activities were evaluated in healthy subjects. Exercise systolic pressure-rate product (X 10(-2)) were, respectively, 92 +/- 16, 98 +/- 10, 106 +/- 22 and 129 +/- 17 for the four activities studied. Exercise metabolic rates were 1.56 +/- 0.16, 1.99 +/- 0.22, 1.68 +/- 0.25 and 2.74 +/- 0.32 METS (multiples of the observed resting oxygen requirements). Additionally, arteriovenous oxygen difference, cardiac output, stroke volume, mean systemic and mean pulmonary pressures were measured in four coronary patients as they performed the leg exercises. It is hoped that this study will provide a basis for applying these different forms of exercise to patients recovering from an acute myocardial infarction, even when they are confined to bed, in order to advance the onset of cardiac rehabilitation. In a similar way, the new low-level treadmill test may be indicated for the same patients to assess the safety of discharging them from the hospital and permitting unsupervised ambulatory activity at home.