LETTERS TO THE EDITOR

creased. This would have been the case had this been upright exer-cise,5 6 although this may not have been the case in the unusual posture of these subjects. In relation to the foregoing, the protocol indicates a work load in-crease every 3 minutes with a mean duration of exercise of 8.9 minutes. Their figure 2 suggests that at the first 3-minute point the heart rate was 90 beats/min, the next 110 beats/min, jumping finally (third data point during exercise) to the 152 beats/min peak rate. Was this the actual sequence? The third omission which may or may not be significant is that the protocol makes no mention of the position of the legs at the onset of exercise. Were the legs raised to the level of the pedals dur-ing the control period or only afterward? This factor can affect con-trol stroke volume. These considerations are not intended to detract from, but rather to clarify, a well-done and valuable report