The following letters are in response to the Point:Counterpoint series "Cardiovascular variability is/is not an index of autonomic control of circulation" that appears in this issue. To the Editor: The Point:Counterpoint article (5) stimulates a third way of thinking. Since our first study (4) we attempted to obtain noninvasive markers of autonomic cardiovascular regulation. In relation to a simple physiological hypothesis, the sympathovagal balance, we stressed two components of heart rate

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... ability spectrum (LF and HF), normalizing their values to evaluate them independently of variance. We also proposed the LF/HF ratio, and, as an index of vasomotor modulation, LF of blood pressure variability. Evaluation of direct recordings of peripheral nerves and central neurons (1) strengthened the conceptual basis of the approach. Obviously the new tool, like all others, cannot apply to "all conditions," and sympathovagal balance is not a linear phenomenon. The sentence "if one simply knows the angle of tilt, there is no need to assess heart rate variability" (5) indicates that irony is not the only key for understanding. Similarly, there is no paradox in the fact that both vagal and sympathetic recordings may furnish a window on the same central rhythmicity (3) . Finally all authors (5) disregarded the study that has proven beyond any doubt the information content embedded in our approach. With a forecasting linear method, using three variables (HR, LF, and HF normalized), it was possible to discriminate and recognize the supine and the upright position, known to engender distinct levels of sympathovagal balance, in ϳ84% of 350 healthy subjects (2). Is this finding of heuristic value or should we have simply watched the body position?