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LF/HF Ratio (Autonomic Tone) Calculator
LF/HF Ratio (Autonomic Tone): Explanation and Clinical Context The LF/HF ratio is a key heart rate variability (HRV) parameter reflecting autonomic nervous system balance. LF (low frequency) power represents both sympathetic and parasympathetic activity, while HF (high frequency) power is primarily a marker of parasympathetic (vagal) activity. The LF/HF ratio quantifies the relative contribution of sympathetic vs par