Table 2.

HR and BB variability measures

	Supine		70° Head-Up Tilt
	POTS subjects	Control subjects	POTS subjects	Control subjects
HR variability	994±153†	3450±520	707±216†	2126±663
LF component	304±45†	842±182	418±151	588±310
HF component	433±84†	1555±395	138±42*	416±223
LF/HF	0.9±0.2	0.5±0.1	4±0.8*	4±1*
BP variability	11±2	15±4	28±4*	26±7
LF component	3±0.5	3±0.8	18±4*	15±6*
HF component	2±0.2	2±1.2	5±0.6*	4±0.7
α, ms/mmHg	12±1†	17±3	5±0.8*†	9±1*
LF
Coherence	0.65±0.03	0.64±0.06	0.78±0.07*	0.85±0.03*
Gain, ms/mmHg	15±1	21±3	4±1*†	8±1*
Phase, °	45±5	32±12	56±6	41±5
HF
Coherence	0.83±0.03	0.79±0.03	0.64±0.06*	0.77±0.04
Gain, ms/mmHg	15±2	27±5	5±1*	9±2*
Phase, °	13±7	2±9	64±7*†	37±11

Values are means ± SE. LF, low frequency; HF, high frequency.

^*P < 0.05 compared with supine values within the same group;

^†P < 0.05 compared with the control group.