Long-Term Monitoring of Physical Behavior Reveals Different Cardiac Responses to Physical Activity among Subjects with and without Chronic Neck Pain

Table 2

Mean and standard deviation (SD between subjects) of heart rate variability during different physical activity types (sitting/lying, standing, and walking), averaged across work and leisure periods for the pain () and control groups ().

HRV index	Group	Sitting/lying	Standing	Walking
		Mean (SD)	Mean (SD)	Mean (SD)
IBI (ms)	Pain	814 (104)	727 (93)	646 (63)
	Control	865 (100)	762 (90)	665 (72)
RMSSD (ms)	Pain	34 (17)	26 (12)	21 (9)
	Control	40 (19)	30 (12)	23 (8)
LF/HF (ratio)	Pain	3.9 (2.4)	5.3 (2.9)	4.5 (2.0)
	Control	3.1 (1.3)	4.0 (1.8)	4.6 (2.1)

HRV, heart rate variability; IBIs, interbeat intervals; RMSSD, root mean square of successive differences between interbeat intervals; LF/HF, ratio between low- and high-frequency spectral power of heart rate variability.