Table 5.

Partial correlation coefficients of HRV parameters between visit 1 and visit 2.^*

	HRV	N	r	p-value
Resting	RMSSD	391	0.62	< 0.001
	HF	391	0.58	< 0.001
Response	RMSSD	371	0.24	< 0.001
	HF	375	0.16	< 0.001

^*All the partial correlation coefficients were adjusted for sex, ethnicity and age at visit 1.

Responses of RMSSD and HF to stress were indexed by the (stress-rest)/rest ratio.

HF= high frequency power; HRV= heart rate variability; RMSSD= root mean square of successive differences of normal RR intervals.