Table 1.

Bivariate Correlations among Outcomes at Baseline

Variable	1.	2.	3.	4.	5.	6.	7.	8.	9.	10.	11.	12.	13.
1. HF-HRV	-	−.53**	−.70**	.83**	.86**	.66**	−.72**	.62**	.84**	.67**	.40	.01	−.15
2. BPM		-	.30	−.18	−.29	−.09	.61**	−.10	−.06	−.29	.16	−.39*	.11
3. HR			-	−.66**	−.64**	−.47**	.38*	−.42*	−.58**	−.97**	−.22	.00	−.05
4. RMSSD				-	.93**	.78**	−.50**	.70**	.93**	.70**	.02	−.10	.00
5. SDNN					-	.83**	−.45**	.83**	.86**	.66**	.07	−.05	.00
6. LF-HRV						-	−.10	.71**	.63**	.49**	.04	−.09	.02
7. LF/HF Ratio							-	−.26	−.47**	−.38*	−.04	−.03	.18
8. VLF-HRV								-	.62**	.43**	.12	.08	.13
9. pNN50									-	.60**	−.06	−.14	.00
10. IBI										-	.22	.03	.19
11. ARA											-	−.12	.30
12. Age												-	.11
13. Sex													-

Note: High frequency heart rate variability (HF-HRV; 0.15 Hz to 0.4 Hz). Respiration rate was measured in breaths-per-minute (BPM). Heart rate measured as the number of beats in 60 seconds (HR). Root mean squared of the successive differences between adjacent N-to-N peaks measured in ms (RMSSD). Standard deviation in N-to-N interval measured in ms (SDNN). Low frequency heart rate variability measured in ms² (LF-HRV). Low frequency to high frequency ratio measured in ms² (LF/HF Ratio). Very low frequency heart rate variability measured in ms² (VLF-HRV). The number of interval differences of successive N to N intervals or heartbeat intervals greater than 50ms divided by the total number of NN intervals yielding a percentage (pNN50). Inter-beat-interval measured in ms (IBI). Abdominal Respiration Amplitude measured in volts (ARA).

^**p<.01 two-tailed.

^*p<.05 two-tailed.