. Author manuscript; available in PMC: 2013 Apr 1.

Published in final edited form as: J Occup Environ Med. 2012 Apr;54(4):466–470. doi: 10.1097/JOM.0b013e318246f1d4

Table 5.

Heart rate variability frequency-domain indices with spontaneous breathing.

HRV Frequency-Domain Indices	Measurement Time Point
HRV Frequency-Domain Indices	0-h	4-h
LFn (nu)	58.1 ± 16.7	56.2 ± 15.9
HFn (nu)	41.9 ± 16.7	43.8 ± 15.9
LF (ms²)	799.9 ± 1492.6	625.5 ± 1004.2
HF (ms²)	751.5 ± 1793.7	618.2 ± 1132.7
LF/HF ratio	1.81 ± 1.3	1.7 ± 1.3

Data presented as mean ± SD. Measurement time points refer to the time of the sample collection (0-h: immediately before; 4-h: immediately after). N=25. LF: low frequency component; HF: high frequency component; LFn: normalized low frequency component; HFn: normalized high frequency component; nu: normalized unit.