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Table 1 Frequency domain power (ms 2 ) – (FFT spectrum) ECG data and HRV (heart rate variability) in study participants at night (02.00-04.00 am; n = 9)

From: Increased heart rate variability but no effect on blood pressure from 8 weeks of hatha yoga – a pilot study

 

Before/Baseline

After 8 weeks’ yoga

P-value

Effect size

Confidence interval before

Confidence interval after 8 weeks

LF [ms2]

1237.9 ± 1072.6 Md 852

1335.2 ± 989.1 Md 1346

0.82

0.10

412-2064

574-2097

HF [ms2]

560.7 ± 509.0 Md 454

689.2 ± 505.2 Md 666

0.50

0.27

169-953

300-1078

LF/HF ratio

2.5 ± 1.0 Md 2.2

2.4 ± 1.2 Md 2.3

0.36

0.10

1.7-3.3

1.5-3.3

LF n.u.

69.8 ± 7.9 Md 68.5

66.5 ± 13.1 Md 69.5

0.29

0.32

63.7-75.9

56.4-76.6

HF n.u.

30.2 ± 7.9 Md 31.5

33.5 ± 13.1 Md 30.5

0.29

0.32

24.1-36.3

23.4-43.6

  1. Data are expressed as means ± SD and, when stated, median.
  2. LF = Power in low frequency range (0.04-0.15 Hz). Some researchers believe this involves both sympathetic and parasympathetic modulation (sympathetic involves the blood vessels whereas parasympathetic involves the heart). LF measures withdrawal of vagal tone (Goldstein).
  3. HF = Power in high frequency range (0.15-0.4 Hz), indicates efferent vagal activity.
  4. LF/HF ratio = Ratio is correlated with sympatho-vagal balance.
  5. LF n.u = Represents the relative value of LF power component in proportion to the total power minus the VLF (very low frequency) component in normalized units (n.u).
  6. HF n.u. = Represents the relative value of HF power component in proportion to the total power minus the VLF (very low frequency) component.
  7. n.u. = normalized units.
  8. Confidence interval = 95%.
  9. Md = Median.
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BMC Research Notes

ISSN: 1756-0500

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