Table 3 Longitudinal comparisons in HRV time domain parameters for older adults randomly assigned to 6 months of Tai Chi vs. usual care.

From: Complexity-Based Measures of Heart Rate Dynamics in Older Adults Following Long- and Short-Term Tai Chi Training: Cross-sectional and Randomized Trial Studies

Outcome measures Tai Chi (n = 26) Usual care (n = 26) Between groups
Baseline 6th month p a Baseline 6th month p a pb for baseline pb for 6th month Group pc Group * Time pc
HR (beats/min) 60.21 ± 7.33 62.42 ± 12.75 0.455 62.08 ± 7.83 64.27 ± 12.36 0.449 0.384 0.597 0.975 0.497
AVNN (ms) 1013.64 ± 123.67 991.22 ± 149.22 0.563 983.42 ± 125.08 959.07 ± 136.13 0.505 0.390 0.421 0.703 0.574
SDNN (ms) 49.72 ± 21.03 45.10 ± 20.71 0.433 40.53 ± 17.29 36.53 ± 13.68 0.359 0.094 0.084 0.206 0.464
RMSSD (ms) 39.57 ± 29.48 33.49 ± 24.50 0.426 26.55 ± 12.50 23.52 ± 10.10 0.341 0.044* 0.061 0.038* 0.409
pNN20 (%) 41.46 ± 24.12 39.58 ± 24.38 0.783 32.32 ± 15.36 29.47 ± 16.14 0.516 0.112 0.084 0.206 0.822
pNN50 (%) 15.66 ± 20.44 12.03 ± 16.94 0.492 5.56 ± 7.97 4.34 ± 5.67 0.527 0.023* 0.033* 0.026* 0.543
  1. ap values calculated from unadjusted linear regression model.
  2. bp values calculated from unadjusted linear regression model.
  3. cp values calculated from linear model adjusting for age and gender.
  4. Abbreviations: HR, heart rate; NN, normal-to-normal heartbeat intervals; AVNN, average NN intervals; SDNN, standard deviations of NN intervals; RMSSD, root mean square of the successive differences; pNN20 and pNN50, percentage of adjacent NN intervals that differ by greater than 20 and 50 milliseconds respectively.