AUTONOMIC NERVOUS SYSTEM ADAPTATION TO PROGRESSIVE HEAT ACCLIMATION

Andreas D. Flouris,1 Martin Poirier,2 Andrea Bravi,3 Heather E. Wright,2 Geoffrey Green,3 Andrew J. Seely,3 Glen P. Kenny2

1FAME Laboratory, Centre for Research and Technology Hellas, Trikala, Greece, 42100.

2Human and Environmental Physiology Research Unit, Faculty of Health Sciences, School of Human Kinetics, University of Ottawa, Ottawa, Canada, K1N 6N5.

3Divisions of Thoracic Surgery and Critical Care Medicine, Ottawa Hospital-General Campus, Ottawa Health Research Institute, Ontario, Canada, K1H 8L6.

MATERIALS AND METHODS

Heart Rate Variability

R-R interval data were extracted from 175Hz ECG waveforms throughout all heat tolerance tests using a 5-lead Holter DigiTrak XT (Philips, Andover, USA) and those deemed to be normal-to-normal (NN) were retained for further analysis. Using the NN interval time series of each subject (total of three NN interval series), HRV analyses were performed employing the Continuous Individualized Variability Analysis – CIMVATM software (http://ohridal.org/cimva/CIMVA-Core-Description.pdf) to extract a total of 102 measures of variability computed from the statistical, geometric, informational, energetic, and invariant domains. The list of all 102 variability measures computed is provided in Supplementary Table 1. We used a 5-min window analysis with 30 seconds time step to effectively assess the transients between the different phases of the protocol.

LIST OF TABLES

Supplementary Table 1. The list of all 102 variability measures computed.
# / Variability measure / Variability domain
1 / Mean / Statistical
2 / Mean rate / Statistical
3 / Standard deviation / Statistical
4 / Coefficient of variation / Statistical
5 / Poincaré plot SD1 / Geometric
6 / Poincaré plot SD2 / Geometric
7 / Root mean square of successive differences / Statistical
8 / Sample entropy / Informational
9 / LF/HF ratio computed with Lomb-Scargle periodogram / Energetic
10 / LF power computed with Lomb-Scargle periodogram / Energetic
11 / HF power computed with Lomb-Scargle periodogram / Energetic
12 / Wavelet area under the curve / Energetic
13 / Detrended fluctuation analysis: a1 / Invariant
14 / Detrended fluctuation analysis: a2 / Invariant
15 / Largest Lyapunov exponent / Invariant
16 / Correlation dimension global exponent / Invariant
17 / Skewness / Statistical
18 / Kurtosis / Statistical
19 / Power Law Slope computed with Welch's method / Invariant
20 / Power Law Y-Intercept computed with Welch's method / Invariant
21 / Power Law X-Intercept computed with Welch's method / Invariant
22 / Power Law Goodness of Fit computed with Welch's method / Invariant
23 / Power Law Slope computed with Lomb-Scargle periodogram / Invariant
24 / Power Law Y-Intercept computed with Lomb-Scargle periodogram / Invariant
25 / Power Law X-Intercept computed with Lomb-Scargle periodogram / Invariant
26 / Power Law Goodness of Fit computed with Lomb-Scargle periodogram / Invariant
27 / Power Law Slope computed with histogram / Invariant
28 / Power Law Y-Intercept computed with histogram / Invariant
29 / Power Law X-Intercept computed with histogram / Invariant
30 / Power Law Goodness of Fit computed with histogram / Invariant
31 / Detrended fluctuation analysis area under the curve / Invariant
32 / Multiscale Entropy / Informational
33 / LF/HF ratio computed with Welch's method / Energetic
34 / VLF power computed with Welch's method / Energetic
35 / LF power computed with Welch's method / Energetic
36 / HF power computed with Welch's method / Energetic
37 / VLF power computed with Lomb-Scargle periodogram / Energetic
38 / Hjorth parameter: activity / Energetic
39 / Hjorth parameter: mobility / Energetic
Supplementary Table 1 cont. The list of all 102 variability measures computed.
# / Variability measure / Variability domain
40. / Hjorth parameter: complexity / Energetic
41. / Embedding scaling exponent / Invariant
42. / Recurrence quantification analysis: percentage of recurrences / Geometric
43. / Recurrence quantification analysis: percentage of determinism / Geometric
44. / Recurrence quantification analysis: maximum diagonal line / Geometric
45. / Recurrence quantification analysis: average diagonal line / Geometric
46. / Recurrence quantification analysis: Shannon entropy of the diagonals / Geometric
47. / Recurrence quantification analysis: determinism/recurrences / Geometric
48. / Recurrence quantification analysis: percentage of laminarity / Geometric
49. / Recurrence quantification analysis: maximum vertical line / Geometric
50. / Recurrence quantification analysis: trapping time / Geometric
51. / Recurrence quantification analysis: Shannon entropy of the vertical lines / Geometric
52. / Shannon entropy / Geometric
53. / Plotkin and Swamy energy operator average energy / Energetic
54. / Teager energy operator average energy / Energetic
55. / Symbolic dynamics: percentage of 0 variations sequences, uniform case / Statistical
56. / Symbolic dynamics: percentage of 1 variations sequences, uniform case / Statistical
57. / Symbolic dynamics: percentage of 2 variations sequences, uniform case / Statistical
58. / Symbolic dynamics: percentage of 0 variations sequences, non-uniform case / Statistical
59. / Symbolic dynamics: percentage of 1 variations sequences, non-uniform case / Statistical
60. / Symbolic dynamics: percentage of 2 variations sequences, non-uniform case / Statistical
61. / Symbolic dynamics: forbidden words, uniform case / Statistical
62. / Symbolic dynamics: forbidden words, non-uniform case / Statistical
63. / Symbolic dynamics: Shannon entropy, uniform case / Informational
64. / Symbolic dynamics: Shannon entropy, non-uniform case / Informational
65. / Symbolic dynamics: modified conditional entropy, uniform case / Informational
66. / Symbolic dynamics: modified conditional entropy, non-uniform case / Informational
67. / Form factor / Statistical
68. / Fuzzy entropy / Informational
69. / Grid transformation feature: grid count / Geometric
70. / Grid transformation feature: AND similarity index / Informational
71. / Grid transformation feature: time delay similarity index / Informational
72. / Grid transformation feature: weighted similarity index / Informational
Supplementary Table 1 cont. The list of all 102 variability measures computed.
# / Variability measure / Variability domain
73. / Correlation dimension local exponent / Invariant
74. / Rescaled detrended range analysis / Invariant
75. / Higuchi scaling exponent / Invariant
76. / Allan factor distance from a Poisson distribution / Informational
77. / Fano factor distance from a Poisson distribution / Informational
78. / Index of variability distance from a Poisson distribution / Informational
79. / Finite growth rate / Invariant
80. / Scaled windowed variance / Invariant
81. / Kullback-Leibler permutation entropy / Informational
82. / Multiscale time irreversibility asymmetry index / Energetic
83. / Lee parameter / Statistical
84. / Poincaré plot cardiac sympathetic index / Geometric
85. / Poincaré plot cardiac vagal index / Geometric
86. / Mean of the differences / Statistical
87. / Standard deviation of the differences / Statistical
88. / Interquartile range / Statistical
89. / Predictive feature: error from an Autoregressive model / Informational
90. / Similarity index of the distributions / Informational
91. / Multifractal spectrum cumulant of the first order / Invariant
92. / Multifractal spectrum cumulant of the second order / Invariant
93. / Multifractal spectrum cumulant of the third order / Invariant
94. / Kolmogorov-Sinai entropy / Invariant
95. / Scale dependent Lyapunov exponent slope / Invariant
96. / Scale dependent Lyapunov exponent mean value / Invariant
97. / Dynamical moment of the second order / Geometric
98. / Dynamical moment of the third order along the principal bisector / Geometric
99. / Dynamical moment of the third order along the secondary bisector / Geometric
100. / Dynamical moment of the third order along the x axes / Geometric
101. / Dynamical moment of the third order along the y axes / Geometric
102. / Diffusion entropy / Informational

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