1 Introduction
2 Methods
2.1 Experimental design
2.2 Statistical analysis
3 Results
3.1 Participants
3.2 HRV and PRV measures at various ambient temperatures
Variable | Method | Temperature condition (mean ± SD) | ||
---|---|---|---|---|
T
l
|
T
m
|
T
h
| ||
AVNN (ms) | HRV | 799.1 ± 89.0 | 754.6 ± 82.1 | 720.8 ± 87.8 |
PRV | 799.1 ± 89.0 | 754.6 ± 82.2 | 720.8 ± 87.8 | |
P value | 0.093 | 0.103 | 0.249 | |
SDNN (ms) | HRV | 54.7 ± 21.5 | 45.7 ± 18.7 | 39.6 ± 18.4 |
PRV | 55.3 ± 21.3 | 46.4 ± 18.5 | 40.6 ± 18.2 | |
P value | *** | ** | *** | |
SDSD (ms) | HRV | 44.2 ± 21.3 | 31.9 ± 16.5 | 27.1 ± 16.5 |
PRV | 44.6 ± 20.5 | 32.2 ± 15.6 | 28.0 ± 15.8 | |
P value | 0.088 | 0.434 | ** | |
RMSSD (ms) | HRV | 44.1 ± 21.3 | 31.9 ± 16.4 | 27.1 ± 16.5 |
PRV | 44.5 ± 20.5 | 32.2 ± 15.5 | 27.9 ± 15.8 | |
P value | 0.088 | 0.434 | ** | |
NN50 (sample) | HRV | 39.3 ± 34.5 | 21.8 ± 28.6 | 17.0 ± 27.5 |
PRV | 40.2 ± 33.3 | 22.1 ± 28.7 | 18.1 ± 28.3 | |
P value | 0.182 | 0.555 | 0.084 | |
pNN50 (%) | HRV | 11.2 ± 10.3 | 5.9 ± 8.0 | 4.6 ± 7.7 |
PRV | 11.3 ± 9.9 | 6.0 ± 7.9 | 4.8 ± 7.8 | |
P value | 0.318 | 0.608 | 0.105 | |
VLF (ms2) | HRV | 134.6 ± 76.0 | 114.2 ± 66.8 | 98.5 ± 54.3 |
PRV | 135.0 ± 76.1 | 114.6 ± 67.1 | 98.8 ± 54.5 | |
P value | *** | *** | *** | |
LF (ms2) | HRV | 197.2 ± 110.6 | 153.3 ± 66.8 | 142.1 ± 66.9 |
PRV | 200.2 ± 110.8 | 156.6 ± 69.0 | 145.5 ± 68.2 | |
P value | *** | *** | *** | |
HF (ms2) | HRV | 261.4 ± 126.2 | 196.1 ± 111.9 | 174.0 ± 105.1 |
PRV | 268.3 ± 123.2 | 203.8 ± 106.6 | 186.5 ± 103.0 | |
P value | *** | ** | *** | |
LF/HF (n.u.) | HRV | 0.790 ± 0.246 | 0.880 ± 0.308 | 0.979 ± 0.437 |
PRV | 0.774 ± 0.235 | 0.844 ± 0.287 | 0.897 ± 0.367 | |
P value | * | *** | ** | |
nLF (n.u.) | HRV | 0.330 ± 0.071 | 0.345 ± 0.089 | 0.364 ± 0.101 |
PRV | 0.330 ± 0.069 | 0.345 ± 0.087 | 0.357 ± 0.095 | |
P value | 0.928 | 0.852 | ** | |
nHF (n.u.) | HRV | 0.434 ± 0.066 | 0.414 ± 0.079 | 0.404 ± 0.083 |
PRV | 0.443 ± 0.067 | 0.430 ± 0.078 | 0.426 ± 0.081 | |
P value | *** | *** | *** |
3.3 Comparison of HRV and PRV analysis in temperature changes
Variable (unit) | Temperatures | Mean ± SD | Temperature difference | Mean difference |
---|---|---|---|---|
AVNN
R
a
(n.u.) |
T
l
| 1.000 ± 0.000 |
T
l–T
m
| 0.000 |
T
m
| 1.000 ± 0.000 |
T
m–T
h
| 0.000 | |
T
h
| 1.000 ± 0.000 |
T
l–T
h
| 0.000 | |
SDNN
R
b
(n.u.) |
T
l
| 1.015 ± 0.013 |
T
l–T
m
| −0.005 |
T
m
| 1.020 ± 0.025 |
T
m–T
h
| −0.010 | |
T
h
| 1.030 ± 0.022 |
T
l–T
h
| −0.015* | |
SDSD
R
b
(n.u.) |
T
l
| 1.020 ± 0.035 |
T
l–T
m
| −0.004 |
T
m
| 1.023 ± 0.062 |
T
m–T
h
| −0.036 | |
T
h
| 1.059 ± 0.070 |
T
l–T
h
| −0.040* | |
RMSSD
R
b
(n.u.) |
T
l
| 1.020 ± 0.035 |
T
l–T
m
| −0.004 |
T
m
| 1.023 ± 0.062 |
T
m–T
h
| −0.036 | |
T
h
| 1.059 ± 0.070 |
T
l–T
h
| −0.040* | |
NN50
R
a
(n.u.) |
T
l
| 1.166 ± 0.416 |
T
l–T
m
| 0.133 |
T
m
| 1.033 ± 0.261 |
T
m–T
h
| −0.100 | |
T
h
| 1.133 ± 0.286 |
T
l–T
h
| 0.033 | |
pNN50
R
a
(n.u.) |
T
l
| 1.166 ± 0.416 |
T
l–T
m
| 0.133 |
T
m
| 1.033 ± 0.261 |
T
m–T
h
| −0.100 | |
T
h
| 1.133 ± 0.286 |
T
l–T
h
| 0.033 | |
VLF
R
a
(n.u.) |
T
l
| 1.003 ± 0.004 |
T
l–T
m
| −0.001 |
T
m
| 1.004 ± 0.004 |
T
m–T
h
| 0.001 | |
T
h
| 1.003 ± 0.004 |
T
l–T
h
| −0.000 | |
LF
R
a
(n.u.) |
T
l
| 1.018 ± 0.015 |
T
l–T
m
| −0.002 |
T
m
| 1.021 ± 0.023 |
T
m–T
h
| −0.005 | |
T
h
| 1.026 ± 0.019 |
T
l–T
h
| −0.008 | |
HF
R
b
(n.u.) |
T
l
| 1.038 ± 0.049 |
T
l–T
m
| −0.021 |
T
m
| 1.059 ± 0.052 |
T
m–T
h
| −0.047* | |
T
h
| 1.106 ± 0.093 |
T
l–T
h
| −0.068** | |
LF/HF
R
b
(n.u.) |
T
l
| 0.982 ± 0.037 |
T
l–T
m
| 0.017 |
T
m
| 0.965 ± 0.036 |
T
m–T
h
| 0.032 | |
T
h
| 0.933 ± 0.062 |
T
l–T
h
| 0.050*** | |
nLF
R
a
(n.u.) |
T
l
| 1.002 ± 0.025 |
T
l–T
m
| −0.001 |
T
m
| 1.003 ± 0.035 |
T
m–T
h
| 0.018 | |
T
h
| 0.986 ± 0.035 |
T
l–T
h
| 0.017 | |
nHF
R
b
(n.u.) |
T
l
| 1.021 ± 0.024 |
T
l–T
m
| −0.019 |
T
m
| 1.040 ± 0.025 |
T
m–T
h
| −0.019 | |
T
h
| 1.060 ± 0.049 |
T
l–T
h
| −0.038*** | |
PTTa (ms) |
T
l
| 399.8 ± 20.1 |
T
l–T
m
| −9.951 |
T
m
| 408.7 ± 15.4 |
T
m–T
h
| 4.761 | |
T
h
| 402.6 ± 17.1 |
T
l–T
h
| 5.189 | |
SDPTTb (ms) |
T
l
| 7.8 ± 2.2 |
T
l–T
m
| 1.851** |
T
m
| 5.9 ± 2.2 |
T
m–T
h
| 0.745 | |
T
h
| 5.2 ± 1.7 |
T
l–T
h
| 2.596*** |