Table 1 Change in 48-h average of heart rate and heart rate variability during 12-month spaceflight ‡.

From: Unconscious mind activates central cardiovascular network and promotes adaptation to microgravity possibly anti-aging during 1-year-long spaceflight

Variable (units)

ISO

Before (157–158 days before launch) (n = 44)

ISS01 (20–21 days after launch) (n = 46)

ISS02 (326–327 days after launch) (n = 44)

After (103–104 days after return to Earth) (n = 39)

Mean ± SD

Mean ± SD

ISS01/Before (%)

Mean ± SD

ISS02/Before (%)

ISS02/ISS01 (%)

Mean ± SD

After/Before (%)

48-h average

Heart Rate

(beats/min)

 

70.8 ±  7.7

70.8 ± 6.6

 

70.9 ± 7.2

  

75.7 ± 6.3**

(106.9)

NN-intervals

msec

 

858.8 ± 88.6

855.4 ± 72.8

 

856.0 ± 69.9

  

799.9 ± 66.6**

(93.1)

r-MSSD

msec

 

16.1 ± 2.5

14.9 ± 1.6**

(92.5)

16.7 ± 2.2##

 

(112.1)

13.2 ± 2.4*

(82.0)

pNN50

%

 

0.59 ± 0.50

0.40 ± 0.32*

(67.8)

1.35 ± 0.71**##

(228.8)

(337.5)

0.50 ± 0.60

 

TF

msec2

 

3579.8 ± 1263.4

3264.4 ± 1887.8

 

4378.1 ± 3841.0

  

3116.5 ± 1263.9

 

ULF

msec2

 

1857.0 ± 1015.9

1373.5 ± 1614.3

 

2427.0 ± 3743.9

  

1602.2 ± 1005.5

 

VLF

msec2

ISO

1322.2 ± 525.4

1350.8 ± 739.9

 

1320.6 ± 677.6

  

1085.5 ± 455.6*

(82.1)

LF

msec2

 

438.7 ± 171.9

464.7 ± 129.6

 

542.2 ± 163.8**##

(123.6)

(116.7)

379.7 ± 186.7

 

LF/HF

–

 

12.9 ± 4.0

13.4 ± 4.0

 

13.0 ± 4.2

  

13.5 ± 3.9

 

HF

msec2

 

35.8 ± 11.3

36.1 ± 7.7

 

44.0 ± 11.1**##

(122.9)

(121.9)

30.4 ± 12.2*

(84.9)

|β|

msec2/Hz

 

0.942 ± 0.328

0.638 ± 0.257**

(67.8)

0.789 ± 0.305*#

(83.7)

(123.5)

0.931 ± 0.343

 

Daytime average

Heart Rate

(beats/min)

 

73.2 ± 7.4

73.4 ± 5.9

 

73.3 ± 7.0

  

78.2 ± 5.3**

(106.8)

NN-intervals

msec

 

828.8 ± 77.8

823.1 ± 56.1

 

827.7 ± 58.3

  

772.1 ± 51.0**

(93.2)

r-MSSD

msec

 

16.5 ± 2.3

14.7 ± 1.6**

(89.3)

17.3 ± 2.1##

 

(117.6)

12.7 ± 2.3**

(77.1)

pNN50

%

 

0.54 ± 0.45

0.29 ± 0.18**

(53.2)

1.45 ± 0.75**##

(268.2)

(504.0)

0.41 ± 0.64

 

TF

msec2

 

3903.9 ± 1346.6

3235.5 ± 2190.5

 

4804.7 ± 4469.5

  

3282.2 ± 1366.5

 

ULF

msec2

 

2274.6 ± 980.5

1606.0 ± 1889.0

 

2954.7 ± 4331.5

  

1941.5 ± 962.2

 

VLF

msec2

ISO

1235.3 ± 514.7

1123.1 ± 652.8

 

1209.6 ± 726.7

  

937.8 ± 386.4*

(75.9)

LF

msec2

 

454.5 ± 177.1

448.5 ± 96.5

 

538.6 ± 164.5##

 

(120.1)

368.7 ± 207.1

 

LF/HF

–

 

13.0 ± 3.7

13.2 ± 3.1

 

11.5 ± 2.7#

 

(87.1)

13.6 ± 3.6

 

HF

msec2

 

36.4 ± 9.7

35.7 ± 7.9

 

47.9 ± 9.8**##

(131.8)

(134.4)

27.7 ± 11.1**

(76.1)

|β|

msec2/Hz

 

1.080 ± 0.298

0.738 ± 0.228**

(68.3)

0.878 ± 0.300*#

(81.4)

(119.0)

1.080 ± 0.232

 

Night-time average

Heart Rate

(beats/min)

 

66.4 ± 6.4

64.1 ± 2.6

 

64.6 ± 2.2

  

69.1 ± 3.6

 

NN-intervals

Msec

 

911.3 ± 83.6

937.3 ± 36.5

 

931.3 ± 31.9

  

870.7 ± 46.1

 

r-MSSD

msec

 

15.6 ± 2.9

15.4 ± 1.5

 

15.3 ± 1.8

  

14.4 ± 2.3

 

pNN50

%

 

0.66 ± 0.58

0.69 ± 0.40

 

1.08 ± 0.52#

 

(155.7)

0.73 ± 0.44

 

TF

msec2

 

3032.7 ± 904.4

3328.7 ± 987.0

 

3311.5 ± 766.3

  

2740.0 ± 940.8

 

ULF

msec2

 

1152.4 ± 616.3

854.7 ± 394.4

 

1107.8 ± 349.2

  

831.2 ± 612.4

 

VLF

msec2

ISO

1474.3 ± 525.0

1928.8 ± 642.1*

(130.8)

1616.5 ± 418.6

  

1461.5 ± 411.1

 

LF

msec2

 

411.1 ± 164.1

505.9 ± 188.7

 

551.8 ± 168.6*

(134.2)

 

407.8 ± 124.1

 

LF/HF

–

 

12.6 ± 4.7

14.0 ± 5.8

 

17.0 ± 5.0*

(135.6)

 

13.3 ± 4.8

 

HF

msec2

 

34.8 ± 14.0

37.4 ± 7.5

 

33.5 ± 6.9

  

37.3 ± 12.6

 

|β|

msec2/Hz

 

0.702 ± 0.225

0.416 ± 0.164**

(59.4)

0.564 ± 0.181#

 

(135.4)

0.549 ± 0.282

 
  1. ISO: Infraslow Oscillation (0.01–0.10 Hz).
  2. TF: (0.0001–0.5) Hz; ULF: (0.0001–0.003) Hz; VLF: (0.003–0.04) Hz; LF: (0.04–0.15) Hz; HF: (0.15–0.40) Hz; β: (0.00013–0.02) Hz.
  3. |β|: slope of fractal scaling, corresponding to periods of 120 to 0.83 min, reflecting the intrinsic autonomic regulatory system.
  4. ‡Tests applied to hourly averages of 5-min intervals in order to eliminate or at least reduce serial correlation.
  5. *P < 0.05; **P < 0.01: ISS01, ISS02 or After vs.Before ; #P < 0.05; ##P < 0.01: ISS02 vs. ISS01.
  6. P-values from Student t-test; SD = standard deviation.
  7. n: number of hourly averages (of 5-min intervals).
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