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Table 1 Respiratory variables during rest in room air, He-O2, Ar-O2, and SF6-O2 breathing.

From: Loading and unloading breathing during exercise: respiratory responses and compensatory mechanisms

Parameters

Room Air

He-O 2

Room air

Ar-O 2

Room air

SF 6 -O 2

VE, l/min

8.89 ± 0.51

9.28 ± 0.56

9.06 ± 0.50

9.07 ± 0.54

9.01 ± 0.69

8.95 ± 0.55

VT, l

0.86 ± 0.18

0.92 ± 0.19

0.79 ± 0.11

0.85 ± 0.14

0.86 ± 0.17

0.94 ± 0.15*

TI, s

2.46 ± 0.62

2.42 ± 0.56

2.11 ± 0.38

2.36 ± 0.48

2.51 ± 0.58

2.94 ± 0.70

TE, s

3.43 ± 0.58

3.52 ± 0.69

3.38 ± 0.44

3.44 ± 0.51

3.53 ± 0.55

3.59 ± 0.51

TT, s

5.59 ± 0.78

5.95 ± 1.15

5.49 ± 0.78

5.80 ± 0.99

6.04 ± 1.14

6.53 ± 1.15*

f, cycle/min

12.7 ± 1.4

12.5 ± 1.4

13.2 ± 1.7

12.7 ± 1.5

12.3 ± 1.5

11.3 ± 1.7*

PACO2, mmHg

33.9 ± 1.1

33.5 ± 1.2

33.9 ± 1.1

34.9 ± 1.2

33.3 ± 0.7

33.4 ± 1.0

VImax, l/s

0.42 ± 0.02

0.57 ± 0.04*

0.48 ± 0.04

0.50 ± 0.03

0.44 ± 0.02

0.34 ± 0.02*

PIm, cmH2O

0.70 ± 0.05

0.46 ± 0.07*

0.76 ± 0.06

0.80 ± 0.12

0.74 ± 0.05

1.05 ± 0.03**

WI, kgm/min

0.06 ± 0.01

0.04 ± 0.07

0.07 ± 0.01

0.07 ± 0.01

0.07 ± 0.01

0.01 ± 0.01**

dP/dtI, mmH2O/s

32.40 ± 3.17

23.35 ± 2.71*

31.30 ± 3.69

37.50 ± 4.64

32.70 ± 3.38

57.80 ± 8.19**

  1. Data are means ± SE. VE, minute ventilation; VT, tidal volume; TI, inspiratory time; TE, expiratory time; TT, total breath duration; f, breath frequency; PACO2, end-tidal partial pressure; VImax, inspiratory flow rate; PIm, inspiratory mouth pressure; WI, inspiratory work of breathing; dP/dtI, maximum rate of inspiratory mouth pressure change. *P < 0.05, **P < 0.01 - significant differences between air and He-O2 and SF6-O2 breathing. The differences between air and Ar-O2 breathing were insignificant.