Table 3.

Physiological responses during pressure‐threshold loading to task failure in men and women

Variable	Time to task failure (min)
	Baseline	1	2	3	4	5	Final
Men
f b (breaths min−1)	10 ± 3	15 ± 0.1a	15 ± 0.1a	15 ± 0.4a	15 ± 0.2a	15 ± 0.8a	14 ± 2a
V T (l)	1.3 ± 0.3	1.6 ± 0.7	1.3 ± 0.4	1.5 ± 0.6	1.4 ± 0.6	1.5 ± 0.6	1.7 ± 0.6
V T/T I (l s−1)	0.69 ± 0.23	0.48 ± 0.20	0.42 ± 0.12	0.46 ± 0.20	0.45 ± 0.20	0.45 ± 0.19	0.52 ± 0.21
$\dot{V}$ E (l min−1)	14 ± 4	24 ± 9a	20 ± 6a	23 ± 9a	22 ± 8a	22 ± 9a	24 ± 9a
$P_{\mathrm{ETC}{\mathrm{O}}_2}$(mmHg)	38 ± 5	32 ± 4a	35 ± 3	37 ± 5b	37 ± 4b	38 ± 4b	38 ± 3b
HR (bpm)	59 ± 8	72 ± 8a	71 ± 7a	72 ± 9a	73 ± 15a	74 ± 11a	79 ± 9a , b
MAP (mmHg)	90 ± 5	93 ± 13	97 ± 14	99 ± 14	100 ± 18	101 ± 16a	104 ± 12a , b
P m (cmH2O)	−1.1 ± 0.4	−82 ± 16a	−80 ± 16a	−81 ± 18a	−81 ± 17a	−82 ± 17a	−81 ± 17a
$\overline{P}$ di/P di,max (%)	8 ± 3	58 ± 6a	56 ± 9a	59 ± 10a	60 ± 7a	59 ± 6a	53 ± 9a
T I/T TOT	0.34 ± 0.03	0.72 ± 0.02a	0.72 ± 0.01a	0.69 ± 0.02a	0.70 ± 0.01a	0.70 ± 0.02a	0.70 ± 0.03a
TTIdi	0.03 ± 0.01	0.42 ± 0.05a	0.40 ± 0.06a	0.41 ± 0.07a	0.42 ± 0.05a	0.41 ± 0.05a	0.37 ± 0.07a , b
Women
f b (breaths min−1)	14 ± 2c	15 ± 0.1	15 ± 0.5	15 ± 0.6	15 ± 0.2	15 ± 0.0	15 ± 1.0
V T (l)	0.8 ± 0.3c	1.2 ± 0.4a	1.0 ± 0.3a	1.0 ± 0.3a	1.0 ± 0.3a	1.0 ± 0.2a	0.7 ± 0.2b , c
V T/T I (l s−1)	0.50 ± 0.15	0.41 ± 0.18	0.36 ± 0.12	0.41 ± 0.16	0.38 ± 0.10	0.39 ± 0.09	0.31 ± 0.14b , c
$\dot{V}$ E (l min−1)	12 ± 5	18 ± 6	14 ± 4c	15 ± 5c	14 ± 4c	15 ± 3c	11 ± 3b , c
$P_{\mathrm{ETC}{\mathrm{O}}_2}$ (mmHg)	38 ± 3	32 ± 5a	33 ± 3a	35 ± 4a	36 ± 3	36 ± 2b	41 ± 1b
HR (bpm)	65 ± 13	73 ± 15	75 ± 14	75 ± 15a	75 ± 16a	75 ± 16a	78 ± 14a
MAP (mmHg)	86 ± 5c	87 ± 9	89 ± 6	90 ± 4	91 ± 4a	92 ± 5a	96 ± 7a
P m (cmH2O)	−0.9 ± 0.2	−63 ± 10a , c	−64 ± 9a , c	−65 ± 10a , c	−64 ± 9a , c	−64 ± 10a , c	−66 ± 16a , c
$\overline{P}$ di/P di,max (%)	6 ± 3	54 ± 7a	53 ± 9a	54 ± 7a	55 ± 8a	57 ± 5a	52 ± 10a
T I/T TOT	0.37 ± 0.05	0.71 ± 0.02a	0.68 ± 0.05a	0.68 ± 0.03a	0.69 ± 0.01a	0.68 ± 0.04a	0.67 ± 0.04a
TTIdi	0.02 ± 0.01	0.38 ± 0.05a	0.36 ± 0.05a	0.36 ± 0.04a	0.38 ± 0.05a	0.39 ± 0.04a	0.34 ± 0.06a

Breathing pattern, heart rate, mean arterial pressure and respiratory muscle pressure generation during PTL. Values are presented as mean ± SD. f _b, breathing frequency; HR, heart rate; MAP, mean arterial pressure; P _di, transdiaphragmatic pressure; $P_{\mathrm{ETC}{\mathrm{O}}_2}$, end‐tidal partial pressure of CO₂; P _m, mouth pressure; $\dot{V}$ _E, minute ventilation; V _T, tidal volume; V _T/T _I, mean inspiratory flow rate; T _I/T _TOT, inspiratory duty cycle; TTI_di, tension–time index of the diaphragm.

^aSignificantly different from rest.

^bsignificantly different from first minute.

^csignificantly different from men (P < 0.05).