Table 2.
Effects of pregnancy on perceptual, cardio-metabolic, ventilatory and respiratory mechanical/muscular responses at the symptom-limited peak (i.e. last 30 s of loaded pedalling) and at the highest equivalent work rate (HEWR) of cycle exercise
| Peak exercise | HEWR | |||
|---|---|---|---|---|
| PP | TM3 | PP | TM3 | |
| Breathlessness (Borg scale) | 5.4 ± 0.6 | 6.5 ± 0.5* | 3.2 ± 0.4 | 4.1 ± 0.3* |
| Leg discomfort (Borg scale) | 6.6 ± 0.7 | 6.5 ± 0.6 | 4.1 ± 0.5 | 4.5 ± 0.5 |
| Work rate (W) | 155 ± 7 | 148 ± 5 | 128 ± 5 | 128 ± 5 |
| V̇O2 (l min−1) | 2.13 ± 0.08 | 2.12 ± 0.08 | 1.67 ± 0.06 | 1.82 ± 0.07† |
| V̇O2 (% predicted max) | 111 ± 4 | 110 ± 3 | 87 ± 2 | 94 ± 3† |
| V̇CO2 (l min−1) | 2.58 ± 0.08 | 2.40 ± 0.08* | 1.91 ± 0.07 | 1.99 ± 0.08 |
| HR (beats min−1) | 174 ± 3 | 168 ± 3‡ | 158 ± 4 | 157 ± 2 |
| O2 pulse (ml beat−1) | 12.3 ± 0.5 | 12.7 ± 0.5 | 10.7 ± 0.5 | 11.6 ± 0.5* |
| MAP (mmHg) | 104 ± 1 | 107 ± 1 | 102 ± 2 | 105 ± 5 |
| V̇E (l min−1) | 79.1 ± 2.6 | 81.5 ± 4.1 | 52.5 ± 2.6 | 62.7 ± 3.2‡ |
| V̇E/MVC (%) | 72.8 ± 3.2 | 71.5 ± 3.5 | 48.3 ± 2.7 | 54.7 ± 2.4† |
| VT (l) | 2.08 ± 0.08 | 2.22 ± 0.07† | 1.88 ± 0.09 | 2.22 ± 0.12‡ |
| VT/IC (%) | 71.8 ± 2.2 | 72.4 ± 2.3* | 61.8 ± 2.0 | 71.2 ± 2.8‡ |
| IC (l) | 2.92 ± 0.11 | 3.08 ± 0.08 | 3.04 ± 0.12 | 3.11 ± 0.08 |
| IC change from rest (l) | 0.21 ± 0.09 | −0.00 ± 0.10# | 0.33 ± 0.10 | 0.03 ± 0.09† |
| IRV (l) | 0.84 ± 0.08 | 0.86 ± 0.08 | 1.16 ± 0.08 | 0.89 ± 0.09† |
| fR (breaths min−1) | 38.7 ± 1.9 | 37.2 ± 2.0 | 28.4 ± 1.3 | 28.6 ± 1.3 |
| TI/TTOT (%) | 50.4 ± 0.9 | 48.7 ± 0.8 | 46.5 ± 0.7 | 47.3 ± 0.8 |
| VT/TI (l s−1) | 2.57 ± 0.11 | 2.77 ± 0.13 | 1.87 ± 0.07 | 2.20 ± 0.10† |
| VT/TE (l s−1) | 2.61 ± 0.09 | 2.65 ± 0.16 | 1.65 ± 0.10 | 1.98 ± 0.11‡ |
| SpO2 (%) | 94.5 ± 1.0 | 95.1 ± 0.6 | 95.5 ± 0.4 | 95.0 ± 0.6 |
| PETCO2 (mmHg) | 35.3 ± 0.9 | 32.6 ± 1.1* | 39.9 ± 1.1 | 35.1 ± 1.0‡ |
| V̇E/V̇O2 | 37.5 ± 1.4 | 38.6 ± 1.4 | 31.5 ± 1.2 | 34.5 ± 1.1† |
| V̇E/V̇CO2 | 30.8 ± 0.9 | 33.8 ± 1.0† | 27.4 ± 0.8 | 31.5 ± 0.8‡ |
| Peak inspiratory Poes (cmH2O) | −12.1 ± 0.9 | −14.4 ± 0.9 | −11.0 ± 0.9 | −13.3 ± 0.8# |
| Peak expiratory Poes (cmH2O) | 9.3 ± 0.9 | 10.5 ± 1.2 | 5.6 ± 1.0 | 7.0 ± 0.9 |
| Tidal Poes (cmH2O) | 21.4 ± 1.3 | 24.8 ± 1.7* | 16.9 ± 1.2 | 20.3 ± 1.2† |
| Tidal Poes/PImax (%) | 40.6 ± 4.3 | 49.8 ± 4.4# | 31.5 ± 3.9 | 40.2 ± 3.1* |
| Tidal Poes/PImax: VT/VC | 0.81 ± 0.11 | 0.94 ± 0.09 | 0.69 ± 0.09 | 0.76 ± 0.06 |
| Tension time index | 0.08 ± 0.01 | 0.08 ± 0.01 | 0.06 ± 0.01 | 0.07 ± 0.01 |
| WIres (joules min−1) | 45.1 ± 3.3 | 54.1 ± 8.2 | 23.0 ± 3.5 | 30.4 ± 5.4* |
| WEres (joules min−1) | 76.2 ± 6.6 | 79.2 ± 11.2 | 30.4 ± 5.8 | 41.8 ± 6.5‡ |
| WRES (joules min−1) | 121.3 ± 9.2 | 133.3 ± 8.8 | 53.5 ± 9.1 | 72.1 ± 11.5† |
| WIel (joules min−1) | 110.3 ± 6.5 | 132.2 ± 13.5# | 77.5 ± 4.1 | 109.1 ± 11.4† |
| WOB (joules min−1) | 155.5 ± 8.2 | 186.3 ± 18.6# | 110.6 ± 6.3 | 139.5 ± 14.2† |
| RL (cmH2O l−1 s−1) | 2.55 ± 0.15 | 2.65 ± 0.17 | 2.41 ± 0.16 | 2.55 ± 0.29 |
P < 0.05
P < 0.01
P < 0.001
P≤ 0.07 TM3versus PP. Values are means ±s.e.m. PP, postpartum; TM3, third trimester; O2, oxygen; CO2, carbon dioxide; V̇O2, metabolic rate of O2 uptake; V̇CO2, metabolic rate of CO2 production; HR, heart rate; MAP, mean arterial pressure; V̇E, minute ventilation; MVC, maximal ventilatory capacity estimated as FEV1× 35; VT, tidal volume; IC, inspiratory capacity; IRV, inspiratory reserve volume; fR, breathing frequency; TI/TTOT, inspiratory duty cycle; VT/TI and VT/TE, mean tidal inspiratory and expiratory flow, respectively; SpO2, arterial O2 saturation; PETCO2, end-tidal CO2 tension; V̇E/V̇O2 and V̇E/V̇CO2, ventilatory equivalent for O2 and CO2, respectively; Poes, oesophageal pressure; PImax, maximum inspiratory (negative) oesophageal pressure; VC, vital capacity; WIres, inspiratory flow resistive work of breathing; WEres, expiratory flow resistive work of breathing; WRES, total resistive work of breathing; WIel, inspiratory elastic work of breathing; WOB, total inspiratory work of breathing; RL, pulmonary resistance.