Figures
- FIGURE 1
Enrolment and inclusion of study participants.
- FIGURE 2
Perceptual ratings during constant work rate exercise tests pre- and post-training for a) and c) dyspnoea and b) and d) leg fatigue. Values represent mean±sd. Open symbols: pre-training; black symbols: post-training; triangles: iso-time. *: p>0.05.
- FIGURE 3
Ventilatory responses during constant work rate exercise tests pre- and post-training. Values represent mean±sd. Open symbols: pre-training; black symbols: post-training; triangles: iso-time; fB: breathing frequency; VʹE: minute ventilation; VT: tidal volume. *: p<0.05.
- FIGURE 4
Respiratory pressures during constant work rate exercise tests pre- and post-training. Values represent mean±sd. Open symbols: pre-training; black symbols: post-training; triangles: iso-time; Pdi,av: average transdiaphragmatic pressure during inspiration; Pes,av: average oesophageal pressure during inspiration; Pga,av: average gastric pressure during inspiration; Pga,rise: average increase in gastric pressure during expiration. *: p<0.05.
- FIGURE 5
Respiratory muscle activity during constant work rate exercise tests pre- and post-training. Values represent mean±sd. Open symbols: pre-training; black symbols: post-training; triangles: iso-time; EMGdi: electromyography of the diaphragm; EMGsca: electromyography of the scalene; EMGscm: electromyography of the sternocleidomastoid.
Tables
- TABLE 1
Baseline participant characteristics
IMT (n=10) Control (n=5) Demographics Male, n (%) 7 (70) 4 (80) Age, years 63±6.6 56.6±10.8 Weight, kg 89±21.2 93.2±16.4 Height, cm 175±10.3 177±12.6 BMI, kg·m−2 28.8±3.6 29.5±1.4 BDI score, 0–12 scale 6.5±1.8 7.6±1.7 Left-side paralysis, n (%) 4 (40) 4 (80) Pulmonary function FVC, % predicted 72±7 65±9 FEV1, % predicted 66±5 58±8 FEV1/FVC, ratio 0.71±0.08 0.74±0.09 FVCsupine-FVCseated, % dif −29±9 −24±8 IC, % predicted 81±14 66±32 TLC, % predicted 79±38 75±35 RV, % predicted 107±54 105±49 FRC, % predicted 83±41 76±34 TLCO, % predicted 84±44 55±25 KCO, % predicted 117±61 97±43 Respiratory muscle strength PI,max, % predicted 80±20 83±16 PE,max, cmH2O, % predicted 169±72 143±65 Peak incremental exercise Work rate, Watts 134±40 163±64 Work rate, % predicted 95±19 101±19 Heart rate, beats·min−1 130±47 127±62 Heart rate, % predicted 84±30 77±36 VʹO2, L·min−1 2.0±0.6 2.5±1.4 VʹO2, % predicted 89±13 107±49 VʹO2, L·min−1 2.1±0.6 2.8±1.5 VʹE, L·min−1 63.4±17.9 74.2±38.5 VʹE/MVV, % 74±32 98±49 VʹE/VʹCO2 30.9±3.6 27.1±12.3 RER 1.07±0.10 1.09±0.49 O2 pulse, ml·beat−1 15.4±7.3 19.8±9.3 SpO2, % 95±40 91±41 Dyspnoea, 0–10 scale 8.0±1.7 9.8±0.4 Leg effort, 0–10 scale 7.6±1.9 6.2±3.9 Reasons for stopping, n (% contribution): Breathing discomfort 7 (70) 3 (60) Leg discomfort 1 (10) 1 (20) Combination 2 (20) 1 (20) Values represented number (percent) or mean±sd. BMI: body mass index; BDI: baseline dyspnoea index; FVC: forced vital capacity; FEV1: forced expiratory volume in 1 s; FRC: functional residual capacity; IC: inspiratory capacity; KCO: carbon monoxide transfer coefficient; MVV: maximal voluntary ventilation; O2 pulse: oxygen consumed per heart beat; PE,max: maximal expiratory pressure; PI,max: maximal inspiratory pressure; RER: respiratory exchange ratio; RV: residual volume; SpO2: peripheral oxygen saturation; TLC: total lung capacity; TLCO: transfer factor for carbon monoxide; V′CO2: carbon monoxide production; V′E: minute ventilation; V′E/V′CO2: ventilatory equivalent for carbon dioxide; V′O2: oxygen consumption.
- TABLE 2
Pre- and post-training assessments
IMT Control Between Pre Post Pre Post Mean dif. 95% CI TDI, score 6.2±1.2 3.2±2.6 3.0** 0.9–5.1 Exercise endurance time, min 6.4±2.8 12.4±6.4** 7.2±4.7 7.2±3.4 6.0* 0.4–11.5 Pulmonary function FEV1, L 2.1±0.5 2.5±0.8* 2.2±0.7 2.4±0.8 0.1 −0.2–0.5 FVC, L 3.0±0.5 3.6±0.8** 3.1±1.1 3.4±1.1* 0.3 −0.2–0.8 FVCsupine-FVCseated, % dif −29±9 −23±6 −24±8 −18±4 −12 −24–1 MVV, L 89±44 108±58* 78±17 85±18 8 −36–52 IC, L 2.6±0.5 3.1±0.8** 2.5±0.9 3.1±1.3* −0.1 −0.6–0.5 TLC, L 5.4±2.7 5.9±2.6 5.2±2.7 5.4±2.8* 0.7 −2.6–4.0 RV, L 2.3±1.2 2.3±1.0 2.1±1.0 2.1±1.0 0.2 −1.3–1.7 TGV, L 3.0±1.5 3.3±1.5 2.6±1.2 2.9±1.4 0.3 −1.5–2.2 Respiratory muscle strength PI,max, cmH2O 79±27 103±19** 88±23 84±21 28** 13–43 PE,max, cmH2O 221±96 219±81 198±103 190±92 4 −44–53 Pes,sniff, cmH2O −53±20 −66±22*** −52±16 −54±20 −10 −22–1 Pga,sniff, cmH2O −4±7 −6±6 −3±2 −5±6 0 −6–7 Pdi,sniff, cmH2O 49±17 60±22** 53±27 52±28 12* 0–23 Pga,cough, cmH2O 208±33 212±26 202±98 197±96 9 −15–32 Pdi,tw affected, cmH2O 1±1 3±3 3±3 6±4 0 −4–4 Pdi,tw unaffected, cmH2O 9±7 9±5 8±2 8±5 3 −3–8 Pdi,tw bilateral, cmH2O 10±6 10±7 9±2 9±3 −1 −6–4 Phrenic nerve conductance Latency, ms: Affected 14.3±7.7 13.4±7.1 10.5±5.9 10.2±5.6 0.9 −3.4–5.3 Unaffected 8.6±1.6 8.8±1.8 8.0±3.8 8.9±4.1 −0.6 −5.0–3.8 Amplitude, µV: Affected 143±150 182±163 100±55 300±217 −39 −255–178 Unaffected 495±221 630±200 450±321 575±472 35 −305–375 Values represent mean±sd or mean difference and the lower to upper limit of the 95% confidence interval. dif.: difference; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; IC: inspiratory capacity; IMT: inspiratory muscle training; MVV: maximal voluntary ventilation; Pdi,sniff: transdiaphragmatic pressure during a sniff manoeuvre; Pdi,tw: transdiaphragmatic pressure during a supramaximal potentiated twitch; PE,max: maximal expiratory pressure; Pes,sniff: oesophageal pressure during a sniff manoeuvre; Pga,sniff: gastric pressure during a sniff manoeuvre; Pga,cough: gastric pressure during a cough manoeuvre; PI,max: maximal inspiratory pressure; RV: residual volume; TDI: transition dyspnoea index; TGV: thoracic gas volume; TLC: total lung capacity. *: p<0.05; **: p<0.01; ***: p<0.001.
- TABLE 3
Exercise responses at iso-time during constant work rate exercise pre- and post-training
IMT Control Between Pre Post Pre Post Mean dif. 95% CI Perceptual ratings Dyspnoea, 0–10 scale 7.4±2.0 5.1±3.0* 7.4±2.1 7.6±2.4 −2.6 −5.7–0.6 Leg effort, 0–10 scale 7.1±1.7 6.1±2.9 5.2±4.1 5.0±3.8 −0.8 −3.2–1.6 Breathing pattern VʹE, L·min−1 52.4±21.2 53.5±22.6 69.0±38.1 66.4±36.5 3.8 −3.4–11.0 fB, breaths·min−1 34±12 30±11 33±18 28±15 2 −6–10 VT, L 1.6±0.6 1.8±0.9 2.2±1.2 2.5±1.4 0 −0.6–0.5 Ti/Ttot, % 45±15 46±15 45±25 47±26 0 −6–6 PEFR, L·s−1 2.6±1.0 2.7±1.1 3.4±1.9 3.2±1.7 0.2 −0.3–0.7 IC, L 2.3±0.4 2.8±0.7** 2.6±0.9 2.9±1.0* 0.3 −0.2–0.6 Respiratory mechanics Pes, cmH2O −21±12 −15±7* −21±11 −20±11 6 −2–14 Pga,av, cmH2O −14±9 −9±4* −13±7 −11±7 4 −3–11 Pdi,av, cmH2O 7±5 6±4 8±5 9±7 −2 −6–2 Pga,rise, cmH2O 24±17 16±8* 21±12 20±14 −7 −19–5 EMGdi, % max 60±25 54±24 67±9 60±5 2 −7–11 EMGscm, % max 27±15 18±9 21±13 25±12 −13* −25–−1 EMGsca, % max 47±26 35±20 31±18 35±19 −16 −40–8 Respiratory muscle tissue oxygenation Δ StiO2,scm, % −13.5±8.5 −6.1±4.2* −5.6±7.8 −11.4±9.0 13.3* 0.2±26.4 Δ StiO2,sca, % −6.9±2.8 −8.4±5.8 −6.4±5.9 −8.2±10.6 0.3 −11.0±11.6 Δ StiO2,abd, % −7.1±3.5 −3.4±3.5* −5.2±1.2 −3.4±3.1 1.2 −3.4±5.8 Values represent mean±standard deviation or mean difference and the lower to upper limit of the 95% confidence interval. Δ StiO2,abd: change in tissue oxygenation index of the rectus abdominus from rest to iso-time; Δ StiO2,sca: change in tissue oxygenation index of the scalene from rest to iso-time; Δ StiO2,scm: change in tissue oxygenation index of the sternocleidomastoid from rest to iso-time; fB: breathing frequency; EMGdi: electromyography of the diaphragm; EMGsca: electromyography of the scalene; EMGscm: electromyography of the sternocleidomastoid; IC: inspiratory capacity; PEFR: peak expiratory flow rate; Pdi,av: average transdiaphragmatic pressure during inspiration; Pes,av: average oesophageal pressure during inspiration; Pga,av: average gastric pressure during inspiration; Pga,rise, average increase in gastric pressure during expiration; Ti/Ttot: ratio of inspiratory time for one breath to total time of one breath; V′E: minute ventilation; VT: tidal volume. *: p<0.05; **: p<0.01.
