Table 1.
General characteristics
|
Total group |
HF-NMES |
LF-NMES |
Strength training |
P-value | |
|---|---|---|---|---|---|
| n = 24 | n = 9 | n = 7 | n = 8 | ||
| Sex (M/F) |
14/10 |
6/3 |
4/173 |
4/4 |
0.791 |
| Age (years) |
66 (61–68) |
64 (59–67) |
62 (59–67) |
71 (66–77) |
0.012 |
| Pulmonary function | |||||
| FEV1 (liters ) |
0.98 (0.78-1.05) |
1.01 (0.84-1.19) |
0.74 (0.60-0.84) |
1.00 (0.96-1.10) |
0.010 |
| FEV1 (% predicted) |
35 (29–51) |
34 (23–51) |
30 (20–38) |
46 (43–60) |
0.064 |
| FEV1/VC max (%) |
32 (24–43) |
31 (24–41) |
25 (24–29) |
42 (33–52) |
0.057 |
| DLCO (%) |
42 (36–55) |
41 (31–55) |
42 (34–61) |
46 (40–56) |
0.802 |
| RV (%) |
177 (136–235) |
190 (137–243) |
208 (172–260) |
146 (128–178) |
0.081 |
| Arterial blood gases |
|
|
|
|
|
| PaO2 (kPa) |
9.8 (8.8-10.8) |
9.0 (8.5-10.9) |
9.6 (8.5-9.9) |
10.3 (9.4-11.2) |
0.284 |
| PaCO2 (kPa) |
4.9 (4.7-5.5) |
5.4 (4.8-5.7) |
5.0 (4.7-5.6) |
4.8 (4.6-5.1) |
0.159 |
| SaO2 (%) |
96 (95–97) |
95 (95–97) |
95 (94–97) |
97 (96–98) |
0.166 |
| GOLD classification (I/II/III/IV) |
0/7/10/7 |
0/3/3/3 |
0/0/4/3 |
0/4/3/1 |
0.025 |
| GOLD classification (new) (A/B/C/D) |
0/3/0/21 |
0/2/0/7 |
0/0/0/7 |
0/1/0/7 |
0.427 |
| BMI (kg/m2) |
25.4 (22.2-29.8) |
25.4 (21.9-26.9) |
24.6 (23.5-30.3) |
26.9 (21.5-31.1) |
0.834 |
| FFMI (kg/m2) |
17.0 (15.8-18.5) |
16.9 (15.7-17.5) |
16.5 (15.7-18.8) |
17.4 (15.8-19.1) |
0.680 |
| Cardiopulmonary exercise test | |||||
| Peak load (watts) |
47 (35–57) |
51 (35–57) |
46 (41–62) |
44 (30–58) |
0.867 |
| Peak load (% predicted) |
33 (23–47) |
26 (23–39) |
38 (22–81) |
39 (23–63) |
0.481 |
| Peak VO2 ( ml/min) |
841 (710–987) |
751 (697–919) |
817 (734–1087) |
904 (699–1076) |
0.473 |
| Peak VO2 (% predicted) |
48 (33–73) |
31 (27–64) |
53 (40–90) |
52 (40–115) |
0.142 |
| Peak VE (liters) |
33 (29–39) |
38 (28–41) |
32 (25–35) |
35 (29–44) |
0.553 |
| Peak VE (% MVV) |
89 (78–107) |
84 (72–98) |
103 (95–119) |
81 (68–101) |
0.040 |
| Peak HR (bpm) |
104 (98–124) |
103 (98–122) |
126 (104–131) |
102 (90–109) |
0.080 |
| Peak HR (% predicted) |
71 (64–75) |
66 (64–73) |
75 (68–83) |
70 (63–72) |
0.186 |
| Dyspnea, end (points) |
7 (5–8) |
7 (5–7.5) |
7 (7–9) |
8 (5–9.5) |
0.526 |
| Fatigue, end (points) |
5 (3–7) |
5 (3.5-7.5) |
5 (3–7) |
4 (3–7) |
0.861 |
| Saturation, end (%) | 91 (89–95) | 93 (91–98) | 90 (89–91) | 94 (89–96) | 0.132 |
Values expressed as median (interquartile range) or numbers. Data are compared between HF-NMES, LF-NMES and strength training.
Abbreviations: HF-NMES = High-frequency transcutaneous neuromuscular electrical stimulation; LF-NMES = Low-frequency transcutaneous neuromuscular electrical stimulation; M = males; F = females; FEV1 = forced expiratory volume in one second; VC max = maximum vital capacity; DLCO = diffusion capacity of the lung for carbon monoxide; RV = residual volume; PaO2 = resting arterial oxygen tension; PaCO2 = resting arterial carbon dioxide tension; SaO2 = resting arterial oxygen tension; kPa = kilopascal; LTOT = long-term oxygen therapy; GOLD = Global Initiative on Obstructive Lung Diseases; BMI = body mass index; FFMI = fat free mass index; kg/m2 = kilogram per square meter; VO2 = oxygen uptake; tSaO2 = transcutaneous oxygen saturation; ml/min = milliliters per minute; % MVV = percentage maximal voluntary ventilation; bpm = beats per minute.