Time-Course of Changes in Multidimensional Fatigue and Functional Exercise Capacity and Their Associations during a Short Inpatient Pulmonary Rehabilitation Program

Figures & data

Figure 1. Flowchart of the study.

Table 1. Descriptive characteristics of the sample.

Variables	Mean/median	Standard deviation/[LQ-UQ]
Demographic and anthropometric
Age (years)	64.8	7.3
Sex (M/F)	37/33 (52.9%/47.1%)	–
Weight (kg)	74.4	[65.8–91.0]
Height (cm)	165.5	[163.0–173.0]
BMI	27.8	6.09
Pulmonary function
FEV1 (litre)	1.26	[0.95–1.69]
FEV1 (% predicted)	51	[36–70]
FEV1/FVC (%)	52	[40.7–60.4]
TLC (L)	7.1	1.6
TLC (% predicted)	120.6	20.5
GOLD stage 1 n (%)	6 (9%)	–
GOLD stage 2 n (%)	29 (41%)	–
GOLD stage 3 n (%)	23 (33%)	–
GOLD stage 4 n (%)	12 (17%)	–

BMI: body mass index; FEV1: forced expiratory volume in one second; FVC: forced vital capacity; TLC: total lung capacity; GOLD: global initiative for chronic obstructive lung disease; LQ: lower quartile; UQ: upper quartile.

Figure 2. Change in the 6-minute walking distance (A) and the total fatigue MFI-20 score (B), before (T0) and at the end of the 1^st (T1), 2^nd (T2), 3^rd (T3), and 4^th (T4) week of pulmonary rehabilitation. ***, **, *: significantly different with p < 0.001, 0.01, and 0.05, respectively. ns and ns*: not significantly different and p < 0.05 but not significantly different after Bonferroni correction, respectively. The data are means ± SD.

Table 2. Associations and changes in the associations between functional exercise capacity and fatigue markers.

Variables	T0	T1	T2	T3	T4
MFI-20 subscores
MFI-20gen	13.3 (3.3)	11.3 (3.3)*^#	10.7 (3.4)*	10.7 (3.2)*	10.2 (3.1)*
MFI-20phy	13.8 (3.4)	11.6 (3.4)*^#	10.6 (3.2)*^#	10.5 (3.2)*	10 (3.3)*
MFI-20men	9.9 (3.3)	9.2 (3.4)	8.5 (2.8)*	8.9 (3.1)	8.7 (3.2)*
MFI-20motiv	10.2 (2.9)	9.1 (3.1)*^#	8.4 (2.9)*	8.4 (2.7)*	8.4 (2.8)*
MFI-20act	12.4 (3.4)	10.8 (2.5)*^#	10.4 (2.7)*	10.5 (2.4)*	10.4 (2.5)*
Reaction time
Mean RT, ms	351.4 (46.7)	332.9 (38.9)*^#	333.1 (44.8)*	334.5 (45)*	333.7 (42.5)*
HRV data
RMSSD, ms	27.2 (12.8)	29.5 (13)	28.8 (15.3)	29.1 (14.7)	30.5 (16.8)
SDNN, ms	16.7 (10.9)	20.3 (12.1)	18 (13.1)	19.1 (14.2)	20.5 (14.9)
LF power, ms^2	69.7 (95.9)	73.2 (95.1)	62.5 (76.6)	67.4 (76.2)	69.2 (93.8)
HF power, ms^2	36 (52.7)	45.5 (52.2)	32.1 (46.1)	41.3 (59.1)	45 (67.7)
LF power, %	68 (19)	62 (19)	69 (17)	65 (20)	65 (20)
HF power, %	32 (19)	38 (19)	31 (17)	35 (20)	35 (20)
LF/HF	3.19 (2.41)	2.47 (2.25)	3.3 (2.34)	3.5 (3.95)	3.49 (3.91)

MFI-20_gen: General Fatigue; MFI-20_phy: Physical Fatigue; MFI-20_men: Mental Fatigue; MFI-20_motiv: Reduced Motivation; MFI-20_act: Reduced Activity; RT: reaction time; RMSSD: root mean square of R-R intervals; SDNN: standard deviation of normal-to-normal intervals; LF: low frequency; HF: high frequency. *Significantly different from T0 and ^#significantly different from preceding time. Data are mean ± SD.

Figure 3. Correlations between the 6-minute walking distance (on the y-axis) and the total fatigue MFI-20 score (on the x-axis) before (T0) and at the end of the 1^st (T1), 2^nd (T2), 3^rd (T3), and 4^th (T4) week of pulmonary rehabilitation. *: correlation coefficient significantly different from T0, T1, T2, and T4.

Data availability statement

Data are available upon request by mailing to the corresponding author