The one repetition maximum test and the sit-to-stand test in the assessment of a specific pulmonary rehabilitation program on peripheral muscle strength in COPD patients

Figures & data

Table 1 Baseline characteristics of the two groups of COPD patients following SPR program and UPR program

	SPR group of patients (n=30)	UPR group of patients (n=30)	P-value
Age (years)	69±5.8	72±8	0.143
Sex, female (%)	5 (16.7)	6 (20)	0.738
BMI (kg/m^2)	25±4	26±5	0.165
Smoking (pack years)	53±31	58±36	0.571
FEV1 (% pred)	46±14	51±16	0.192
VC (% pred)	81±16	81±15	0.918
FEV1/VC (%)	40±12	44±12	0.269
RV (% pred)	191±48	176±46	0.211
TLC (% pred)	129±20	125±25	0.540
RV/TLC (%)	61±9	60±8	0.793
TL,CO (% pred)	52±13	50±13	0.433
PaO2 (mmHg)	74±7	71±7	0.159
PaCO2 (mmHg)	37±4	38±5	0.234
Exacerbations previous year (n)	1.1±1.3	1.2±1.4	0.902
1-RM (kg)	33±7	30±10	0.212
1-minute STST (n)	24±4	23±5	0.237
30-second STST (n)	13±3	13±2	0.731
6MWT (m)	450±84	417±92	0.154

Notes: Values are expressed as mean ± SD or percent. Comparisons between variables were determined by unpaired t-test and χ² test. The two groups were matched for age, sex, and disease severity.

Abbreviations: SD, standard deviation; FEV₁, forced respiratory volume in 1 second; VC, vital capacity; RV, residual volume; TLC, total lung capacity; TL,CO, transfer factor of the lung for carbon monoxide; BMI, body mass index; PaO₂, arterial partial pressure of oxygen; PaCO₂, arterial partial pressure of carbon dioxide; 1-RM, one-repetition maximum; STST, sit-to-stand test; 6MWT, 6-minute walking test; pred, predicted; SPR, specific pulmonary rehabilitation; UPR, usual pulmonary rehabilitation.

Table 2 Relationship between baseline variables and the three outcomes of peripheral muscle strength, 30-second STST and 1-minute STST and 1-RM, in all study patients

	30-second STST	1-minute STST	1-RM
Age (years)	r=−0.21; P=0.104	r=−0.22; P=0.091	r=−0.25; P=0.052
BMI (kg/m^2)	r=0.08; P=0.521	r=−0.01; P=0.940	r=0.21; P=0.102
Exacerbations previous year (n)	r=0.01; P=0.914	r=−0.04; P=0.765	r=−0.15; P=0.267
Pack years (n)	r=−0.01; P=0.991	r=−0.12; P=0.352	r=−0.11; P=0.414
FEV1 (% pred)	r=0.38; P=0.002	r=0.46; P<0.001	r=0.38; P=0.002
VC (% pred)	r=0.37; P=0.003	r=0.48; P<0.001	r=0.37; P=0.003
FEV1/VC	r=0.26; P=0.044	r=0.31; P=0.015	r=0.24; P=0.061
RV (% pred)	r=−0.24; P=0.062	r=−0.14; P=0.304	r=−0.13; P=0.341
TLC (% pred)	r=0.09; P=0.497	r=0.23; P=0.078	r=−0.22; P=0.086
RV/TLC	r=−0.36; P=0.004	r=−0.26; P=0.042	r=−0.49; P<0.001
TL,CO (% pred)	r=0.13; P=0.323	r=0.38; P=0.003	r=0.27; P=0.035
PaO2 (mmHg)	r=0.11; P=0.388	r=0.27; P=0.039	r=0.03; P=0.809
PaCO2 (mmHg)	r=−0.06; P=0.629	r=−0.12; P=0.356	r=−0.16; P=0.228

Notes: Relationships between variables were assessed by the Pearson’s correlation coefficient (r). Values in bold type significant correlations.

Abbreviations: FEV₁, forced respiratory volume in 1 second; VC, vital capacity; RV, residual volume; TLC, total lung capacity; TL,CO, transfer factor of the lung for carbon monoxide; BMI, body mass index; PaO₂, arterial partial pressure of oxygen; PaCO₂, arterial partial pressure of carbon dioxide; 1-RM, one-repetition maximum; STST, sit-to-stand test.

Figure 1 Relationship between the 1-RM and the two STSTs, 30-seconds (r=0.48, P<0.001) (A) and 1-minute (r=0.36, P=0.005) (B) at baseline in 60 COPD patients.

Abbreviations: STST, sit-to-stand test; 1-RM, one-repetition maximum.

Figure 2 Plot of the percentage difference between 1-RM and 30-second STST against the mean of 1-RM and 30-second STST (A), and plot of the percentage difference between 1-RM and 1-minute STST against the mean of 1-RM and 1-minute STST (B) in 60 COPD patients.

Abbreviations: STST, sit-to-stand test; 1-RM, one-repetition maximum.

Table 3 Comparisons between the two STSTs and 1-RM with respect to VAS fatigue at the end of the test, HR, SpO₂, and time required to complete the test

	30-second STST	1-minute STST	1-RM	P-value§	P-value#	P-value*
VAS fatigue	40±26	58±26	50±29	0.047	0.122	<0.001
HR at rest (bpm)	83±13	83±13	82±13	0.620	0.847	0.765
HR max (bpm)	101±13	99±15	92±14	<0.001	0.013	0.382
∆HR (bpm)	18±9	16±11	10±8	<0.001	<0.001	0.412
SpO2 at rest	95±2	94±2	94±2	0.003	0.713	0.009
SpO2 (min)	93±2	92±3	92±2	0.019	0.428	0.003
∆SpO2	2±1.8	2.6±2	2±1.5	0.911	0.103	0.157
Time (sec)	120±32	164±46	491±145	<0.001	<0.001	<0.001

Notes: Values are expressed as mean ± SD. Comparisons between variables were determined by ANOVA, followed by the Student’s t-tests with Bonferroni adjustment.

§ 30-second STST vs 1-RM;

# 1-minute STST vs 1-RM;

* 30-second STST vs 1-minute STST.

Abbreviations: 1-RM, one-repetition maximum; STST, sit-to-stand test; 6MWT, 6-minute walking test; VAS, visual analogic scale; HR, heart rate; SpO₂, oxygen saturation; SD, standard deviation; vs, versus; ∆HR, change after test in heart rate; ∆SpO₂, oxygen saturation.

Table 4 Response to PR in the COPD patients following the SPR program and the UPR program

Outcome	SPR group (n=30)			UPR group (n=30)
	Pre-PR	Post-PR	P-value	Pre-PR	Post-PR	P-value
1-RM (kg)	33±7	43±13	<0.001	30±10	32v10	0.086
1-minute STST (n)	24±4	26±6	0.005	23±5	24±7	0.111
30-second STST (n)	13±3	15±3	<0.001	13±2	14±3	0.042
6MWT (m)	450±84	479±89	0.001	417±92	454±8	0.001

Notes: Values are expressed as mean ± SD. Comparisons between variables were determined by paired t-test.

Abbreviations: 1-RM, one-repetition maximum; STST, sit-to-stand test; 6MWT, 6-minute walking test; PR, pulmonary rehabilitation; SD, standard deviation; SPR, specific pulmonary rehabilitation; UPR, usual pulmonary rehabilitation.