. 2014 May 1;9(5):e96574. doi: 10.1371/journal.pone.0096574

Table 3. Peak symptom-limited incremental treadmill exercise.

	GOLD 1	GOLD 2	Control
	n = 41	n = 63	n = 104
Work rate (W)	116±42^***	106±31^***	196±67
Dyspnea Borg scale^†	5.6±2.5	5.5±2.4	5.0±2.8
Leg discomfort Borg scale^†	4.7±2.8	5.3±2.6	4.7±2.8
(L/min)^†	1.81±0.59^***	1.62±0.41^*** ^, ^#	2.17±0.70
(L/min)^†	1.94±0.71^***	1.69±0.47^*** ^, ^#	2.46±0.79
^†	35.3±6.6^***	33.8±12.1^**	29.3±3.9
^†	67.1±23.6	55.1±15.4^*** ^, ^###	71.5±23.4
Breathing reserve (L/min)^†	25.6±15.4^***	9.6±14.3^*** ^, ^###	37.3±19.9
(%)^†	72±14	87±20^*** ^, ^###	66±16
Vt (L)^†	1.92±0.59^***	1.57±0.44^*** ^, ^###	2.17±0.66
Fb (breaths/min)^†	35.4±7.6	35.7±7.3	33.4±6.6
Ti/Ttot ^†	0.44±0.05	0.41±0.06^*** ^, ^##	0.45±0.06
IC (L)	2.67±0.78^**	2.17±0.59^*** ^, ^###	2.90±0.81
ΔIC peak–rest (L)	–0.52±0.44^***	–0.42±0.31^***	0.01±0.39
IRV (L)^†	0.75±0.40	0.60±0.40^*	0.73±0.36
EELV (L)	4.00±1.11^***	3.85±0.87^***	2.87±0.78
SpO₂minimum (%)^†	94.4±2.8	93.5±2.9^**	94.9±2.7

Data are presented as mean ± standard deviation.

GOLD, Global Initiative for Chronic Obstructive Lung Disease; Inline graphic , oxygen uptake; , carbon dioxide production; , minute ventilation; MBC, maximum breathing capacity; Vt, tidal volume; Fb, breathing frequency; Ti, inspiratory time; Ttot, total respiratory time; Ti _/Ttot, inspiratory duty cycle; IC, inspiratory capacity; Δ, change; IRV, inspiratory reserve volume; EELV, end-expiratory lung volumes; SpO₂, arterial oxygen saturation measured by pulse oximetry.

P-values are from a linear regression model, adjusted for age, sex, alcohol status, employment status, and body mass index.

*p<0.05 versus control;

**p<0.01 versus control;

***p<0.001 versus control

p<0.05 GOLD 1 versus GOLD 2;

^##

p<0.01 GOLD 1 versus GOLD 2;

^###

p<0.001 GOLD 1 versus GOLD 2.

^†

GOLD 2, n = 62.