Patients with coronary artery- or chronic obstructive pulmonary disease walk with mechanical inefficiency

Figures & data

Table I.  Individual anthropometric and physiological data for the groups.

	COPD	CAD	Healthy controls
Variables	Group (n=13)	Group (n=10)	Group (n=9)
Sex (men/women)	6/7	8/2	5/4
Age (yr)	60.6±7.4	63.5±6.5	60.3±10.3
Height (cm)	168.6±5.8	172.3±8.4	174.2±7.5
Mass (kg)	70.2±9.6	79.3±12.1	73.0±11.1
VO2peak
(L·min^−1)	1.60±0.22	2.23±0.47†††	2.60±0.39###*
(ml·kg^−1·min^−1)	23.1±5.3	27.9±3.6†	36.2±7.1##**
(ml·kg^0.75·min^−1)	66.4±13.1	85.1±22.0†	105.4±17.9##*
HRpeak (beats·min^−1)	172±5	163±5	176±6
VEpeak (L·min^−1)	46.71±7.14	86.14±19.76†††	87.54±15.77###
R	1.08±0.08	1.14±0.06	1.04±0.04
[La^−]b (mmol·L)	5.85±1.58	4.35±1.24†	6.08±1.33*
Wattpeak	108.9±20.9	154.8±38.0††	167.6±31.8###

Data is presented as mean and standard deviation. VO₂, Oxygen uptake, HR, Heart rate, V_E, Pulmonary ventilation, R, Respiratory exchange ratio. [La⁻]_b, blood lactate concentration after VO_2peak testing. *Significant differences (p<0.05) between healthy and CAD, **Significant differences (p<0.01) between healthy and CAD. #Significant differences (p<0.05) between healthy and COPD, ##Significant differences (p<0.01) between healthy and COPD, ###Significant differences (p<0.001) between healthy and COPD. †Significant differences (p<0.05) between CAD and COPD, ††Significant differences (p<0.01) between CAD and COPD, ††† Significant differences (p<0.001) between CAD and COPD.

Figure 1.  Comparison of mean mechanical efficiency (%) at 40 W workload during cycling and treadmill exercise. Vertical lines represent standard error (SE). *Significant differences (P<0.05) between healthy and CAD, **Significant differences (P<0.01) between healthy and CAD, #Significant differences (P<0.05) between healthy and COPD, ##Significant differences (P<0.01) between healthy and COPD.

Table II.  Physiological parameters at 40 W work loads during bicycle and treadmill exercise.

	COPD	CAD	Healthy controls
Variables	Group (n=13)	Group (n=10)	Group (n=9)
Sex (men/Woman)	6/7	8/2	5/4
Walking
VO2
(L·min^−1)	1.30±0.15	1.24±0.09	1.09±0.21*##
(ml·kg^−1·min^−1)	19.2±4.0	15.7±2.5†	15.4±4.5#
(ml·kg^−0.75·min^−1)	55.4±9.4	46.6±5.5†	44.6±11.6#
HR (beats·min^−1)	129±17	103±16	113±18#
VE (L·min^−1)	35.75±4.07	34.80±4.78	29.91±8.67#
VE/VO2	27.45±3.59	28.13±3.16	27.29±5.08
R	0.91±0.05	0.88±0.04	0.84±0.04**##
Cycling
VO2
(L·min^−1)	0.97±0.19	0.84±0.09†	0.88±0.13
(ml·kg^−1·min^−1)	13.5±2.4	10.8±1.8†	12.3±2.5
(ml·kg^−0.67·min^−1)	56.5±9.7	45.6±5.4††	50.2±9.4
HR (beats·min^−1)	115±18	93±16	99±15
VE (L·min^−1)	27.57±4.46	25.66±2.75	23.63±7.43
VE/VO2	28.55±4.06	30.67±3.35	26.37±4.55
R	0.87±0.06	0.92±0.05	0.84±0.04**###

Data are presented as mean and standard deviations. VO₂, Oxygen uptake, HR, Heart rate, V_E, Pulmonary ventilation, V_E/VO₂, Ventilatory equivalent, R, Respiratory exchange ratio, *Significant differences (p<0.05) between healthy and CAD, **Significant differences (p<0.01) between healthy and CAD. #Significant differences (p<0.05) between healthy and COPD, ##Significant differences (p<0.01) between healthy and COPD, ###Significant differences (p<0.001) between healthy and COPD., †Significant differences (p<0.05) between CAD and COPD, ††Significant differences (p<0.01) between CAD and COPD.