Influence of coronary artery disease on cardiolocomotor coupling during walking: a preliminary study

Figures & data

Table 1. Characteristics of the study participants.

Characteristics	CAD group	Control group	p value
Age (years)	59 (15)	66 (3)	ns
Height (cm)	166.6 (6.4)	168.4 (9.4)	ns
Weight (kg)	63.4 (16.9)	62.9 (8.8)	ns
Body mass index (kg/m^2)	22.8 (5.6)	22.1 (1.3)	ns
Normal walking speed (km/h)	4.45 (0.52)	3.96 (0.42)	ns
Smoking history (Current/Past/None)	0/4/4	0/6/2

Data represent mean (standard deviation).

CAD, coronary artery disease; ns, not significant (Student’s t-test).

Table 2. Medical and treatment characteristics of the CAD group.

Characteristics	Patients (n)
Diagnosis
Acute myocardial infarction	6
Angina pectoris	2
Immediate treatment
Percutaneous coronary intervention	6
Coronary artery bypass grafting	2
Comorbidities
Dyslipidemia	7
Hypertension	6
Diabetes	2
Medication status
Beta-blocker	8
ARB	3
Statins	7
Oral anticoagulant	8
ACE inhibitor	2

ACE inhibitor: angiotensin-converting enzyme inhibitor; ARB: angiotensin II receptor antagonist; CAD, coronary artery disease.

Table 3. Comparison of strength of cardiolocomotor coupling and cardiopulmonary exercise testing data.

Variable	CAD group	Control group	Sig.
Walking test data
R^2 value	0.67 (0.17)	0.33(0.26)	*
R–R interval (ms)
At start	814.3 (88.0)	759.9 (55.8)
At normal walking speed	675.6 (83.7)	679.1 (60.8)
Step interval (ms)
At start	1024.3 (291.6)	1000.6 (216.3)
At normal walking speed	590.2 (79.2)	596.0 (57.1)
Cardiopulmonary exercise testing data
Resting SBP (mmHg)	109.9 (17.2)	116.8 (13.8)
Peak SBP (mmHg)	165.4 (20.3)	179.6 (13.5)
Resting DBP (mmHg)	73.6 (14.3)	75.1 (10.3)
Peak DBP (mmHg)	77.4 (19.9)	80.4 (9.4)
Resting HR (bpm)	72.1 (11.0)	68.1 (8.0)
Peak HR (bpm)	122.0 (20.4)	125.4 (11.6)
% Predicted peak HR (%)	76.1 (12.7)	81.3 (7.3)
Peak VO2 (mL/kg/min)	17.3 (1.9)	21.9 (3.9)	*
% Predicted peak VO2 (%)	69.4 (10.6)	91.3 (15.4)	*
VO2 at AT (mL/kg/min)	11.4 (1.6)	15.9 (3.5)	*
% Predicted VO2 at AT (%)	71.1 (10.5)	100.4 (21.3)	*
Peak work load (W)	90.5 (23.8)	113.0 (23.0)

Data represent mean (standard deviation).

*P < 0.05 compared with the CAD group (Student’s t-test).

Sig., significance indicator; CAD, coronary artery disease; R² value, index of strength of cardiolocomotor coupling; SBP, systolic blood pressure; DBP, diastolic blood pressure; HR, heart rate; VO₂, oxygen uptake; AT: anaerobic threshold.

Figure 1. Relationship between R–R intervals and step intervals of representative participants in the coronary artery disease (CAD) and control groups. The R–R interval and step interval during treadmill walking with progressive load are indicated as dots. The coefficient of determination (R² value) of the R–R interval and step interval represent the intensity of cardiolocomotor coupling. A and B indicate one representative from the CAD and control groups, respectively. A strong relationship can be observed between the R–R interval and step interval in A.

Figure 2. Relationship between the R² values and peak oxygen uptake in the coronary artery disease group. R² values represent the intensity of cardiolocomotor coupling. Figure 2 shows a significant negative rank correlation between peak oxygen uptake and R² values in the coronary artery disease group. Statistics are based on Spearman’s rank correlation coefficient test.

Data availability statement

The data that support the findings of this study are openly available in figshare at https://doi.org/10.6084/m9.figshare.20205683.v2