Table 1.
Descriptive Statistics of the Study Population (N = 1,056)
| Parameter | Missing data, n | n (%) | Median (interquartile range) |
|---|---|---|---|
| Men | 515 (48.8%) | ||
| Age, years | 60 (49–69) | ||
| Weight, kg | 79 (69–90) | ||
| Height, cm | 169 (162–176) | ||
| BMI, kg/m2 | 27.3 (24.6–30.6) | ||
| BMI ≥ 30 kg/m2 | 298 (28.2%) | ||
| Smoking status | 2 | ||
| Never smokers | 404 (38.3%) | ||
| Former smokers | 485 (46.0%) | ||
| Current smokers | 165 (15.7%) | ||
| Physically activea | 870 (82.4%) | ||
| Myocardial infarction | 2 | 25 (2.4%) | |
| Atrial fibrillation | 8 | 54 (5.1%) | |
| Heart failure | 125 | 30 (3.2%) | |
| Fractional shortening below normalb | 324 | 2 (0.3%) | |
| Heart operation | 1 | 22 (2.1%) | |
| Pacemaker | 3 | 5 (0.5%) | |
| Previous pulmonary disease | 2 | 52 (4.9%) | |
| Chronic bronchitisc | 1 | 53 (5.0%) | |
| Asthma | 4 | 55 (5.2%) | |
| Maximum exercise duration, s | 536 (420–670) | ||
| Maximum power, W | 148 (132–196) | ||
| peak VO2, mL/min | 2 | 1,812 (1,482–2,292) | |
| VO2@AT, mL/min | 1,009 (867–1,204) | ||
| VO2@AT/peak VO2 reference, % d | 54.6 (47.1–63.7) | ||
| VO2@AT/peak VO2 reference < 45% d | 163 (15.4%) | ||
| RER@AT | 0.82 (0.77–0.86) | ||
| FEV1/FVC, % | 3 | 75.7 (71.4–79.7) | |
| FEV1/FVC < 70% | 199 (18.9%) |
Anamnestic data based on survey by professional interviewer. Continuous data are expressed as the median (25th; 75th quartile). Nominal data are given as percentages
a Volunteers were asked about their physical activity and categorized as “Physically active” in case of 1–2 h of activity per week in summer and winter
b The echocardiographic parameter “fractional shortening” was calculated as (left ventricular diastolic – systolic diameter [in cm]) × 100. Pathologic values were < 19% in males and < 21% in females
c Subgroups may overlap
d Predicted values were calculated according to Gläser S et al. [28] These were: peak VO2 in males = 254.76–22.69 × age [years] + 17.25 × height [cm] + 4.41 × weight [kg]; and peak VO2 in females = −54.74 – 9.81 × age [years] + 9.92 × height [cm] + 8.06 × weight [kg]
BMI Body mass index, peak VO2 Peak oxygen uptake, VO2@AT Oxygen uptake at the aerobic-anaerobic threshold, RER Respiratory exchange ratio, FEV1/FVC Forced expiratory volume in 1 s/forced vital capacity