Table 1.
Baseline Demographics of Study Population (N = 457)
| Characteristic | Overall (SD / %) | Normal Cost (SD / %) | High Cost (SD / %) | p Value |
|---|---|---|---|---|
| N = 457 | n = 182 | n = 275 | ||
| Age (y) | 70.3 (10.3) | 67.0 (9.8) | 72.2 (9.9) | <.001 |
| Male sex (no.) | 233 (51.0%) | 79 (43.6%) | 154 (56.1%) | .008 |
| Height (cm) | 169.4 (9.2) | 169.1 (9.0) | 169.6 (9.4) | .48 |
| Weight (kg) | 77.1 (15.3) | 78.1 (16.3) | 76.5 (14.7) | .30 |
| Fat mass (kg) | 26.7 (10.0) | 28.0 (10.4) | 25.9 (9.6) | .03 |
| Lean mass (kg) | 47.6 (9.8) | 47.1 (9.7) | 47.9 (9.8) | .33 |
| Non-White race | 146 (32.5%) | 74 (40.3%) | 72 (25.3) | .001 |
| Usual gait speed (m/s) | 1.07 (0.2) | 1.08 (0.2) | 1.06 (0.2) | .33 |
| Walking O2 consumption (mL/minute) | 973.6 (252.0) | 855.6 (244.1) | 1050.2 (239.5) | <.001 |
| Walking CO2 production (mL/minute) | 786.7 (210.7) | 694.9 (180.5) | 846.4 (207.7) | <.001 |
| Walking O2 consumption per kg (mL/kg/minute) | 12.5 (2.5) | 10.8 (1.8) | 13.7 (2.3) | <.001 |
| Energetic cost of walking (mL O2/kg/m) | 0.17 (0.03) | 0.14 (0.01) | 0.19 (0.02) | <.001 |
| Smoking (no.)a | 9 (1.9%) | 3 (1.6%) | 6 (2.1%) | .71 |
| Cardiovascular disease (no.)b | 56 (12.3%) | 17 (9.4%) | 39 (14.0%) | .12 |
| Cerebrovascular disease (no.)c | 21 (4.6%) | 8 (4.8%) | 13 (4.7%) | .73 |
| Pulmonary disease (no.)d | 19 (4.2%) | 7 (3.7%) | 12 (4.4%) | .37 |
| Diabetes (no.)e | 37 (8.1%) | 15 (8.5%) | 22 (8.0%) | .81 |
| Arthritis (no.)f | 175 (38.3%) | 62 (34.0%) | 113 (41.1%) | .11 |
| Poor balanceg | 49 (10.7%) | 16 (8.8%) | 33 (11.8%) | .32 |
Notes. aSelf-reported history of smoking on a regular basis.
bSelf-reported history of heart disease or cardiac surgery, including myocardial infarction, congestive heart failure, angina pectoris, coronary artery bypass graft, and angioplasty.
cSelf-reported history of stroke or transient ischemic attack.
dSelf-reported history of pulmonary disease.
eSelf-reported past diagnosis of and current medication for diabetes.
fSelf-reported lower extremity arthritis pain.
gReported difficulty keeping balance when walking on a level surface.