Table 2.
Trial lookup.
| Trial # | Speed | Step length | Step frequency | Step width | Walking condition |
|---|---|---|---|---|---|
| 1 | 0.70 m·s−1 | 1.00 s* | 0.56 f* | Self-selected | Variable speed |
| 2 | 0.70 m·s−1 | Self-selected | Self-selected | Self-selected | Preferred walking |
| 3 | 0.70 m·s−1 | 0.56 s* | 1.00 f* | Self-selected | Variable step length |
| 4 | 0.90 m·s−1 | 1.00 s* | 0.72 f* | Self-selected | Variable speed |
| 5 | 0.90 m·s−1 | Self-selected | Self-selected | Self-selected | Preferred walking |
| 6 | 0.90 m·s−1 | 0.72 s* | 1.00 f* | Self-selected | Variable step length |
| 7 | 1.10 m·s−1 | 1.00 s* | 0.88 f* | Self-selected | Variable speed |
| 8 | 1.10 m·s−1 | Self-selected | Self-selected | Self-selected | Preferred walking |
| 9 | 1.10 m·s−1 | 0.88 s* | 1.00 f* | Self-selected | Variable step length |
| 10 | 1.60 m·s−1 | 1.28 s* | 1.00 f* | Self-selected | Variable step length |
| 11 | 1.60 m·s−1 | Self-selected | Self-selected | Self-selected | Preferred walking |
| 12 | 1.60 m·s−1 | 1.00 s* | 1.28 f* | Self-selected | Variable speed |
| 13 | 1.80 m·s−1 | 1.44 s* | 1.00 f* | Self-selected | Variable step length |
| 14 | 1.80 m·s−1 | Self-selected | Self-selected | Self-selected | Preferred walking |
| 15 | 1.80 m·s−1 | 1.00 s* | 1.44 f* | Self-selected | Variable speed |
| 16 | 2.00 m·s−1 | Self-selected | Self-selected | Self-selected | Preferred walking |
| 17 | 1.25 m·s−1 | 1.43 s* | 0.70 f* | Self-selected | Fixed speed |
| 18 | 1.25 m·s−1 | 1.25 s* | 0.80 f* | Self-selected | Fixed speed |
| 19 | 1.25 m·s−1 | 1.11 s* | 0.90 f* | Self-selected | Fixed speed |
| 20 | 1.25 m·s−1 | 1.00 s* | 1.00 f* | Self-selected | Multiple conditions |
| 21 | 1.25 m·s−1 | 1.00 s* | 1.00 f* | Self-selected | Multiple conditions |
| 22 | 1.25 m·s−1 | 1.00 s* | 1.00 f* | Self-selected | Multiple conditions |
| 23 | 1.25 m·s−1 | 0.91 s* | 1.10 f* | Self-selected | Fixed speed |
| 24 | 1.25 m·s−1 | 0.83 s* | 1.20 f* | Self-selected | Fixed speed |
| 25 | 1.25 m·s−1 | 0.77 s* | 1.30 f* | Self-selected | Fixed speed |
| 26 | 1.25 m·s−1 | 1.00 s* | 1.00 f* | 0.0 m | Variable step width |
| 27 | 1.25 m·s−1 | 1.00 s* | 1.00 f* | 0.1 m | Variable step width |
| 28 | 1.25 m·s−1 | 1.00 s* | 1.00 f* | 0.2 m | Variable step width |
| 29 | 1.25 m·s−1 | 1.00 s* | 1.00 f* | 0.3 m | Variable step width |
| 30 | 1.25 m·s−1 | 1.00 s* | 1.00 f* | 0.4 m | Variable step width |
| 31 | 1.40 m·s−1 | 1.00 s* | 1.12 f* | Self-selected | Variable speed |
| 32 | 1.40 m·s−1 | Self-selected | Self-selected | Self-selected | Preferred walking |
| 33 | 1.40 m·s−1 | 1.12 s* | 1.00 f* | Self-selected | Variable step length |
Most trials belong to one of five experimental conditions, and a few trials belong to multiple conditions. The preferred walking condition featured unconstraint walking, while other conditions had constraints on walking speed, step length, step frequency, or step width. The variable speed and variable step length conditions featured walking at various speeds with either step length or step frequency constrained to values preferred when walking at 1.25 m·s−1 (i.e., s* and f*, see Table 1). The fixed speed condition featured inversely varying combinations of step length and step frequency, while the variable step width condition featured various step widths at fixed speed, step length and step frequency. Trials 20–22 belong to all conditions, except for the variable step width condition.