Table 1.
Kinematic and model-derived data for the 12 younger and 8 older subjects at the instants of slip onset and recovery, and the peak values. The p-values are from independent t-tests comparing groups. The last column indicates the total number of subjects in each group for whom the peak value of the variable occurred at the instant of recovery.
| Young | SD | Old | SD | p (young vs. old) | N (young, old) whose peak occurred at recovery | |
|---|---|---|---|---|---|---|
| At slip onset | ||||||
| Slip-side shoulder flexion angle (deg) | −16.8 | 16.3 | −11.3 | 9.9 | 0.405 | |
| Rec-side shoulder flexion angle (deg) | 7.5 | 11.2 | 5.9 | 8.1 | 0.728 | |
| Slip-side shoulder flexion velocity (deg/s) | −4.0 | 36.7 | −28.7 | 34.0 | 0.147 | |
| Rec-side shoulder flexion velocity (deg/s) | −34.8 | 24.4 | −33.0 | 19.7 | 0.867 | |
| Trunk extension (deg) | 4.7 | 6.0 | −1.7 | 3.2 | 0.014* | |
| Trunk extension velocity (deg/s) | 16.3 | 13.4 | 22.6 | 13.2 | 0.311 | |
| Peak values | ||||||
| Slip-side shoulder flexion velocity (deg/s) | 164.8 | 166.7 | 95.4 | 54.8 | 0.434 | (0, 0) |
| Rec-side shoulder flexion velocity (deg/s) | 129.8 | 122.5 | 82.6 | 144.2 | 0.564 | (9, 3) |
| Trunk extension (deg) | 11.9 | 7.2 | 4.5 | 5.8 | 0.025* | (12, 6) |
| Trunk extension velocity (deg/s) | 88.7 | 34.1 | 82.9 | 43.7 | 0.744 | (4, 6) |
| ωTpeak (deg/s) | 95.0 | 34.3 | 86.7 | 44.4 | 0.645 | |
| ΔωTmax (deg/s) | 13.5 | 10.8 | 8.1 | 7.6 | 0.239 | |
| ΔωTmax (%) | 13.6 | 11.4 | 10.4 | 13.3 | 0.592** | (2, 2) |
| At recovery | ||||||
| Slip-side shoulder flexion angle (deg) | 2.1 | 25.4 | −0.8 | 8.5 | 0.713 | (8, 7) |
| Rec-side shoulder flexion angle (deg) | 2.7 | 17.5 | 0.4 | 20.4 | 0.794 | (4, 2) |
| Slip-side shoulder flexion velocity (deg/s) | 75.9 | 147.8 | 40.9 | 186.6 | 0.751 | |
| Rec-side shoulder flexion velocity (deg/s) | 87.4 | 164.0 | 57.0 | 89.2 | 0.563 | |
| Trunk extension (deg) | 11.9 | 7.2 | 4.4 | 5.9 | 0.024* | |
| Trunk extension velocity (deg/s) | 77.0 | 41.9 | 82.2 | 44.0 | 0.793 | |
| ωT(recovery) (deg/s) | 80.4 | 41.9 | 84.3 | 45.6 | 0.849 | |
| ΔωT(recovery) (%) | 12.4 | 27.2 | 5.3 | 10.8 | 0.876 | |
difference between younger and older subjects is significant (p<0.05)
when one older subject statistical outlier is removed from the data set, this value becomes p=0.045 and the theoretical reduction in trunk extension velocity, expressed as a percentage, decreases to 5.8% (SD: 3.4)
ωT0 is the theoretical peak trunk extension velocity in the absence of arm motion
ΔωTmax = ωT0 - [peak trunk extension velocity]
ωT(recovery) is the theoretical recovery trunk extension velocity in the absence of arm motion
ΔωT(recovery) = ωT(recovery) - [recovery trunk extension velocity]