Situational factors that influence overreaching on a ladder during a gutter clearing task among older adults

Abstract

Ladder falls from overreaching are a problem in older adults. Evidence suggests ladder use behavior to be dependent on interfacing user and environmental circumstances (i.e. situational factors). This study investigates the effects of situational factors (remaining debris, ladder position, time into task, hand dominant reach, reaching disposition) on reaching during a gutter clearing task on a ladder in 104 older adults. Reaching was quantified as the maximum lateral center of pressure (COP) displacement from the ladder's center. A reach was classified as an overreach when the COP displaced outside the ladder width, indicative of a ladder tip. Reaching disposition, remaining debris, ladder position, and the interaction of reaching disposition and remaining debris predicted 20% of the reaching variability during the ladder task. Overreaching was observed in 40% of participants accounting for 13% of all extended reaches (beyond ladder). This work can guide interventions on mitigating overreaching and improving ladder safety.

Keywords: Decision making; Ladder falls; Reaching.

Figure 1:

COP trace throughout one climb with COP above 0 corresponding to left reaching and below 0 corresponding to right reaching. Zero corresponds to the COP location being in the center of the ladder. Reaches can be seen as the local minimum/maximum of steps in the COP data. If the minimum/maximum COP for each ladder climb and side during a reaching attempted exceeded the threshold of ± 199 mm, the reach was classified as an overreach.

Figure 2:

Experimental apparatus highlighting the different situational factors of the gutter reaching task with a) showing remaining debris, a reach to the dominant side, and an early % time, b) showing a late % time and ladder position.

Figure 3:

Scatterplot of COP against reaching disposition for remaining debris (black circles) and no remaining debris (blue triangles). The equations for each line of best fit are displayed by the corresponding line.

Figure 4:

The distribution of reaches between predicted COP and actual COP values. The blue lined denotes the line of best fit. The R² value denotes the variability of reaching explained by the model.

Figure 5:

Individual regressions for the significant situational factors of reaching including a) % time, b) ladder position, c) reaching disposition, and d) remaining debris. Each regression denotes the overreaching threshold of 199 mm with a red dashed line. COP values above the overreaching threshold are reaches that would have likely resulted in the ladder tipping if not constrained to the testing apparatus. Continuous measures include the line of best fit (solid blue line) and the regression equation from the statistical model. All plots include the reaching variability explained (R²).