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Background: With cell phone use and ownership on the rise, daily circumstances often require individuals to divide attentional resources between walking and a cell phone-related task. This division of attention has been found to detrimentally effect task performance, making pedestrian cell phone usage an increasing safety concern. However, most studies have investigated the impact of dual-tasks on situational awareness and few have focused on tasks other than texting. Therefore, this study aimed to investigate the effect of various cell phone-related tasks on lower limb kinematics during walking.

Methods: Fourteen healthy, college-aged subjects completed gait analysis trials in five walking conditions, one single-task walking condition and four dual task conditions: Walk+Converse, Walk+Read (Simple), Walk+Read (Difficult), and Walk+Text. Subjects’ movements were recorded with a motion capture system and peak sagittal plane lower extremity joint angles, gait velocity, and stride length were calculated.

Results: Of the eight kinematic outcome measures analyzed, all but one revealed some significant (p < 0.05) differences between dual-task walking conditions. Gait velocity and stride length both decreased due to the addition of the dual tasking, with the magnitude of the reduction becoming more apparent with the increased difficulty of the cell phone-based task.

Conclusion: This study supports a fundamental change to gait kinematics in response to cell phone use while walking, with the magnitude of impact being directly related to the complexity of the secondary task. The significant changes to gait kinematics in complex dual-task situations could present a threat to balance.

The anterior and posterior iliac spine markers frequently used to define the pelvis, are commonly occluded during three-dimensional (3D) motion capture. The occlusion of these markers leads to the use of various tracking marker configurations on the pelvis, which affect kinematic results. The purpose of this investigation was to examine the agreement of CODA pelvis kinematic results when two different tracking marker configurations were used during roofing tasks. 3D motion data were collected on seven male subjects while mimicking two roofing tasks. Hip joint angles (HJAs) were computed using the CODA pelvis with two different tracking marker configurations, the trochanter tracking method (TTM), and virtual pelvis tracking method (VPTM). Agreement between tracking marker configurations was assessed using cross-correlations, bivariate correlations, mean absolute differences (MADs), and Bland–Altman (BA) plots. The correlations displayed no time lag and strong agreement (all $r>0.83$) between the HJA from the VPTM and TTM, suggesting the timing occurrence of variables are comparable between the two tracking marker configurations. The MAD between the VPTM and TTM displayed magnitude differences, but most of the differences were within a clinically acceptable range. Caution should still be used when comparing kinematic results between various tracking marker configurations, as differences exist.

Back pain can affect up to 65% of the American population and cost the health care system approximately fifty billion dollars each year. Due to the difficulty with recording spine/trunk movement, several methods and models exist. The myriad of methods and the need for understanding of spine/trunk motion has led to a lack in a ‘gold-standard’ of treatment for individuals with back pain. Therefore, the purpose of this study was to examine the effect of different activities of daily living on the kinematics of individual trunk segments in young adults to determine how common ambulatory tasks will alter trunk motion compared to level walking.

Young healthy adults completed, in a random order, four activities of daily living: level walking, obstacle crossing, stair ascent and descent using a previously validated model. Subjects were outfitted with a full body marker set which included a segmented trunk. Multi-segmented trunk angles between the three inferior segments, sacrum to lower lumbar [SLL], lower lumbar to upper lumbar [LLUL] and upper lumbar to lower thorax [ULLT], were calculated and compared between tasks. Peak flexion angles, instance of peak angle and range of motion were analyzed.

The overall hypothesis that different spine levels will have altered kinematics during various activities of daily living was supported. Stair descent had smaller peak flexion angles than obstacle crossing and stair ascent. The instance of peak angle were different depending on trunk angle and daily task. The most inferior trunk angle — Sacrum-to-Lower Lumbar — had the largest range of motion during all four tasks in all three (sagittal, frontal and transverse) planes of motion.

This study was able to show how various activities of daily living produce different motions in the three inferior segments of a multi-segmented trunk method. The results of this study are the first steps in understanding how the trunk responds on a daily basis and how those responses could lead to back pain.