Upper Extremity and Lower Back Moments During Carrying Tasks in Farm Children

Abstract

<p>Farm youth commonly perform animal care tasks such as feeding and watering. The pur­pose of this study was to determine the effects of age, bucket size, loading symmetry, and amount of load on upper body moments during carrying tasks. Fifty-four male and female par­ticipants in four age groups (8–10 years, 12–14 years, 15–17 years, and adults, 20–26 years) participated in the study. Conditions included combinations of large or small bucket sizes, unilateral or bilateral loading, and load levels of 10% or 20% of body weight (BW). During bucket carrying, elbow flexion, shoulder flex­ion, shoulder abduction, shoulder external rotation, L5/S1 extension, L5/S1 lateral bend­ing, and L5/S1 axial rotation moments were estimated using video data. The 8–10 year-old group did not display higher proportional joint moments as compared with adults. Decreasing the load from 20% BW to 10% BW signifi­cantly decreased maximum normalized elbow flexion, shoulder flexion, shoulder abduction, shoulder external rotation, L5/S1 lateral bend­ing, and L5/S1 axial rotation moments. Carry­ing the load bilaterally instead of unilaterally also significantly reduced these six maximum normalized joint moments. In addition, modi­fying the carrying task by using smaller one-gallon buckets produced significant reductions in maximum L5/S1 lateral bending moments.</p>