| Carrying items is essential to everyday living, but is often reported to be a functional limitation in individuals with respiratory dysfunction. The interaction between breathing and carrying a bimanual load is not well understood and limits the capacity to derive interventions to address functional limitations. The purpose of this study was to examine the effect of two bimanual loads, 10% and 5% of body weight, on muscle activation of accessory breathing muscles, gait, and posture. Fourteen healthy, young adults stood and walked with and without a load on each wrist (2.5 and 5% of body weight) using wrist weights. The trapezius increased activation significantly as load increased, in both standing and walking. Posture became less regular in the anterior-posterior direction as load increased from baseline to 5% but decreased at 10%. Other linear measures, like sway path distance increased as load increased. While walking, step width mean and variability was altered significantly with load. The mean step width significantly decreased across all walking conditions as load increased. Whereas, the step width coefficient of variation significantly increased as load increased between all conditions. Step width measures have been linked to an increase in active control, suggesting that even a healthy young population required additional cognitive control during load carrying. It was expected that additional accessory muscles would be affected by load other than the trapezius group, but these results showed that healthy young adults are able to adjust to the difference in load without much change to the muscle activation pattern. Overall, carrying bimanual loads had a significant effect on muscle activation, gait, and posture in healthy, young adults. If healthy young adults displayed modifications at just 5%, 2.5% for each limb, than healthy older adults may show even more change. Further exploration of this topic is warranted to understand how a bimanual load effects other populations. |
