Date Presented 03/31/2022

OTs frequently experience low back pain secondary to patient handling tasks. Different bed heights have been shown to elicit different low back and hand forces, but the full range of bed heights has never been explored. This study observed low back and hand forces using a full range of bed heights and found that higher bed heights reduce the forces necessary when performing a patient boosting task, thereby reducing the overall stress on the bodies of OTs.

Primary Author and Speaker: Robert E. Larson

Contributing Authors: Spencer R. Peterson, Lauren W. Adams, A. Wayne Johnson, Ulrike H. Mitchell

PURPOSE: Repositioning patients is a frequent task for occupational therapists, which causes substantial stress to the low back. This is particularly true when working with patients who require a greater level of assistance. Patient handling methodologies that reduce the load placed on the low back should be sought and used. Some studies have observed the effect of bed height on low back forces using a limited range of bed heights that are standardized to the participant’s height. This study detailed a wider range from the lowest possible bed height to the highest possible bed height for the adjustable hospital bed used. The purpose of this study was to discover an optimal bed height as a percentage of participant height for reducing low back and hand forces when boosting a patient up in bed with the assumption that higher bed heights would require less force than lower heights.

DESIGN: This study used a quasi-experimental design with a convenience sample of 11 university students and community volunteers to complete a series of boosts. A 202-lb research assistant acted as a dependent patient while a second, consistent researcher assisted with the boosting task.

METHOD: Three boosts were completed at each bed height at intervals of 3% of participant height until the bed maxed out (bed height ranged from 22-38 inches) which resulted in 8-10 different bed heights depending on the height of the participant. A Qualysis motion capture system was used to collect joint angles and 2 AMTI in-ground force plates collected force data. These data were used together to calculate hand forces and estimate low back forces, which was done using custom MATLAB code and 3DSSPP. Correlational analysis was performed to observe the relationship between percent caregiver height and hand and low back forces.

RESULTS: There was a significant negative correlation between bed height and low back compression force at L4-L5 (r = -0.676, p = <.001) and L5-S1 (r = -0.704, p = <.001). There were no significant correlations between any of the shear forces with bed height. There was also no significant correlation between calculated hand force and bed height.

CONCLUSION: The highest bed height led to the minimum low back compression forces regardless of participant height, but there was not a significant increase in shear forces in the anterior/posterior or lateral directions. Thus, occupational therapists should experience less low back stress with the bed at a higher height. In this study the highest the bed reached was the waist level of the shortest participants, thus the level of the waist is recommended to decrease low back force based on the data presented here. It could be enlightening to include higher bed heights in the future with a bed that has a wider range. There might also be a force tradeoff between the low back and other parts of the body that needs further exploration.

IMPACT STATEMENT: Occupational therapists should adjust the bed to waist height, or the highest position of the bed if waist height is unattainable, prior to boosting tasks to reduce the amount of force at the low back, which is the primary site of injury in healthcare workers. This can increase the longevity of the careers of occupational therapists that work with more dependent populations.


Lindbeck, L., & Engkvist, I.-L. (1993). Biomechanical analysis of two patient handling tasks. International Journal of Industrial Ergonomics, 12(1), 117-125.

Marras, W., Davis, K., Kirking, B., & Bertsche, P. (1999). A comprehensive analysis of lowback disorder risk and spinal loading during the transferring and repositioning of patients using different techniques. Ergonomics, 42(7), 904-926.

Murtagh, E. M., & Rice, M. S. (2015). Required caregiver forces while sliding a patient up in bed using a variety of bed heights. [Published doctoral scholarly project, The University of Toledo]. University of Toledo.

Rice, M. S., Dusseau, J. M., & Kopp Miller, B. (2011). A Questionnaire of Musculoskeletal Injuries Associated with Manual Patient Lifting in Occupational Therapy Practitioners in the State of Ohio. Occupational Therapy in Health Care, 25(2-3), 95-107.