An analysis was performed to estimate compression and shear loads on three motion segments of the lumbosacral spine in neutral and flexed torso postures. Eighty-seven lifting tasks were evaluated using a biodynamic lifting model for lifts starting at 0-, 22.5-, and 45-degree torso flexion. Results indicated that the compressive loading on the L5-S1 disk in the 22.5- and 45-degree torso flexion conditions were approximately double and triple those observed in the 0-degree condition. Shear reaction forces acted anteriorly in neutral and moderate flexion, but acted posteriorly in full flexion. Load rates were also dramatically affected by posture, with the load rate in the fully flexed posture being seven times greater than in the neutral posture. Analysis of the upper lumbar levels (L1-L2 and L3-L4) suggested significant shear forces; however, shear forces at L5-S1 remained moderate in all conditions. Results of this analysis will be used in a study examining the fatigue failure of lumbar motion segments when subjected to loads experienced at different angles of torso flexion.
We take your privacy seriously. You can review and change the way we collect information below.
These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. They help us to know which pages are the most and least popular and see how visitors move around the site. All information these cookies collect is aggregated and therefore anonymous. If you do not allow these cookies we will not know when you have visited our site, and will not be able to monitor its performance.
Cookies used to make website functionality more relevant to you. These cookies perform functions like remembering presentation options or choices and, in some cases, delivery of web content that based on self-identified area of interests.
Cookies used to track the effectiveness of CDC public health campaigns through clickthrough data.
Cookies used to enable you to share pages and content that you find interesting on CDC.gov through third party social networking and other websites. These cookies may also be used for advertising purposes by these third parties.