Why so static?
It’s not just the load that can be an issue when talking about back pain. Sustained or static postures can be a cause of back pain (and not necessarily due to lifting).
In these postures, the blood supply is impaired, and such as, waste products accumulate which can cause muscular pain. The blood supply is important as oxygen in the fresh blood supply assists with muscle recovery and reducing muscle fatigue, by removing waste.
In order to reduce the effects of sustained or static postures (including sitting), regular breaks with gentle movement is recommended. These posture breaks allow the muscles and joints to move within their regular range of motion without stress (such as additional weight when lifting). Gentle movement and stretching is also recommended, moving between sedentary roles such as a sitting to strenuous tasks such as heavy lifting to prepare the body for work.
It’s important to remember the spine should also move within its normal pain free range of motion occasionally to prepare the body for work. Why is this important? The blood vessels supplying the spine do not have valves and therefore require movement to produce appropriate blood flow. When a static posture is maintained, there is a reduced blood flow to the vertebral tissues. This can contribute to back pain in workers who are unable to complete normal spine movement throughout their workday.
As well as the type of posture, it’s also important to consider frequency of movement. Infrequent or occasional lifting, has been shown to cause more back pain compared to more consistent heavy work. One explanation is poorer work methods. Another, is workers go from a sedentary or non laborious role to lifting without allowing the body to prepare for work and adapt to the work demands of lifting. Should an employee be doing physical work, it’s always important that the body is prepared for the work task. Workers should aim to adopt sound postures, complete gentle movement through out the day as well as be encouraged to come forward with ideas to improve the physical work environment to make their tasks easier and more efficient.
Sustained postures: as a general guideline a sustained posture is a posture or force is held for more than 30 seconds at a time.
Static postures: holding the same posture or position. This posture increases the load or forces in the muscles and tendons, which can contribute to fatigue.
Reference: Worth D (2000) Moving in on Occupational Injury. Oxford: Butterworth Heinemann
Wood, D. (1987). Design and evaluation of a back injury prevention program within a geriatric hospital. Spine, 12, 77-81