Static muscle loading is when a muscle is contracting but resulting in no movement of that body part. Static muscle loading can be seen in many work activities, for example carrying an object. Whilst the legs are involved in the dynamic muscle activity (walking) the arms are often in a fixed (static) position whilst holding the object. Other static muscle activities are involved in maintaining postures for a period of time, for example:
- Using a computer mouse with an outstretched arm (shoulder and upper arm muscles)
- Leaning over a car bonnet to work on an engine, muscles that are working in a static way involve the back muscles (upper and lower), hamstrings, neck and shoulders
- Constantly gripping a knife when cutting meat (hand and fingers)
Static muscle loading can often contribute to soft tissue injuries. Static activity cause fatigue in the muscles and tendons. During the static position of the muscles blood supply is restricted, therefore restricting the supply of nutrients and oxygen and the removal of waste products such as lactic acid. The longer or more frequent the static loading occurs the greater risk of injury. The constant muscle tension can lead to swelling and pressure on nearby nerves and static loading with high forces can lead to tears in the muscle tissue.
How do you combat static muscle loading?
- Take regular postural breaks and perform stretches to increase blood flow to the muscles
- Rotate tasks regularly to incorporate dynamic activities in to your work day
- Ensure your work station is correctly setup to avoid any unnecessary static and awkward postures
- Keep your body healthy and fit