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Summary of Stresses

Metabolic Stresses

The aerobic energy systems will provide the major source of energy for the Automotive Mechanic. This position requires a low to moderate level of aerobic activity to perform vehicle repair. The anaerobic energy system may be used in high intensity repair tasks, such as lifting tires to and from the wheel lugs, lifting parts to and from their proper location or using cheater to loosen or tighten nuts and bolts.

Structural Stresses

Spine –Significant loading of the spinal structures are likely in this position. Prolonged loaded and unloaded forward flexion, extension, lateral flexion and rotation of the spine are all movements required by the Automotive Mechanic. Forward flexed postures require no activity from the torso musculature, but increase asymmetrical disc compression and passive stretch on the posterior spinal ligaments and disc fibres. This can contribute to disc integrity problems as well as contributing to deconditioning of the torso support musculature. Lateral flexion and/or rotation with or without forward flexion (loaded or unloaded) will significantly increase the shear forces encountered by the discs, fibres and spinal ligaments.

Due to the vehicle and equipment engineering and the space limitations found in the shop, it is almost impossible for the Automotive Mechanic to use proper postural control and body positioning for most of the work they perform. With this in mind, the goal should be to minimize the time spent in these undesirable, high-risk postures and make good postural and movement choices whenever the situation presents itself.

Neck, Shoulders and Upper Extremity– vehicle maintenance and repair requires prolonged and repeated static and dynamic movements. The static and dynamic movements through the shoulder and upper extremity often require the rotator cuff muscle groups, upper trapezius and scalene muscles of the neck to maintain a significant load. Hand, air and power tool use (predominately dominant hand) will increase the static and dynamic loading of the forearm flexors, extensors, supinator, pronator teres and the pronator quadratus. Power and air tool use will also increase the vibration, jarring and compressive forces from the grip to the elbow and shoulder that may lead to over use tendon or nerve injuries.

Hips and Lower Extremities – Standing and walking on concrete and asphalt for the entire shift increase the compressive forces through the ankles, knee, hips and spine. The awkward positions required to access some parts and components do not allow the Automotive Mechanic to perform the required work from a stable base of support. This in turn will increase the risk of injury for all of the other structures.

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