Load handling: resting phases and changing posture
Taking steps to improve the work situation with regard to posture
Even with the constant changes in the world of work, a large proportion of employees continue to perform operational activities that are characterized by a high level of physical stress.
Against the background of the high proportion of back diseases, which are based on an imbalance in the relationship between mechanical loads and load-bearing capacity, it is necessary to subject workplaces to an appropriate risk assessment and to take appropriate steps in ergonomics and workplace design, prevention and rehabilitation.
Load handling and activities in forced postures often coincide and affect similar muscular groups and skeletal structures in the entire musculoskeletal system, but primarily the back. Permanently performing load handling in forced postures can lead to restrictions which make otherwise simple load handling seem impossible.
Performing manual activities in a forced posture
Definition - what is a forced posture (posture)?
It should be said in advance that both components (load handling and forced posture) must always be considered in a risk assessment. The two components (the handling of loads and the forced posture) are inextricably linked and the common trigger for the impairment of occupation.
Regular heavy lifting and transport of loads in what is known as a constrained posture pose health risks in all parts of the body. A forced posture is used in occupational medicine when an activity can only be carried out in this posture and a change in posture is practically impossible. A resting phase only occurs through changing activities.
If a load is handled in a “neutral” posture such as standing, walking or sitting upright, there are usually no direct consequences for a longer period of time. Muscle fatigue only occurs after hours of no rest. If, on the other hand, a posture has to be adopted during load handling, in which the trunk, arms or legs cannot be carried out in a “neutral” posture, without the possibility of a break or change of posture, symptoms of fatigue or impairments occur much earlier. Activities include, for example, lifting, carrying, pulling or pushing loads as well as repetitive manual activities or handling loads in a forced posture in the knees or in comparable forced postures.
Determination of loads during manual load handling
Careful observation of the posture
Manual handling of loads means lifting, lowering, carrying, transferring, holding, pushing, pulling or similar movement processes of goods using one’s own muscle power. As a result of this manual handling of loads, symptoms of muscle fatigue, general physical fatigue and musculoskeletal impairments and illnesses often occur, especially in the lumbar spine region and the adjacent muscle groups, but also in the shoulder-arm system.
For exposure to mechanical stresses when handling loads, it applies that the loads to be handled or the forces to be applied, the handling of the loads, the relationship between the center of gravity and the position of the loads, the direction of the forces acting on the object, the posture and movement of the When handling loads, the repetition frequency as well as the duration of the handling of loads and the load distribution and recovery phases in the context of each work cycle or each shift are designed to be gentle on the body.
The constructive framework conditions (e.g. range of motion, stability, working atmosphere, work clothing) and other criteria of physiological work design must also be taken into account.
The handling of loads can result in a variety of health impairments in the area of the back. The consequences of stress include both acute and chronic unspecific pain in the back. In addition, functional disorders and health impairments of the musculoskeletal system can be the result of accidents at work while handling loads, which generally entails an increased risk of accidents.
Adopting a forced physical posture
Avoidance of a back-damaging posture
A constrained physical posture is understood to mean a posture which, due to the activity to be performed, has to be assumed over a long period of time with few possibilities of movement. Working in the bend of the torso, kneeling, with the arms above shoulder or head level and lying down, forced sitting postures and standing for a long period of time without greater freedom of movement are the forced postures during load handling that can impair an employee. These postures result, among other things, in high static muscle loads, pressure effects on different tissue structures in the joints, and disorders of the intervertebral disc nutrition.
Parameters such as:
- The postures (trunk, neck or neck, upper and lower extremities)
- The forces to be applied
- The period and frequency of repetition of the stressful postures
- The distribution of work and rest times in relation to the work shift
Are essential for determining and assessing the respective stress caused by constrained postures.
If an activity at work is carried out over a longer period of time with a one-sided posture from the neutral position in walking, standing or sitting, this can cause static muscle stress. Activities such as bending the torso, kneeling and working above shoulder level should be minimized in terms of duration and repetition. You should often vary between sitting and standing so that you can change your posture and occasionally change your working position.
At all times, the body should move in a natural rhythm of movement and follow the natural movement paths. Identical and repetitive motion sequences should be avoided as they lead to impairments, complaints or injuries to employees. Load handling that requires high precision and accuracy should be carried out with little effort; aids (e.g. lifting gear and guides) are suitable for this in order to relieve the workload.
An evaluation and optimization of manual load handling
Determination of the forced posture during load handling with the help of Motion-Mining® technology
With the help of ergonomic analyzes as part of the MotionMining® solution approach, constrained postures can be discovered and optimized during load handling. By wearing wearables (portable sensors, similar to fitness trackers) during process analysis, it is now possible to distinguish between around 60 different movement sequences. Critical movements such as bending over from the back, carrying, lifting, holding, overhead activities are considered in the ergonomics analysis. These movements are recorded at movement intervals during the ergonomics analysis. In addition to the typical movements, vibrations and repetitions can also be specifically recognized. On the basis of the data from the ergonomics analysis, excessive and permanent loads can be identified and measures to avoid them can be derived. Work processes are automatically and anonymously recorded during the ergonomics analysis, processed using artificial intelligence (machine learning) and converted into human-readable key figures. On the basis of the findings, we develop a catalog of measures to improve the workplace with regard to ergonomics, so that experienced employees can work longer in their professions without impairment.