Spine models have historically focused on assessing individual work actions in terms of their strain. The focus was on the intervertebral disc pressure, and the calculation was inverse-dynamic, i.e. actual measured movements were analyzed using the models. The strain estimation in this approach is still correct today, but nothing is learned about the body's internal cause-effect relationships. Only basic external effect mechanisms have been uncovered: Long levers (away from the body, poor posture) and heavy loads were identified as risk factors.

Meanwhile, modern models have made a huge leap in terms of structural resolution. Muscles, ligaments, discs and joints drive the models actively and also passively. The simulation process is forward dynamic, i.e. all mentioned force generating structures generate the desired motion due to force laws. Since the force laws of the individual structures are known, it is possible to calculate critical load limits in each structure. During a simple flexion of the lumbar spine, detached from gravity, it was shown that considerable compressive forces are generated on the intervertebral disc. This occurs in force equilibrium (actio = reactio) with the dorsal ligaments. The bending of the back, as it occurs when sitting or during repeated movements in the work process, even without a high external load, is, in addition to high weights and large lever arms, another influencing factor which generates internal loads. The load is experienced not only by the intervertebral disc, but also by tensile structures such as dorsal ligaments. In particular, prolonged or frequently recurring flexion should therefore be avoided. This is one explanation for pain that also occurs in structures other than the intervertebral disc due to strain.

The training studies show - whether the back or the shoulders were trained - that the training success is strongly influenced by individual characteristics of the training participants. The example of training with the trunk muscle training device "Centaur" showed that only half of the participants were able to achieve a positive effect, the rest had no or even negative training success. Negative training success was characterized by individual comfort issues when using the training device. In situations like this, it is bad if you cannot offer alternatives.  Studies on another training device for the trunk muscles "Pegasus" and especially shoulder training show that different training contents and especially different training devices lead to almost the same training results.

Rehabilitative training should therefore be multifaceted. In addition to the individual and also training condition-dependent load capacity, the variability of the training plays a major role. In addition to changing the parameters for increasing load (volume, intensity, frequency), training content should also be varied, i.e. different exercises and equipment should be used in different sessions. Experience has shown that super training devices or sole universal remedies are only marketing ploys of sports equipment manufacturers, the effectiveness of their devices has often not been proven or probably cannot be proven.

Measurements of stresses at different workplaces show that different people process this stress differently, i.e. are subjected to different levels of strain, even if the strain is mechanically comparable. Experience, personal prerequisites and general fitness level play a decisive role in this respect. For example, it can be shown that young individuals with a high fitness level are less able to cope with an unfamiliar strain than older, less trained individuals who, however, have a greater wealth of experience and a more effective work technique in the activity in question.

As part of the measurements at the workplace, various measures to facilitate work (e.g. arm relief loops or upper body supports) were investigated. All measures or devices can be recommended, but individual fit must be ensured. It is also not advisable that relief devices or relief measures must be used according to fixed specifications. The highest acceptance and application rate was documented for voluntary offers according to individual time regimes.

Typical measures used to assess the severity of a job, such as weight to be manipulated, frequency of load manipulation, or forced postures, are not effective by themselves in describing characteristic features of specific jobs. Meanwhile, forced postures (e.g., frequently leaning forward of the trunk) are one of the most common causes of discomfort in the workplaces studied. The manipulation of heavy loads now only occurs fairly infrequently. Due to design constraints (sometimes higher category to protect life), work facilitation can sometimes only be achieved through organizational measures (e.g. job rotation).