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factors. However, there are many cases in job (re)design where the engineering control approach
cannot eliminate all of the hazards account for LBD. Therefore, administrative control approaches
are used as a secondary option or in parallel to organize the structure of the labour, and also,
to inform the workers how to seek for a correct work technique for protecting their backs from
injury. Workers who manipulate handling devices (cobots) also seek information about the correct
use of the devices, especially in the presence of accelerations (Chaffin, Andersson, and Martin,
2006; Lavender, 2006; Op de Beek and Hermans, 2000). All these collaborative robotic systems
extent workers’ physical capability. However, these devices need to take into account worker’s
biomechanics and motor control in order to be used effectively. Description of the biomechanics
alone cannot explain whether the natural limits of worker’s motor and sense system capabilities
are being reached during the manipulation.
1.6.2.
Manual Material Lifting and Lowering Work-Technique
The training of workers to recognize, evaluate and manage occupational risk factors is incorporated
into the prevention strategy of the EU-OSHA (Op de Beek and Hermans, 2000) and NIOSH (Cohen
et al., 1997) as a proactive action to cope with WRMSD. On the other hand, the European
Guidelines for Prevention in LBP does not recommend information, advice or instruction on
biomechanics or lifting techniques for prevention in LBP, but it rather recommends secondary
intervention, like the prevention of recurrence and of the disability from LBP (Burton, 2005) that
seems to be more realistic and feasible than primary intervention (Balagué et al., 2012; Snook,
2004).
The technique of lifting and lowering objects at work is determined by assessing worker neuromusculoskeletal performance limits, as well as the constraints imposed by the physical demands
of the workplace, which include the handled load and the specificity of the work task, under the
framework that any mismatch leads to WRLBD (Bloswick and Hinckley, 2004; Chaffin, Andersson,
and Martin, 2006; Jones and Kumar, 2004). The ISO 11228-1 (2003) standard, makes reference
to the association of the manual-handling injuries with the (I) individual physical capabilities of
the workers, like the decreased lifting strength in women, the (II) less skilled actions in young
workers, and (III) the age-related alterations of the viscoelastic properties of the biological tissues.
However, the aforementioned imposed constraints cannot define unambiguously which motor
patterns the workers can execute during lifting and lowering tasks.
Motor redundancy at the kinematic level, which is arose by the numerous DOF of the human
locomotor apparatus compared with the substantially lower anatomical constraints that are imposed
by the structure of the musculoskeletal system at joints’ level, gives to the workers the possibility
to adopt an infinite number of postures during lifting or lowering tasks, and consequently the
ability to execute a countless voluntary motor patterns in order to accomplish their labor activities.
This phenomenon, of the accomplishment of the same task using different body configurations
and environmental means is referred to as “motor equivalence” (Berkinblit, Feldman, and Fukson,
1986; Bernstein, 1967; Hebb, 2002; Lashley, 1930; Tunik et al., 2003). Besides that, it seems
coherent that similar muscle activation patterns cannot be presented always among workers or
in the same worker who performs replications of the same lifting or lowering task in terms of
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