Prevention of MSDs by workload optimization based on external and internal load assessment methods Danuta Roman-Liu Central Institute for Labour Protection – National Research Institute

Work incapacity due to MSDs in

Work incapacity due to MSDs in relation to all incapacities in 2003 – 2005

Sectors with the highest rate of MSDs ( according to Polish National Labour Inspectorate ) transportation agriculture, fishing, forestry mining building industry, wholesale and retail trade hotels and restaurants, health care

Risk factors for MSDs Home environment ٭Leisure time ٭Diet ٭Sport Work environment ٭ Biomechanical factors posture force time sequences ٭ Psychosocial factors job demands control social support Individual characteristics ٭Genetically determined inclination to diseases ٭Personality ٭Gender ٭Age ٭Physical capacity

External and internal load at the work stand Internal load is the reaction of musculoskeletal system to the external load. Methods:  sEMG  ECG  HR  Oxygen consumption  Subjective assessment External load can be assessed as a function of parameters describing performed task (body parts configuration, exerted force, time). Methods:  NIOSH  OCRA  OWAS  LIMB

Assessment of muscle load and fatigue using sEMG Placement of sEMG electrodes sEMG registered from four upper limb muscles

Ovako Working Posture Analysis System

Packing stand involving repetitive tasks Before intervention After intervention intervention

Musculoskeletal load assessment on the Bale Opener work stand Tasks (phases in the cycle)Time of phase (s) Preparation45 Cutting ties60 Removal of ties45 Walking to the other side of bale24 Cutting ties30 Removal of the ties280 Disposal of ties20 Walking to the lift30 Steering the lift120 Workers at the „Bale Opener” work stand reported pain in wrist and hand. Musculoskeletal load of upper limb was assessed by means of sEMG.

Load level of examined muscles during each of cycle phases [% MVC] [% of cycle time] RMG [% MVC] [% of cycle time] ECR [% MVC] [% of cycle time] FCU

Results Analysis of musculoskeletal load of forearm and hand shows that: ٭high musculoskeletal load of hand ٭lower, however still high, musculoskeletal load of forearm ٭the highest musculoskeletal load during tasks of cutting ties and this can cause upper limb pain ٭an important factor in the development of pain symptoms can be the shape of steering device, which is the main cause of musculoskeletal load in phases of steering the lift ♦ Changes of the shape of steering device by having it smaller and lighter with shape fitting the hand and decreasing the push button force. ♦ Reduction of musculoskeletal load during cutting ties can be reached by implementation of scissors with pneumatic, hydraulic or electric aid. Indicators for ergonomic intervention