82 male slaughterhouse workers participated in the study: 49 with chronic upper limb pain and 33 pain-free controls.
In the chronic pain group, maximum muscle strength and neuromuscular activity were reduced by 28% and 24–34%, respectively. The ability to rapidly exert force was reduced by 58–78 % as compared with the pain-free controls..
Pressure pain threshold testing of non-painful muscles in the leg showed evidence of hyperalgesia among the chronic pain participants. This may be due to central sensitisation processes.
The participants in the chronic pain group twere active on the labour market working fulltime, therefore they were not absent but working with reduced productivity.