Responsiveness of selected biomarkers of tissue damage to external load and frequency during repetitive lumbar flexion/extension

• Biomarkers of tissue damage may aid in assessing occupational injury risk.
• Participants performed lumbar flexion/extension with varied load and frequency.
• Interleukin-6 was sensitive to the level of external load.
• Creatine Kinase was sensitive to the level of external load and task frequency.
• Such dose–response relationships support potential occupational use of biomarkers.

Quantifying biomarkers related to tissues commonly injured in occupational settings may be useful for exposure assessment or predicting injury risk. Here, serum levels of Cartilage Oligomeric Matrix Protein (COMP), Interleukin-6 (IL6), and Creatine Kinase (CK) were obtained before and after participants completed a repetitive lumbar flexion/extension task. The task was done for one hour, using five combinations of external load and frequency. COMP levels did not change over time or between exposure conditions. IL6 levels were significantly affected by time and by external load, while CK levels were significantly affected by the load × frequency interaction. Greater external load and frequency (for CK only) resulted in greater peak values of IL6 and CK, and both biomarkers recovered by 24 h after task completion. Since IL6 and CK levels exhibited a dose–response relationship to exposure levels, they may have potential use in the occupational domain.Relevance to industryThis study investigated the effects of external load and frequency, during repetitive lumbar flexion/extension, on biomarkers that reflect tissue injury. Responses of biomarkers related to muscle use and damage (IL6 and CK) support earlier epidemiological evidence, and these may have future value in predicting occupational injury risk.