The influence of walking speed on the mechanoresponsiveness of biomarkers

The goal of this study was to examine short-term biomarker responses to walking at three different speeds in healthy individuals.

Healthy participants completed three study visits. At each visit, participants rested supine for 45 minutes, after which blood was collected. Next, participants completed a 30-minute treadmill walk, and another blood sample was collected. Finally, participants rested in a supine position for 45 minutes, after which a third blood sample was collected. At each visit, the treadmill speed was varied so that participants walked at a slow, moderate, or brisk speed. Serum biomarker levels were measured for cartilage oligomeric matrix protein (COMP), matrix metalloproteinase-3 (MMP-3), interleukin-6 (IL-6), and lubricin (PRG4).

Both COMP (p < 0.0001) and MMP-3 (p < 0.0005) showed significant increases in serum levels between pre- and post-activity measurements. The concentrations of both COMP (p < 0.0001) and MMP-3 (p = 0.04) decreased significantly from the post-activity to the recovery timepoint. Increasing walking speed elicited an increase in both serum COMP and MMP-3 concentrations (p < 0.05). On the other hand, we did not detect alterations in serum IL-6 or PRG4 concentrations due to walking or recovery.

Given the relationship we found between biomarker levels and walking speed, COMP and MMP-3 may be biomarkers reflective of the cartilage response to mechanical loading. Furthermore, these data suggest that mechanical loading through exercise may be a means to detect aberrant mechanical response. Finally, these findings serve as important baseline data for future studies investigating biomarker levels in those at risk for OA.