Acute Serum Cartilage Biomarker Response after Walking and Drop Landing.

INTRODUCTION: An in-depth understanding of the healthy cartilage response to activities of daily living is needed to better understand the complex relationship between cartilage health and loading. The purpose was to assess the role of loading on the acute serum cartilage oligomeric matrix protein (COMP) response in recreationally active individuals.

METHODS: Forty individuals without previous lower extremity injury participated in this repeated-measures study in which each participant completed all conditions during independent data collection sessions separated by at least 1 wk. An antecubital blood draw was performed before and after walking, drop-landing, and control (i.e., sitting) conditions. Commercially available enzyme-linked immunosorbent assays measured COMP concentration. The acute COMP response was quantified as the percent change of COMP concentration from before to after each condition. A one-way, repeated-measures ANOVA compared the acute COMP response between conditions. Post hoc Pearson product-moment correlation and chi-square analysis determined the relationship between the walking and drop-landing acute COMP response within individuals.

RESULTS: Acute COMP response was greater after walking (+4.2, P = 0.008) and drop landing (+4.6%, P = 0.002) compared with control (-2.3%), but did not differ between the walking and drop-landing conditions (P = 0.596). The magnitudes of the acute COMP response during walking and drop landing were correlated (r = 0.56, P < 0.001). However, the direction (i.e., either increase or decrease) of COMP was not the same after the walking and drop-landing conditions (χ1 = 0.870, P = 0.351).

CONCLUSIONS: Walking and drop landing produced a greater acute COMP response when compared with a control condition in healthy individuals, but the acute COMP response was similar between the two physical activity conditions, although the conditions differed in magnitude and frequency of loading.