Effects of long-term running on the structure and biochemical composition of knee cartilage in males: a cross-sectional study.

BACKGROUND: Running has been widely recognized as a beneficial activity for improving physical fitness, but it can also increase the risk of running-related injuries (RRIs). This study aims to assess the impact of long-term running on the structural and biochemical composition of the knee.

METHODS: This study recruited a total of 32 participants, including 16 male recreational runners, aged 28-49 years, with a running experience of 2-7 years, and 16 matched sedentary controls. Magnetic resonance (MR) scans of T2* mapping and three-dimensional double-echo steady-state (3D-DESS) were performed on all participants. The volumes, thickness, and T2* values of joint articular cartilage were obtained via automatic segmentation software.

RESULTS: Compared with the sedentary controls, runners exhibited significant increases in the volumes of both the femoral medial articular cartilage and the tibial medial articular cartilage. Additionally, there were significant increases in the thickness of several cartilage regions, including femoral medial cartilage, femoral medial articular cartilage, femoral medial thickness, femoral lateral cartilage, and tibial medial articular cartilage. Notably, the T2* values in the femoral lateral and tibial lateral cartilage of runners decreased significantly, while those in the patellar cartilage and medial tibial cartilage increased significantly. Runner pace was negatively correlated with the overall knee cartilage thickness (r=-0.556; P=0.02), femoral cartilage thickness (r=-0.533; P=0.03), and volume (r=-0.532; P=0.03) but positively correlated with the T2* value of the patellar cartilage (r=0.577; P=0.01).

CONCLUSIONS: Our study suggests that long-term mechanical stress from running may lead to increased thickness and volume in certain knee joint cartilage regions, possibly enhancing the functional adaptability of knee cartilage. The varying changes in T2* value in the tibial and fibular cartilage areas may indicate differing adaptability to pressure.