Abstract
Roughly 20% of Americans run annually, yet how this exercise influences knee cartilage health is poorly understood. To address this question, quantitative magnetic resonance imaging (MRI) can be used to infer the biochemical state of cartilage. Specifically, T1rho relaxation times are inversely related to the proteoglycan concentration in cartilage. In this study, T1rho MRI was performed on the dominant knee of eight asymptomatic, male runners before, immediately after, and 24 hours after running 3 and 10 miles. Overall, (mean ± SEM) patellar, tibial, and femoral cartilage T1rho relaxation times significantly decreased immediately after running 3 (65 ± 3 ms to 62 ± 3 ms; p = 0.04) and 10 (69 ± 4 ms to 62 ± 3 ms; p < 0.001) miles. No significant differences between pre-exercise and recovery T1rho values were observed for either distance (3 mile: p = 0.8; 10 mile: p = 0.08). Percent decreases in T1rho relaxation times were significantly larger following 10 mile runs as compared to 3 mile runs (11 ± 1% vs. 4 ± 1%; p = 0.02). This data suggests that alterations to the relative proteoglycan concentration of knee cartilage due to water flow are mitigated within 24 hours of running up to 10 miles. This information may inform safe exercise and recovery protocols in asymptomatic male runners by characterizing running-induced changes in knee cartilage composition.
Highlights
20% of Americans run annually, yet how this exercise influences knee cartilage health is poorly understood
We demonstrated that femoral, tibial, and patellar cartilage experience statistically significant percent decreases in T1rho relaxation times immediately following both 3 and 10 mile runs, with significantly larger changes occurring following 10 mile runs as compared to 3 mile runs
The results show that knee cartilage T1rho relaxation times were able to recover to within 2% of their baseline values within 24 hours of running up to 10 miles
Summary
20% of Americans run annually, yet how this exercise influences knee cartilage health is poorly understood. This data suggests that alterations to the relative proteoglycan concentration of knee cartilage due to water flow are mitigated within 24 hours of running up to 10 miles This information may inform safe exercise and recovery protocols in asymptomatic male runners by characterizing running-induced changes in knee cartilage composition. The present study builds upon the existing literature by investigating the dose effect and the recovery response to moderate running distances We hypothesized that both 3 and 10 mile runs would induce decreases in knee cartilage T1rho relaxation times, with larger changes occurring following the 10 mile run as compared to the 3 mile run. Due to fluid recovery into the cartilage, we hypothesized that the T1rho values measured 24 hours post-exercise would be significantly larger than those measured immediately post-exercise, approaching the baseline pre-exercise values
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