Preliminary synthetic MRI study on Achilles tendon dynamics in amateur marathoners

To observe alterations in the microstructure and chemical composition of the Achilles tendon (AT) in amateur marathon runners before and after a race using synthetic magnetic resonance imaging (SyMRI).

SyMRI examinations were performed on marathoners at three-time points: pre-race, 48 h post-race, and 2 months post-race. A control group also underwent SyMRI examinations. The AT was segmented into three regions: the muscle-tendon junction (MTJ), insertion (INS), and middle (MID) regions. T1 and proton density (PD) values were recorded in these regions. We compared T1 and PD values between the marathoners and controls at different time points.

The study included 15 marathoners (11 males, 4 females; mean age 41.6 ± 5.36 years) and 10 controls (7 males, 3 females; mean age 36.3 ± 8.77 years). T1 values in the INS region were significantly lower in marathoners than in controls (p < 0.05). At 48 h post-race, T1 values increased significantly in the INS region (12.1 % increase, p < 0.01), while PD values decreased across all three regions (12.1 %-21.3 % decrease, all p < 0.01). At 2 months post-race, T1 values in the INS region decreased compared to 48 h post-race (12.6 % decrease, p < 0.05), and PD values in the MTJ and INS regions increased (MTJ: 64.7 % increase, INS: 112.9 % increase, both p < 0.05). No significant differences in T1 and PD values were observed between 2 months post-race and pre-race.

Changes in T1 and PD values of the AT following a marathon are reversible. SyMRI quantitative parameters can indicate microscopic changes in the AT, with PD values being the more sensitive indicator.