THICKNESS AND CROSS-SECTIONAL AREA OF THE ACHILLES TENDON IN MARATHON RUNNERS: A CROSS-SECTIONAL STUDY

Introduction: This study aimed to measure thickness and cross-sectional area of the Achilles tendon (AT), and the range of motion of the ankle joint in dorsiflexion of amateur marathon runners compared to non-active people. Objectives: To analyze the relationship between cross-sectional area and thickness of the Achilles tendon in marathon runners and age, anthropometric characteristics (height and body mass), training habits, running experience, marathon performance, and range of motion in the ankle joint. Methods: Achilles tendon thickness and cross-sectional area were measured using ultrasound images of the left leg in 97 male amateur marathon runners (age 42.0 +/- 9.6 years; height 175 +/- 6 cm; and body mass 73.7 +/- 8.6 kg), and 47 controls (39.9 +/- 11.6 years; 176 +/- 7 cm; 79.6 +/- 16.1 kg). Results: Achilles tendon thickness (4.81 +/- 0.77 vs. 4.60 +/- 0.66 mm; p = 0.01) and cross-sectional area (60.41 +/- 14.36 vs. 53.62 +/- 9.90 mm(2); p < 0.01) were greater in the marathon runners than in non-active people. Achilles tendon thickness has been correlated, in a weak but significant manner, with years of running experience. Moreover, marathon runners showed increased ankle range of motion (81.81 +/- 6.93 vs. 77.86 +/- 7.27 grades; p<0.01). Conclusion: Male amateur marathon runners have hypertrophy of the Achilles tendon compared to non-active people, and this enlargement is mediated by running experience. In addition, range of motion in ankle dorsiflexion is favored by marathon training.