Thickness and Cross-Sectional Area of the Achilles Tendon in Marathon Runners: A Cross-Sectional Study

Abstract

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 mm2; 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. Level of evidence III; Retrospective study.

Lower-Limb Connective Tissue Morphologic Characteristics in Runners. How Do They Relate with Running Biomechanics and Tendon Pathology? A Systematic Review

“…Kenyan runners had a higher AT-CSA than their Japanese counterparts (41). AT-CSA showed a positive correlation with height (35,40), weight (40) and sex (i.e., males larger values) (40), while AT-Thickness correlates positively with height (35). Again, the repetitive loading over tendon appears as an influencing factor, since both running experience and kilometres run per week positively correlate with AT-CSA (40) and AT-Thickness (35,40).…”

“…Regarding sample characteristics, 16 studies were included. In relation with morphologic characteristics of the AT, 10 studies analysed the differences between runners and healthy untrained subjects (2,3,16,17,(31)(32)(33)(34)(35)(36). Regarding AT, Wiesinger et al (36) and Kongsgaard et al (37) studied the differences of the AT morphologic characteristics between runners and other sport athletes.…”

“…Differences in AT morphologic characteristics were also analysed in relation to other aspects: road runners and trail runners (38), running performance (39), leg dominant side (40) and nationality (Kenyan versus Japanese runners) (41). Finally, other subject characteristics such as sex, body mass, height, body mass index and running experience (35,40) were also studied in relation to the AT morphologic characteristics. The PT morphologic characteristics were analysed by four studies (2,17,36,39).…”

“…Other variables that positively correlate with the morphologic characteristics of the connective tissue are the ethnic, weight, height, sex and running performance. For the AT characteristics, a large majority of the studies showed that runners had greater AT-CSA and AT-thickness compared to untrained subjects (16,17,(31)(32)(33)(34)(35)(36). Although some studies did not found differences (2,3), in both studies, Kubo et al studied sprinters (2,3), while the rest of the studies assessed long distance-runners (16,17,(31)(32)(33)(34)(35)(36).…”

“…For the AT characteristics, a large majority of the studies showed that runners had greater AT-CSA and AT-thickness compared to untrained subjects (16,17,(31)(32)(33)(34)(35)(36). Although some studies did not found differences (2,3), in both studies, Kubo et al studied sprinters (2,3), while the rest of the studies assessed long distance-runners (16,17,(31)(32)(33)(34)(35)(36). It seems that running speciality might determine whether there exist differences, in terms of AT morphologic characteristics, between runners and untrained subjects.…”