Acute changes of achilles tendon thickness investigated by ultrasonography after shotokan and kyokushin karate training

Background and Study Aim: Ultrasonography proved to be a useful tool to investigate the morphology of the Achilles tendon. Studies exist assessing the role of exercise on Achilles tendon morphology after vertical jump and treadmill running, and Achilles tendon dimensions noticeably decreased following heavy resistance exercise. However, little is known regarding the influence of different karate disciplines as shotokan and kyokushin on Achilles tendon thickness. Thus, this study aimed to establish whether the acute changes of Achilles tendon are a phenomenon characteristic of different styles of karate training. Material and methods: Twenty-four male partcipants (12 shotokan and 12 kyokushin karate athletes) underwent sonographic examination with Honda HS – 2200 (Honda, Japan) ultrasound scanner. The Achilles tendon of both legs was measured twice before and then immediately following training. The sagittal thickness of the tendon was observed at a point exactly 10 millimetres proximal to the calcaneal insertion. Results: In shotokan karate athletes, Achilles tendon thickness decreased significantly from before (7.9 ±1.0 mm) to after the training session (5.4 ±0.2 mm). In kyokushin karate athletes, the thickness of Achilles tendon did not change significantly. Before training it was (5.6 ±0.7 mm), after training was (5.6 ±0.7 mm). Significant differences were also found between shotokan and kyokushin karate athletes (p = 0.001). Conclusions: Achilles tendon thickness decreases immediately after specific training in shotokan karate, but there are no observable changes in kyokushin karate group. In order to establish a concrete diagnosis for preventative and rehabilitative techniques, it is necessary to expand on the current research to observe the long-term effect of training on Achilles tendon thickness and morphology.