**1. Introduction**

Judo is a highly technical sport based on the principle of "maximum efficiency with minimum effort" [1]. A judo fight starts with the opponents both standing, attempting to throw each other off balance. After a throw, judokas transition to ground-fighting, the so-called "ne-waza" [2].

The fighting environment consists of constant changes of actions with applications of different movement structures [3]. The more athletes train and compete, the greater the range of powerful throwing techniques they are exposed to, and the chance of injury [4–8]. The frequency and number of injuries, as well as the severity of the injury, influences further training and competitions [9].

**Citation:** Błach, W.; Smolders, P.; Rydzik, Ł.; Bikos, G.; Maffulli, N.; Malliaropoulos, N.; Jagiełło, W.; Ma´ckała, K.; Ambrozy, T. Judo ˙ Injuries Frequency in Europe's Top-Level Competitions in the Period 2005–2020. *J. Clin. Med.* **2021**, *10*, 852. https://doi.org/10.3390/ jcm10040852

Academic Editor: David Rodríguez-Sanz

Received: 17 January 2021 Accepted: 16 February 2021 Published: 19 February 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

Recent studies analysing the frequency and type of injury in judo are available [10–15]. The rate of injury ranges between 12.3% and 30% [16,17]. Data on a large population (all ages and levels of performance) of French judokas during contests showed an injury incidence slightly above 1.1% [18].

The aim of the present investigation was to assess the frequency of injury in Europe's top-level judokas during high-level contests.

#### **2. Materials and Methods**

#### *2.1. Subjects*

Data were collected from a group of 26,862 high-performance judokas (15,571 men and 11,291 women) aged between 19 and 35 years in all judo weight categories competing in 128 international tournaments under the auspices of the European Judo Union (EJU), including European Judo Championships, in the period between 2005 and 2020. The participants were informed of the protocol and procedure of the EJU Injury registration form. Athletes signed the informed consent form. The EJU Injury registration form was approved by the Medical Commission of EJU. The study was approved by the Bioethics Committee at the Regional Medical Chamber (No. 287/KBL/OIL/2020).

#### *2.2. Study Design*

All relevant information was obtained using the questionnaire controlled and supervised by the European Judo Union (EJU) Medical Commissioner present at each competition. When judokas were injured, they were asked to complete this questionnaire and provide relevant information, with the help of the local medical staff and the EJU medical commissioner present. "Minor" injuries, such small nose bleeds or skin abrasions, which do not influence the athlete's performance in any way, were not counted. "Serious" injuries were defined as injuries so severe they needed transportation of the athlete to hospital. The Cronbach's alpha (=0.71, which is considered an acceptable value) was used to assess the validation of the EJU Injury registration form.

#### *2.3. Data Acquisition*

In the present study, an injury was defined as the physical condition which necessitated an intervention or medical advice by the medical team present at the judo tournament or a visit to the hospital. After each medical intervention, the injured athlete or the medical staff was asked to complete the medical form. The first part of the form asked the judokas to give general information, including their gender and weight category. In the second part, the medical staff was able to collect data on the anatomical location of the injury, type of injury, structure involved, side of the lesion, and whether the judoka was allowed to continue the fight. The diagnosis of the injury was always filled in on the medical form by the treating physician, either the team doctor or the physician of the local medical team. To ensure the privacy of the injured athlete, individual names were never mentioned. When the judoka had to be transferred to hospital, the injury was defined as "serious".
