2.1. Participants

A sample of 52 male athletes between 14 and 17 years of age were selected from a semiprofessional football club. Inclusion criteria were as follows: (a) dominant right lower leg (i.e., the right leg is preferable during kicking); (b) minimum score for each of the questions from the Oslo Sports Trauma Research Centre questionnaire (OSTRC) [16], regarding injury, illness, or other health problems during the past week prior to the study; and (c) no injuries that prevented training or competition participation for longer than one week, within a period of four months prior to the examination. Full characteristics of the participants are presented in Table 1. All participants and their parents or legal guardians received oral and written information about all procedures and gave their signed informed consent to participate. The study was designed according to the Declaration of Helsinki and was approved by the local ethical committee.

Basic data of participants—mean and standard deviation (SD).

^aFor how many years soccer has been practice prior to the study? ^bWhich leg do you prefer when playing football? ^c % number of participant's declaration; OSTRC: Oslo Sports Trauma Research Centre questionnaire; BMI: body mass index.