this investigation, a total of 134,570 amateur soccer players
were studied, all of whom registered with the Spanish
Football Federation and played in domestic (national or
regional) leagues. The study population included only
male soccer players aged from 18 to 55 years. From the
total number of participants in this investigation, 86.0%
(n = 115,703) were soccer players aged 30 years, and
the remaining 14% (n = 18,867) were soccer players aged
30 years. Professional players were excluded from the
sample. Injuries were documented for every player, and
exposure time was calculated by assigning 1 match (90
minutes of play) per week for 38 weeks (to comply with regular
soccer competitions) and 2 training sessions (60
minutes of play each) per week for 48 weeks to each registered
player. The study was revised by a research ethics
committee in accordance with the latest version of the Declaration
of Helsinki. The research ethics committee indicated
that this investigation did not require approval.