These days, youth soccer seems to be synonymous with ACL injury. Recent studies have shown that ACL injury rates continue to rise even with the advent of cost-effective prevention programs such as the FIFA 11+. Experts in the field of physiology are well-aware of this and are trying to fix it, but what if one MAJOR cause of these injuries has nothing to do with the creation of 'better' injury prevention programs? What if simply educating coaches, parents, & players on the consequences of overtraining, and how to avoid it could make a massive difference in the frequency of ACL injuries?
Raymond Verheijen, of the World Football Academy, refers to something called the Accumluation of Fatigue which is a result of overtraining (amongst other things). Essentially this entails a slowing of the nervous system. While not exhaustive, the following are potential outcomes from accumulating fatigue:
Training at a slower tempo of play, slower actions, and more mistakes.
A slower firing of muscles which protect joints such as knees, ankles, etc. (essentially the message from the brain to muscles is slower).
This is especially scary for those with predisposed structural issues such as higher Q angles, or Valgus loading of the knees (both very common in females).
In a nutshell, the Accumulation of Fatigue stems from too many games and/or high load training sessions too close together, doing too much too soon in the preseason, playing at a higher tempo of play before being physically ready being to do so, high training loads too close together, etc.
That said, it is not uncommon for a youth soccer team in the US to participate in 2-a-days in preseason, enter a tournament and play 5 games in 3 days, play 1-2 league games on a weekend, and train 3-5 times per week, all the while participating in other sports at the same time. Oh, and they still go to school and are kids...
It's very realistic that a youth soccer player plays six games in one week (i.e. US Club Regional Championships) or sustain equivalent loads between training and games week-in and week-out throughout a given season.
Yet, the top youth academies in the world train 2-4 times a week, and play one game on the weekend. Why the disparity?!?!
1 Massive Reason: the thought that 'more is better' (probably stemming from Malcom Gladwell's misinterpreted '10,000 Hour Rule'). This simply isn't the case with a sport like soccer.
Training/playing more does not equate to training/playing better, in fact it's the opposite. Training/playing more forces players to play at a slower tempo in an attempt to avoid injury. In effect, the body goes into survival mode which prohibits skill acquisition and puts players at a higher risk for injury. Players need to be fresh to stretch their limits! Soccer is an intensity sport, where quality reigns supreme, not quantity.
Clubs SHOULD have people on staff that understand how to PROPERLY develop players. If they don't, find a club that does! If for some reason you don't have access to a club that does, introduce your local club to the World Football Academy (more info at: https://worldfootballacademy.com/).
Example of a recent study showing increases in youth ACL injury rates: https://www.ncbi.nlm.nih.gov/pubmed/28587262