Renowned football trainer Raymond Verheijen has blasted Manchester United manager David Moyes and has labelled his coaching methods as prehistoric.
The issue cropped up after Dutch international striker Robin van Persie injured himself in a pre-season game in Japan Tuesday.
Van Persie, who was the top scorer for United last season, was taken off at half-time after experiencing a tightness in his thigh.
"In Sydney Moyes said: 'We've overtrained Robin this week to build up his fitness'. (In Japan) he picked up muscle injury. It really makes you wonder how these prehistoric training methods can still take place at the highest level," Verheijen, who has worked with Barcelona, Chelsea and Manchester City, wrote on his Twitter account.
"The only way to solve this problem in Jurassic Park is to improve education of these dinosaur coaches, fitness clowns & scientific cowboys," Verheijen further said.
He criticised coaches who still relied on the old-age methods and said that most of them were in "denial".
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"All over the world in pre-season you see the pattern 'overtraining-fatigue-injuries'. Always avoid accumulation of fatigue in pre-season," he tweeted.
"But as long as most dinosaurs are still in denial & ignore how things develop in other countries, nothing will ever change in Jurassic Park. Obviously, players like RVP should learn to protect themselves better against 'overtraining' & 'punishing training'."