how much is too much for soccer players?

Overtraining Syndrome Can Sabotage Performance

For athletes, the concept of overtraining might seem odd. You understand a high training load is needed to adapt and get better (known as “supercompensation”). However, too high of a training load with too little recovery is a poor way to achieve proper gains. Recovery is when the actual training adaptations occur, not during the training session. In fact, sometimes overtraining may not even be evidence of training too much, but recovering too little.