Dear Marc Braker,
the special physical preparation for soccer players is a very interesting issue in which I was involved many times (the last, three years ago with the most prestigious Italian soccer team).
I can tell you that in general, as you wrote, the soccer players SST should foresee “strength training in the first stage of the preparatory period to ensure a deepening effect on the body, the second half exists of explosive efforts like jumping”, but this general indication is not enough because, in the preparation period, the training plan should include also the endurance training.
The strength component of soccer’s physical fitness model is similar to the model of 200 – 400 m Track&Field runners. So, the SSP model for soccer players should be similar to the “long sprint” runners and includes heavy weight squat, explosive effort squat jumps, jumps and bounces and sprint exercises.
The problem is that the soccer players preparation period is very short and they have no time to realise this model as the T&F runners. For this reason the high level soccer players usually don’t use the heavy weight strength training (squat) but only the explosive effort weight exercises (half squat jumps). Also, most of the soccer players that arrive in the “great” soccer clubs, never used before the heavy weight squat in their training, and they are not used to these exercises don’t want use them mainly because they don’t know how and how much these exercises could influence their condition.
For this reason many high level soccer players cannot resolve their physical preparedness problems during all their sport carrier.