The document discusses physical preparation in professional football. It emphasizes the importance of aerobic capacity given that matches involve 72 minutes of intermittent high-intensity activity. The author advocates individualizing training loads based on physiological parameters and athlete sensations. Various testing methods are presented to assess the metabolic, muscular and recovery systems with a focus on aerobic thresholds, strength ratios, and heart rate variability. Training is aimed at developing the core, eccentric strength and flexibility while minimizing injuries related to fatigue.