The more you interfere with the function of your body, that Nature provided you at birth, the more injuries and pain you will have as well as the worse you will perform. Below are 4 areas I see footballers sabotaging their short-term & long-term performance:
How & WHY
The brain will adapt to whatever stimulus you give it. When you break a bone, and they put it in a cast to heal, all the muscle falls away. Why is that? With no movement or use, the brain thinks you don't need it anymore and recycles it. This is what happens when you use heavy weights to perform slow, repetitive movements that do not occur in any sport. The brain remembers that the same way it adapts to your feet being stuffed into a narrow cushioned shoe. It adapts to survive even at the expense of health & performance.