What are the causes of sports injuries?

What are the causes of sports injuries ?

(i) Lack of physical fitness of player.
(ii) Lack of psychological readiness.
(iii) Over training or over strain of muscle.
(iv) No utilisation of protective guards.
(v) Faulty skills actions.
(vi) Not adopting rules and regulations.
(vii) Non-qualified teacher/coach or his absence.
(viii) Poor maintenance of playfield.
(ix) Lack of rest and recovery.
(x) Lack of proper warming-up.