They are being taught by in-experienced coaches who are unaware of the complexities involved in dealing with the sport.
Collisons with others
Maturity and technical ability.
Osteomyelitis (blood-borne infections resulting from bone disease).
Lethargy, burnout or exhaustion.
Changes in technique.
Drop in performance.
Illness and injury
Psychological, physical and physiological preparation.
Removal of waste products and the importing of new nutrients.
Reduce the likelihood of sprains, strains and other injuries.
Instructions and demonstrations must be clear, concise and precise.