When I boxed I thought that was toughest. When I wrestled that was toughest. Chess is brutal. Catching an elbow in Bball is tough. Head butts in soccer hurt. Cross country nordic and track are a bitch. Be a fullback running into 300 pounders in football hurts like hell.
One toughest hardest break your back sport is Alpine Downhill ski Racing. No forgiveness. Unrelenting pain at over 90 MPH. One sport where no matter how great you train you are taxed more. When you leave that starting gate you are alone but you know fear and pain awaits you no matter how great you are.
Crash at 90 on sheer rock ice, racing again is secondary to the thought of breathing again. Sucking in oxygen at 11 thousand feet? Lungs hurt worse than legs and arms starving for air. Ice crystal form around a frostbitten nose and that only relents due to a fear of losing.
But what the heck that is just my view.