Children are bad for your health

I do a lot of sports and am mercifully free of injury. Even the more stupid activities late in my pregnancy (Macau running race, rowing, paddling) left me without even the smallest twinge. At the weekend I pulled a muscle in my shoulder and now I can't move my left arm very much. I didn't do it rowing or paddling. It was during a water fight in the sea with a friend's six year old son, throwing him into the waves after he had splashed me. I had no idea playing with children could be so dangerous!