You'll never look at a tennis player's racket arm the same way again 🎾 As a professional tennis player trains year after year, their skeleton adapts to the repeated impact of every shot. This causes the bones in their racket arm to become up to 20% thicker and stronger than the other and reduces the risk of breaking. Watch the full clip and other videos from Secrets of the Human Body via the link in bio 🔗 #Tennis #Wimbeldon #RacketSport