Cryotherapy chambers and other practices have little evidence behind them, says top performance director Dr Claire-Marie Roberts was working at Coventry City when she received a call from someone asking whether she knew how much oxygen was in the atmosphere. As the performance director, responsible for optimising players’ potential, she was accustomed to being pitched the latest gimmick promising miraculous gains. At times, she could receive up to 50 LinkedIn messages a week offering a device,…