David Hartley completed his BSc (Hons) Sports Rehabilitation and MSc Strength & Conditioning at the University of Salford. He has worked in high-level football for over 12 years, including spells in the English Premier League, English Championship and the Scottish Premiership, at both academy and First Team level. He has a special interest in growth & maturation and his MSc research project investigated the relationship between biological age and physical performance of youth athletes. He is currently Head of Academy Sports Science & Medicine at Celtic Football Club and oversees the athletic development, monitoring and medical provision of players aged 10-18 years old.