Horse racing is a weight category sport and jockeys must chronically maintain a low body mass, necessary to attain the stipulated competition riding weights, whilst maintaining a sufficient level of physical conditioning in order to compete, possibly on a daily basis, in several races each day, over the protracted racing season. The purpose of this study was to further investigate the acute and chronic effects of the common weight loss practices used to rapidly reduce body mass in preparation for racing, building on the existing knowledge and subsequently attempting to improve the health, well-being and overall performance of jockeys throughout their racing career and beyond. Methods: The primary aim was achieved through the completion of 3 independent, though related studies. Study One: The effects of acute body mass loss in preparation for racing on cognitive function, balance and anaerobic performance were assessed in a group of jockeys in a simulated and competitive racing environment. Study Two: The potential long term health impact associated with the prolonged use of rapid weight loss strategies and an energy restricted lifestyle was established in a group of retired jockeys. Study Three: The physiological demands and energy requirements of training, racing and other daily activities were determined. Results: Study one showed that rapid reductions in body mass resulted in no significant impairments in cognitive function, balance or anaerobic performance however large individual variability in responses were apparent which is worrying in terms of the safety and welfare of all surrounding jockeys on the track. Study two suggests a life of chronic weight restriction and reliance on unhealthy weight making practices may have some long term health effects particularly in relation to gain in body mass since retirement, reduced resting metabolic rate and bone health. Study three suggests competitive horse racing requires both aerobic and anaerobic fitness and it further reports that the total estimated energy expenditure on a non-racing day is higher than that on a racing day and as a result the deleterious effects of living in a state of low energy availability may be further exacerbated. Conclusion: Results from this study suggest horse racing is a physically demanding sport and that making weight may result in many individual adverse responses both acutely and chronically. Ideally jockeys should be tracked longitudinally with information and support systems readily available to jockeys to encourage the adoption of healthier making weight strategies, assisting jockeys in enhancing their health, wellbeing and overall performance throughout their sporting career, and beyond.