"Osteoporosis is a common health problem associated with high morbidity, mortality and economic costs in older people, and prevention remains the most effective approach. Exercise is an evidence-based approach because of its impact on bone development, maintenance and strength but not all forms of exercise appear to strengthen bone. Further research is therefore needed to explore the role of short bouts of weight bearing exercise, that are acceptable to and feasible for adolescents, to supplement involvement in non-osteogenic activities. Plyometric jump training has been suggested as such exercise but the effects on adolescent bone health and associated metabolic processes have not been rigorously assessed.The aim of project PRO-BONE is to therefore longitudinally assess bone health and its metabolism in adolescents engaged in osteogenic (football) and non-osteogenic (cycling and swimming) sports and then examine the effect of a short and inexpensive plyometric jump training programme on these outcomes.Eighty-four male adolescents (12-14 yr) will be recruited as follows: footballers (n=24), cyclists (n=24), swimmers (n=24) and controls (n=12). Footballers, cyclists and swimmers will be randomly assigned in 2 subgroups (e.g.: intervention cyclists and control cyclists). Only intervention groups will perform the plyometric jump training [9 months, ~10 min/day, 3 to 4 times/ week (depending on progression)]. Body composition, fitness, nutrition, physical activity, anthropometry and serum bone turnover will be measured.The benefits are associated with PRO-BONE are: early detection of poor bone health, improved bone mineralization development during growth and contribution to Gracia-Marco’s development and integration at Exeter.Research will be hosted at the research-intensive University of Exeter (UK), in the Children’s Health and Exercise Research Centre (recognised for its international excellence), where Gracia-Marco is in a permanent full-time post as a Lecturer"