High-school girls and collegiate women have tremendous opportunities to participate in athletic teams. Young girls are also playing in club and select teams at an early age and often, year-round. There are many benefits for participating in sport and physical activity on both the physical and mental health of girls and women. Decreased risk for heart disease and diabetes mellitus, along with improved self-esteem and body-image, were among the first reported benefits of regular physical activity. In addition, sport participation and physical activity is also associated with bone health. Athletes have a greater bone mineral density compared with non-active and physically active females. The increase in bone mass should reduce the risk of fragility fractures in later life. There appears to be a window of opportunity during the development of peak bone mass in which the bone is especially responsive to weight-bearing physical activity. Impact loading sports such as gymnastics, rugby or volleyball tend to produce a better overall osteogenic response than sports without impact loading such as cycling, rowing and swimming. Relatively little is known about the impact of retiring from athletics on bone density. It appears that former athletes continue to have a higher bone density than non-athletes; however, the rate of bone loss appears to be similar in the femoral neck. The positive impact of sports participation on bone mass can be tempered by nutritional and hormonal status. It is not known whether female athletes need additional calcium compared with the general female population. Due to the increased energy expenditure of exercise and/or the pressure to obtain an optimal training bodyweight, some female athletes may develop low energy availability or an eating disorder and subsequently amenorrhoea and a loss of bone mineral density. The three inter-related clinical disorders are referred to as the 'female athlete triad'. This article presents a review of the relationship between sports training and bone health, specifically bone mineral density, in young athletic women.

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Reproductive cycles are described for subtidal and intertidal populations of the, starfishAsterias rubensL. and for a subtidal population of the starfishMarthasterias glacialisL. on the south-west coast of Britain. IntertidalA. rubenshad a clearly defined reproductive cycle with spring-early summer spawning. Pyloric caecum indices were inversely related to gonad indices. SubtidalA. rubenshad lower gonad indices and less seasonal variation in the pyloric caecum indices. Gonad indices ofM. glacialissuggest few animals in the population studied were breeding, but it is likely that this species also spawns in summer.Plankton samples and larval rearing studies suggest a planktotrophic pelagic life of approximately 90 days forA. rubens. Field observations and laboratory experiments show larvae settle on a wide range of substrata. Recruitment to an intertidal population ofA. rubensat Hollicombe Reef occurred in July 1980 and September 1981. Growth of juvenile starfish was followed for 17 months. Juvenile starfish feed carnivorously at the completion of metamorphosis. Early growth is rapid; however, there is a reduction in the growth rate during winter months. Feeding and growth of juvenileA. rubensis compared with published data on juvenile starfish of other species.

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