Swimming training is associated with decreased bone mass and lower bone mass acquisition during growth periods, mainly when compared to other weight-bearing sports. Little information is available in adolescents pointing in the same direction but still controversial.

On the other hand, bone strength do not only depends on bone mass but on bone structure and microarchitecture. The cross sectional area, cortex thickness or trabecular density are important aspects of bone health. There are few studies on the effect of swimming on bone architecture of adolescents. This information is relevant for present and future health of adolescents practicing swimming and for all the organizations promoting this sport. Jumping and whole body vibration training programs seem to elicit important osteogenic effects; however, there is little information on this regard in adolescent population, even less in these adolescents with potentially decreased bone acquisition such as swimmers.

The main aims of this research project are therefore, to analyze the effect of swimming training on bone mass, metabolism, structure and architecture in adolescents analyzing possible relationships among them. Secondly, to test whether including short boots of jumping or whole body vibration may be able to palliate the possible deleterious effects of swimming and facilitate a normal or even healthier bone development. And finally to study the durability of training-related bone gains over time.

Inclusion Criteria:

• Specific for the swimmers: With a history of training at least 3 years for more than 6 hours per week and currently still training
• Specific for the control group: Subjects that do not perform more than 3 hours of physical activity per week

Exclusion Criteria:

• Non-caucasian
• Smoking
• Taking medication affecting bone