There is a large body of evidence demonstrating that high impact, dynamic physical activity (PA) performed during childhood and adolescence induces positive adaptations in bone and leads to the attenuation of a greater peak bone density in early adulthood. This has a protective effect against fracture and osteoporosis later in life. However, the exact patterns of PA (type, frequency, intensity and duration) that bring about these optimal adaptations remain unknown and so my research aims to establish these by developing a measurement technique that allows the impact of PA on bone health to be assessed in free-living situations.