Health is becoming an increasingly important aspect of built environment design. We aim to bridge the gap between existing knowledge in medicine and its potential applications. This paper tests the extent to which Active Urbanism can facilitate gaining and maintaining bone mass widely across the population through encouraging serendipitous high impact exercise. Based on a review of successful high impact exercise programs, we run a biokinetics experiment in a laboratory measuring ground reaction forces to match those based on field sociological pilot studies in the urban environment. Considering data collected, Active Urbanism can increase the bone density of an average child not previously involved in sport by 12% in 10 years, and that of an average adult by 2.8% in 10 years. This new parameter has the potential to support infrastructure and landscape designers to optimize their plans and will need further examination by communities of these practices.