This paper is about random coefficient trigonometric regression models and their use in gait analysis. Here gait analysis means free-speed walking on a level surface. Our study focuses on bootstrap-based prediction regions for the angular rotation curves of test children, when the relevant training data are gathered from normal children of comparable ages. Considerations that led to our choice of model and use of the bootstrap are given. Prediction regions and empirical bootstrap distributions are displayed, as is their application to several test cases. Also included is a study of the almost sure asymptotic behavior of the theoretical bootstrap probability of the prediction regions.