Can intense athletic training cause progression of a thoracic hyperkyphosis in the immature athlete? The lack of prospective, controlled trials addressing this issue precludes a definitive answer. Hyperkyphosis is defined radiographically as a thoracic kyphosis exceeding 55 masculine in 10- to 20-year-olds, and 65 masculine using back surface measurements. In this paper we review the biomechanical scenarios that could lead to an increase in kyphosis in the immature athlete via excessive mechanical loading. These include fall-related impacts, rapid acceleration/deceleration of heavy weights, and maximum effort trunk extensor muscle lengthening contractions. Research is needed on whether the number and magnitude of vertebral loading cycles, the recovery interval between loading cycles, and the frequency of training affect apophyseal growth during periods of rapid growth of the apical vertebrae in a hyperkyphotic spine.