The aim of this article is to extend the standard neoclassical consumer theory to explain the allocation of individual time to physical activity and sports. The authors assume a Constant Elasticity of Substitution (CES) utility function and they estimate the model using the Seemingly Unrelated Regression (SUR) method and the Heckman two-step procedure. They run separate estimates for men and women using the Spanish Time-Use Survey conducted in 2002-2003. The results show that there are gender differences in the determinants of the allocation of time to physical activity. Moreover, participation in physical activity and sports and the time devoted to these activities seem to be based on different decisions.