A model is presented for the determination of aerodynamic drag forces on runners. The model consists of a series of conjugated circular cylinders, to stimulate the trunk and appendages, and a sphere to stimulate the head. Results are presented for three runners representing respectively, adult American males in the 2.5, 50 and 97.5 percentiles of the population. It is found that power dissipated in overcoming air resistance for these three runners ranges from 0.33 to 0.49 horsepower at a sprint speed comparable to the current world's record for one hundred yards. In addition an alternate model, consisting of a single circular cylinder, is presented that simplifies the determination of total aerodynamics drag. The accuracy of this model is determined by comparing results for total drag with those found with the more complex model. It is found that the error ranges from 5 to 8.9 percent.