Modelling effects of drug testing procedures on performance trends in the shot put

Objectives: The effect of performance enhancing drugs on historic performance records in sport is open to interpretation and needs empirical support. Here we addressed this contentious issue by assessing whether a double sigmoidal model could detect decrements in sporting performance attributed to introduction of drug testing protocols.

Methods: Distances thrown by the top 25 male and female shot putters since the end of the 19th century were modelled using a double sigmoid.

Results: First-phase peak acceleration in the men’s and women’s shot put was reached in 1981 and 1986 respectively coinciding with advent of systematic doping programs. Shot put performance of men and women underwent a second-phase decline of 5.3 m and 8.9 m, in 1991 and 1994, respectively. Performance decrements in women’s shot put were nearly double that for men, but much of this difference resulted from the reduced mass of their shot. Controlling for changes in mass, women’s shot put performance appears to decline to a greater extent than men’s, based on raw energy calculations.

Conclusions: The double sigmoidal model detected a second-phase decline in shot put performances. We attribute this data feature to onset of improved drug testing protocols and a consequential reduction of doping. The assumption is that drug testing programs of shot putters has been successful and reduced the prevalence of drug taking in that sport. The application of a double sigmoidal model to historic performance statistics can be used to detect unknown interventions in analyses of sports performance.