In 1973, Harriet Williams published in "Quest" on volunteer bias (self-selection bias) in kinesiology research. Williams' evidence-based commentary included a discussion on sex differences in volunteerism. More recently, some exercise and sports scientists (ESS) have suggested "investigator" bias explains the lower proportion of female than male participants in ESS research. Here, I explain volunteer bias warrants consideration in contemporary discussions on female participation in ESS research. I discuss sex differences in willingness to participate in certain research and how this corresponds to sex differences in personality traits and interests. I explain that sex differences in disease prevalence and physical activity participation also likely contribute to sex differences in ESS research participation. I conclude that, moving forward, evidence-based historical interpretations of female participation in ESS research are required, and future research should seek to establish a causal model of ESS research participation that considers both investigator and volunteer bias.