Large sex difference despite equal opportunity: authorship of over 3000 letters in exercise science and physical therapy journals over 56 years

Letters to editors of journals are a hallmark of scientific debate and communication. Incidentally, letters also serve as a relatively unconfounded model to test for a potential sex difference in scientific engagement because opportunity to write letters is equal. When studied in exercise science and physical therapy journals, the model is strengthened because these fields have higher numbers of female degree earners. The purpose of the current study was to determine if, despite equal opportunity, there is a sex difference in authorship of letters written to scientific journals. An inventory of letters written to 27 exercise science and physical therapy journals from 1963 to 2018 was created. Sex of the sole or first author was determined by first name or internet searches for the author’s photograph or biography. The search discovered 3203 letters. Author sex was determined for 3021 letters. Males authored 86% of letters; females authored 14%. Males authored more letters than females in all 27 journals and in every year except 1964. Thirty males authored five or more letters over the 56-years period. Only two females authored five or more letters. Exploratory analyses with Chi-square tests revealed the author’s sex was not associated with the editor’s sex. The results suggest males might “lean in” more than females to discuss and critique science publicly. This sex difference in letter writing might be due to psychological differences between the sexes—males are generally less agreeable, more competitive, and higher risk takers than females. However, such hypotheses remain to be tested.