Examination of participant sex bias in international society of biomechanics conference abstract submissions: patterns across cohorts, countries, and contexts

Sex bias in cohorts occurs when one sex is overrepresented. This study evaluated sex bias in study participant cohorts among abstracts accepted for the International Society of Biomechanics (ISB) Congress in 2025. Analyses focused on participant inclusion and abstract characteristics by lead author affiliated country, research topic, and cohort type (human/animal/computational). Using NotebookLM Gemini 1.5 Pro and a predefined prompt, data were extracted and analysed from 1,394 accepted abstracts. Of the 1202 abstracts with study participants, 43% did not report sex distribution, 13% had very small samples sizes (<6 participants), 18% had an unbalanced cohort (<30% representation of one sex), and only 26% had a balanced cohort. Among unbalanced abstracts, 64% showed an overrepresentation of male participants, for which a scientific justification was provided in only 1% of cases; in female‑biased abstracts, justification was provided in 18% of cases. Variation in sex representation and reporting was observed across countries, topics, and cohort types, with applied domains such as Military and Sport biomechanics and Animal studies demonstrating lower levels of balance or transparency. Taken together, these findings indicate that sex distribution is frequently insufficiently reported or unevenly represented at the conference abstract stage, but these may be subsequently modified if the study is still in process