Where are the female participants in resistance training and muscle hypertrophy research? A review of gender/sex representation

This systematic review aimed to evaluate the representation of female participants in resistance training (RT) studies investigating hypertrophy and to assess associations between participant sex, methodological features, authorship, and temporal trends. This review included RT studies published in peer-reviewed journals that assessed hypertrophy outcomes in young adults. Reviewers independently screened studies and extracted data on participant sex, menstrual cycle phase reporting/consideration, use of molecular or biopsy analyses, and gender/sex of first and last authors. A total of 570 studies were included. Of these, 72.2% recruited male participants, 11.0% female participants, and 16.8% included both sexes. Among studies including female participants, 8.5% reported or accounted for menstrual cycle phase, while 87.3% did not mention it. Molecular analyses were nearly four times more frequent in studies with only male participants (23.6%) than those including female participants (6.5%; χ²=9.45; p<0.009). No association was found between participant sex and use of muscle biopsies or author gender/sex. A 10-fold increase in RT publications occurred in the 21st vs. 20th century, yet the sex gap persisted. Studies published in 2020-June 2023 showed modest improvement versus 2001-2019, with fewer male-only and more female-only and mixed-sex samples (χ²=16.43; p=0.00027; Cramér's V=0.18). Despite growing evidence that females and males exhibit broadly similar relative hypertrophy and molecular responses to RT, substantial sex bias persists in hypertrophy research. Although studies published since 2020 show modest improvement in sex-inclusive recruitment, male-only designs still predominate, and limited menstrual cycle phase reporting/accounting continues to constrain transparency and generalizability.