Necessity of Considering Sex of Participants in Research: Observations Drawn From Resistance Training Studies of Older Adults.

Adult aging is a natural and complex phenomenon that is ostensibly alike between men and women. Generally, women live longer than men, yet women are frailer and have worse health at the end of life; the male–female health-survival paradox.What remains even more baffling than the potential paradox between longevity and function in men and women, is the paucity of research on sexand gender-specific differences to exercise, particularly in response to strength training which is known to benefit functional ability (Brady et al., 2014; Brandon et al., 2004; Papiol et al., 2016) and mitigate frailty (Watanabe et al., 2013). Although exercise and physical activity cannot independently alter the health piece of the paradox, notably that associated with disease, the female disadvantages in health and function have the potential to be quelled with strength training. Research published in the Journal of Aging and Physical Activity shows hope; yet, more studies are needed. Although the designation of male and female (biological study factors) and men and women (psychosocial study factors) is outlined for scientific research (see Sex and Gender Equity in Research Guidelines, National Institute of Health, and Canadian Institute of Health Research Resources), and evidence is accumulating across disciplines that various types of interventions (e.g., pharmaceuticals responses toward pain) have sex-specific (male and female) and gender-specific (men and women) outcomes, research and reporting on sexand gender-specific responses to exercise and physical activity is scarce. Publications, across the history (1993— Vol. 29, Issue 4, 2021) of Journal of Aging and Physical Activity were examined for strength training, gender (women and men), and sex (females and males) in older adults. The concentrated initial search of this journal through the PubMed database (https:// pubmed.ncbi.nlm.nih.gov/) identified few (<10) studies that examined sex/gender as an independent variable with resistance training. Resultingly, sex-related search terms were removed and papers that applied strength/resistance training interventions were evaluated for inclusion of both sexes/genders within the abstract, keywords, and title; and this resulted in 75 studies. Subsequent inspection of these primary papers prompted the exclusion of 44 studies because methodologically sex was not delineated as an independent variable (e.g., independent data not reported for males and females, participants statistically collapsed). This approach to research reporting, potentially arising from low statistical power or nonsignificant group differences need to discontinue. Current dogma is that to enhance reproducibility, advance knowledge of adult aging, and for this journal identify the benefit of exercise/physical activity, researchers should address and report relevant biological (sex) and sociological (gender) variables, beyond subject characteristics and statistical significance. Of the remaining 31 studies, 16 were eventually selected for inclusion based upon reporting sex-related differences in physical function and muscle strength (n = 7) and strength training interventions in older females and males (n = 9) (Table 1).