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Is There a Bias Against Women in Exercise Research?
The purported bias against women in exercise research may instead reflect bias against acknowledging sex differences.
About the Authors, PhD, is an Adjunct Senior Lecturer in the School of Medical and Health Sciences at Edith Cowan University. He is the author of over 70 peer-reviewed research articles and founder of The Nuzzo Letter on Substack. He is active on Twitter @JamesLNuzzo.
Robert O. Deaner, PhD, is a Professor in the Department of Psychology at Grand Valley State University. His research uses an evolutionary perspective to illuminate sex differences in motivation.
In 2014, Costello and colleagues published an influential paper in the field of exercise science titled, “Where are all the female participants in sports and exercise medicine research?” The authors embarked on a comprehensive tally of male and female participants involved in studies published in three leading sports medicine journals between 2011 and 2013. They found that 61 percent of the participants were men and 39 percent were women.
The study further revealed that a majority of research included mixed-sex samples and that male-only studies were more common than female-only studies. The authors acknowledged that “a range of physiological and methodological issues” might contribute to the differential male-to-female ratio in sports and exercise medicine research. Nevertheless, their paper was framed primarily from a perspective of bias or discrimination against women in sports. The impact of this paper has only grown over time; in the seven years following its publication, it has garnered more than 400 citations, including several commentaries endorsing the perspective of widespread bias against women in exercise and sports science.
The common expectation that the distribution of male and female research participants should invariably reflect a 50/50 ratio, and that any deviation in representation must be attributed to investigator bias, is logically flawed. A variety of factors, aside from investigator bias, may contribute to a greater representation of men—or women—in such research. For instance, both the interest and willingness of individuals to participate in research may be significant factors.
The link between sex and willingness to participate in research is not a new concept; it was first noted in the field of experimental psychology several decades ago. In a notable example from 1960, Howe discovered that women were less willing than their male counterparts to participate in an experiment involving electric shocks. By 1975, this notion had gained such traction that Rosenthal and Rosnow devoted 13 pages in their book, The Volunteer Subject, summarizing the evidence supporting an association between sex and the willingness to participate in research.
Despite this established knowledge, there has been a conspicuous absence of any inquiries directed at men and women regarding their interest and willingness to participate specifically in the domain of exercise and sports science research.
Our New Study
In response to this deficiency, we recently undertook a survey-based study to determine whether sex differences in interest and willingness to participate in exercise research exist. Moreover, we sought to discern whether these differences might contribute to the unequal representation of men and women in this area of research. Our survey targeted two distinct groups of participants. One group consisted of 129 men and 227 women who responded to study advertisements on social media and survey-sharing websites. The other group comprised 155 men and 504 women who were undergraduate students in the Psychology Department at Grand Valley State University (Michigan, U.S.). The responses from the two groups revealed an array of sex differences.
When asked about interest in learning of 16 different health and fitness attributes, men were more interested than women were in learning about their muscle mass, running speed, vertical jump height, and ball throwing ability. Women were only more interested in learning about their flexibility.
When inquiring about their willingness to undergo 18 different test procedures, men were more willing to run or cycle until exhaustion, compete in an obstacle course task, receive electrical shocks, and complete strength training exercise that induces muscle soreness. Women were only more willing to complete an online survey about exercise.
As for their willingness to engage in diet or exercise programs, men were more willing to take a new muscle-building supplement, whereas women were more eager to partake in exercise programs that involved stretching, group aerobics, and home-based exercises accompanied by online coaching. In line with these findings, when asked to rate the appeal of various types of exercise, women found stretching, yoga, dancing, walking, and group aerobics more appealing than men, who preferred weightlifting and golf.
Finally, we sought to understand the various aspects of the overall research process that men and women deemed important in their decision to participate in a study. Of the 17 aspects examined, none were weighed more heavily by men. Women, by contrast, weighed many aspects of the research process more heavily than men, including:
Invasiveness of study procedures
Pain associated with study procedures
Possible side effects of study procedures
Amount of time required to complete study procedures
Confidence in one’s ability to complete study procedures
Potential anxiety that one might be experience during the research
Personal health status
Type of facility where the research is being conducted
Implications of the study results for society
Results in Perspective
Our results confirm much of what is already known about sex differences in psychology. For example, the observed sex differences in willingness to participate in certain types of exercise for research are broadly aligned with sex differences in everyday observed participation in these activities. Moreover, many of the fitness attributes that men prefer to be measured on are ones in which better performance would affirm their masculinity (e.g., muscle mass amount, muscle power). Conversely, women reported considerable interest in flexibility assessments and involvement in activities like stretching, yoga, dance, and group aerobics, which may validate their femininity.
Our findings align with previous studies indicating men’s increased inclination towards challenge and competition, women’s generally higher anxiety levels, a lower perceived self-competence in sports and motor skills among women, and heightened pain sensitivity and a greater self-reported fear of pain among women compared to men.
A key point in our analysis is that many of the sex differences we observed are large enough to explain sex discrepancies in participation in exercise science studies. Of the 172 survey items we explored, 29 percent revealed a sex difference large enough to explain a male/female representation of at least 60/40. Thus, the most important take away from our study is that 50/50 male/female representation should not necessarily be expected in exercise and sports science research.
In addition, it is important to acknowledge that there are other valid reasons why more men than women may participate in exercise studies. For instance, research in this field often pertains to injuries or diseases, which men and women exhibit differential susceptibility towards. Furthermore, researchers might have concerns about unintentionally exposing a fetus to potential harm, or the influence of the menstrual cycle on study results (a perhaps unnecessary concern).
Broader Implications for Exercise Science
Some exercise scientists seem unable to understand that a sex difference in research representation cannot be automatically interpreted to mean bias against women. The inability to grasp such a fundamental concept of data interpretation, namely, the notion that an observed difference does not reveal the causative factors of that difference, has broader implications in the discourse surrounding exercise and sports science.
For instance, editors of the British Journal of Sports Medicine continue to push the idea that “implicit bias” or “unconscious bias” against women pervades the discipline. This purported bias is alleged to extend beyond the realm of research representation, encroaching on the area of conference speaker representation as well. In addition to ignoring the potential impact of the factors discussed above, these assertions distort the evidence on sex bias. This evidence shows that the implicit association test and similar tools do not predict discriminatory behavior, that stereotype threat is not a reliable phenomenon in females, and that in most areas of career advancement female scientists do not face sex-based discrimination.
Furthermore, failing to recognize that individual preferences for specific kinds of physical exercise could influence the disparities in physical activity rates among various demographic groups, including the difference between men and women, has led exercise scientists in the American College of Sports Medicine to campaign for “equity in physical activity.” This campaign seeks to create identical physical activity rates among all demographic groups. How? By acting on social or structural factors, such as bias or discrimination, that campaigners believe are the root causes of observed group differences in physical activity participation (see our critique of this campaign here).
Be Skeptical About Claims of ‘Underrepresentation’
Clarifying the factors that contribute to sex disparities in research representations is important because inaccurate claims about representation have been made in the past and have had major consequences. For instance, the Office for Research on Women’s Health was established within the National Institutes of Health (NIH) in 1990, predicated on allegations of the “widespread exclusion of women in clinical trials.” This assertion was later debunked, and annual reports from the Office reveal that women constitute 55-60 percent of all participants in NIH-funded clinical trials each year.
Despite these statistics, this Office, which continues to operate at the expense of taxpayers, states that even though “roughly half” of NIH-funded clinical trial participants are women, a “substantial underrepresentation of women in clinical trials persists in multiple disease categories.” Meanwhile, there has been no parallel initiative to establish an office for research on men’s health within the NIH, even as men’s life expectancy in the U.S. is on average six years shorter than that of women.
Relatedly, in the exercise science literature, a claim was made that no female-only exercise training studies had ever been published in the seminal exercise journal Research Quarterly before 1975. We refuted this claim after meticulously searching the archives of the journal, which date back to 1930. We found that 33 female-only exercise training studies (4,960 female participants) were published in the journal between 1930 and 1975.
These experiences inform our understanding and instruct us to approach claims of female “underrepresentation” in research with a healthy dose of skepticism. Such assertions may be underpinned by political agendas or a broader refusal to consider that differences in representation can have causes other than bias against women. Our survey study identified several alternative causes.
In fact, we believe our results can, to a large extent, now answer the question first posed by Costello and colleagues in 2014: “Where are all the female participants in sports and exercise medicine research?”
Many women are doing things they find more appealing or less distressing than participating in sports and exercise medicine research!
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