Category Archives: engagement

The Olympics, sex, and gender in the physiology classroom
The recent Tokyo Olympic Games present an opportunity for a number of intriguing discussions in a physiology classroom.  Typical discussion topics around the Olympic Games involve muscle strength, muscle power, aerobic fitness, bioenergetics, and a number of other physiological factors that determine athletic performance.  Coronavirus, immunity, disease transmission, and similar topics may be unique areas of discussion related to the Tokyo Olympic Games.  Another topic that has been prevalent in the news for the Tokyo Olympic Games is the role of sex and gender in athletic competition.

Before and during the Tokyo Olympic Games several athletes were featured in news headlines due to either gender identity or differences of sexual development (DSD, also sometimes called disorders of sexual development).  Male-to-female transgender athletes competing in women’s sports in the Tokyo Olympic Games include weightlifter Laurel Hubbard, archer Stephanie Barrett, cyclist Chelsea Wolfe, soccer player Quinn, and volleyball player Tifanny Abreu, (1, 2).  There have also been news stories about Caster Semenya, Christine Mboma, and Beatrice Masilingi being ineligible to participate in the Olympics due to their DSD causing their serum testosterone concentrations to be above the allowed limits for female athletes (3, 4).  In addition to physiology sex and gender are interwoven with culture, religion, and politics, so how to discuss sex and gender in the physiology classroom needs to be carefully considered by each instructor depending on the campus climate, policies, and individual comfort level with walking into these potential minefields.  However, sex and gender in sports are very appropriate topics to discuss from a physiological perspective.

Although sex and gender have been used interchangeably in common conversation and in the scientific literature, the American Psychological Association defines sex as “physical and biological traits that distinguish between males and females” (5) whereas gender “implies the psychological, behavioral, social, and cultural aspects of being male or female (i.e., masculinity or femininity)” (6).  Using these definitions can be helpful to draw a clear distinction between gender (and/or gender identity) as a social construct and sex as a biological variable, which can help focus the discussion on physiology.

As reviewed by Mazure and Jones (7) since 1993 the NIH puts a priority on funding research that includes women as well as men in clinical studies and includes an analysis of the results by sex or gender.  Mazure and Jones (7) also summarized a comprehensive 2001 Institute of Medicine sponsored evaluation that concluded that every cell has a sex.  A 2021 Endocrine Society scientific statement provides considerable information on the biological basis of human sexual dimorphism, disorders of sexual development, and lack of a known biological underpinning for gender identity (8).  On August 12, 2021 a PubMed search using the term “Sex Matters” (in quotation marks) returned 179 results, with many of the linked papers demonstrating the importance of sex for health, disease, and overall biological function (without quotation marks there were 10,979 results).  Given that there have been various discussions in the news media and across social media blurring the distinction between sex and gender, it is very important that students in physiology understand that sex in humans is an important biologically dimorphic trait of male or female.

Relevant to a discussion of the Olympic Games, the differences in performance between male and female running has been analyzed for world’s best and world’s 100th best (9), annual world’s best performance (10), world record performance (11-13), Olympic and elite performance (13-16), High School performance in CA, FL, MN, NY, and WA (17), and 100 all-time best Norwegian youth performance (18).  Hilton and Lundberg (19) also provided an excellent review of the large differences in athletic performance between men and women in numerous sports.  Overall, by mid-puberty males outperform comparably aged and trained females by 10-60%, depending on the sport (see figure 1 of Hilton and Lundberg, reproduced here with no changes under the Creative Commons license


Hilton and Lundberg (19) also reviewed the present state of research regarding the effects of male-to-female hormone treatment on muscle strength and body composition and concluded that men typically have 45% more muscle mass than women, and male-to-female hormone treatment reduces muscle mass by ~5%.  These authors also concluded that men typically have 30-60% higher muscle strength than women, and male-to-female hormone treatment reduces muscle strength by 0-9%.  Overall, Hilton and Lundberg (19) conclude that transwomen retain considerable advantages over cisgender women even after 1-3 years of male-to-female hormone treatment.  Harper at al. (20) also reviewed the research regarding the effects of male-to-female hormone treatment on muscle strength and body composition and came to the same conclusions as Hilton and Lundberg.  Harper et al. (20) further concluded that male-to-female hormone treatment eliminates the difference in hemoglobin concentrations between cisgender men and women.  In a single research project, Roberts et al. (21) observed that before transition male-to-female members in the US Air Force completed a 1.5 mile running fitness test 21% faster than comparably aged cisgender women.  After 2.5 years of male-to-female hormone treatment the transwomen completed the 1.5 mile running fitness test 12% faster than comparably aged cisgender women. (Figure 1 Hilton and Lundberg)

All of the previously mentioned information is important to consider when asking if transwomen can be fairly and safely included in women’s sports.  It is also important to note that the effects of male-to-female hormone treatment on important determinants of athletic performance remain largely unknown.  Measurements of VO2max in transwomen using direct or indirect calorimetry are not available.  Measurements of muscle strength in standard lifts (e.g. bench press, leg press, squat, deadlift, etc.) in transwomen are not available.  Nor have there been evaluations of the effects of male-to-female hormone therapy on agility, flexibility, or reaction time.  There has been no controlled research evaluating how male-to-female hormone treatment influences the adaptations to aerobic or resistance training.  And there are only anecdotal reports of the competitive athletic performance of transwomen before and after using male-to-female hormone treatment.

The safe and fair inclusion of transgender athletes and athletes with DSD in women’s sports is a topic being debated in many states and countries, and by many sporting organizations including the International Olympic Committee.  In the end, whether it is safe and fair to include transgender athletes and athletes with DSD in women’s sports comes down a few facts that can be extrapolated, lots of opinions, and an interesting but complicated discussion.  This is a worthwhile discussion in a physiology classroom because it allows a good review of the biologically dimorphic nature of human sex.  However, the safe and fair inclusion of transgender athletes and athletes with DSD in women’s sports is also a discussion that should be approached with caution due to the many opinions this topic entails that reside outside of physiology.



1.    The Economist explains: Why are transgender Olympians proving so controversial? The Economist. [Accessed: August 12, 2021, 2021].

2.    Pruitt-Young S. Live Updates: The Tokyo Olympics Canadian Soccer Player Quinn Becomes The First Out Trans And Nonbinary Gold Medalist NPR. [Accessed: August 12, 2021, 2021].

3.    The Clock Ticks on Caster Semenya’s Olympic Career [Accessed: August 12, 2021, 2021].

4.    Tokyo 2020: Two Namibian Olympic medal contenders ruled ineligible for women’s 400m due to naturally high testosterone levels CNN. [Accessed: August 21, 2021, 2021].

5.    APA Dictionary of Psychology: sex. American Psychological Association. [Accessed: August 12, 2021, 2021].

6.    APA Dictionary of Psychology: gender. American Psychological Association. [Accessed: August 12, 2021, 2021].

7.    Mazure CM, and Jones DP. Twenty years and still counting: including women as participants and studying sex and gender in biomedical research. BMC Womens Health 15: 94, 2015.

8.    Bhargava A, Arnold AP, Bangasser DA, Denton KM, Gupta A, Hilliard Krause LM, Mayer EA, McCarthy M, Miller WL, Raznahan A, and Verma R. Considering Sex as a Biological Variable in Basic and Clinical Studies: An Endocrine Society Scientific Statement. Endocr Rev 2021.

9.    Sparling PB, O’Donnell EM, and Snow TK. The gender difference in distance running performance has plateaued: an analysis of world rankings from 1980 to 1996. Med Sci Sports Exerc 30: 1725-1729, 1998.

10.  Tang L, Ding W, and Liu C. Scaling Invariance of Sports Sex Gap. Front Physiol 11: 606769, 2020.

11.  Cheuvront SN, Carter R, Deruisseau KC, and Moffatt RJ. Running performance differences between men and women:an update. Sports Med 35: 1017-1024, 2005.

12.  Thibault V, Guillaume M, Berthelot G, Helou NE, Schaal K, Quinquis L, Nassif H, Tafflet M, Escolano S, Hermine O, and Toussaint JF. Women and Men in Sport Performance: The Gender Gap has not Evolved since 1983. J Sports Sci Med 9: 214-223, 2010.

13.  Sandbakk O, Solli GS, and Holmberg HC. Sex Differences in World-Record Performance: The Influence of Sport Discipline and Competition Duration. Int J Sports Physiol Perform 13: 2-8, 2018.

14.  Millard-Stafford M, Swanson AE, and Wittbrodt MT. Nature Versus Nurture: Have Performance Gaps Between Men and Women Reached an Asymptote? Int J Sports Physiol Perform 13: 530-535, 2018.

15.  Seiler S, De Koning JJ, and Foster C. The fall and rise of the gender difference in elite anaerobic performance 1952-2006. Med Sci Sports Exerc 39: 534-540, 2007.

16.  Nuell S, Illera-Dominguez V, Carmona G, Alomar X, Padulles JM, Lloret M, and Cadefau JA. Sex differences in thigh muscle volumes, sprint performance and mechanical properties in national-level sprinters. PLoS One 14: e0224862, 2019.

17.  Higerd GA. Assessing the Potential Transgender Impact on Girl Champions in American High School Track and Field. In: Sports Management. PQDT Open: United States Sports Academy, 2020, p. 168.

18.  Tonnessen E, Svendsen IS, Olsen IC, Guttormsen A, and Haugen T. Performance development in adolescent track and field athletes according to age, sex and sport discipline. PLoS One 10: e0129014, 2015.

19.  Hilton EN, and Lundberg TR. Transgender Women in the Female Category of Sport: Perspectives on Testosterone Suppression and Performance Advantage. Sports Med 2020.

20.  Harper J, O’Donnell E, Sorouri Khorashad B, McDermott H, and Witcomb GL. How does hormone transition in transgender women change body composition, muscle strength and haemoglobin? Systematic review with a focus on the implications for sport participation. Br J Sports Med 2021.

21.  Roberts TA, Smalley J, and Ahrendt D. Effect of gender affirming hormones on athletic performance in transwomen and transmen: implications for sporting organisations and legislators. Br J Sports Med 2020.

Dr. Greg Brown is a Professor of Exercise Science in the Department of Kinesiology and Sport Sciences at the University of Nebraska at Kearney where he has been a faculty member since 2004. He is also the Director of the General Studies program at the University of Nebraska at Kearney. He earned a Bachelor of Science in Physical Education (pre-Physical Therapy emphasis) from Utah State University in 1997, a Master of Science in Exercise and Sport Science (Exercise Physiology Emphasis) from Iowa State University in 1999, and a Doctorate of Philosophy in Health and Human Performance (Biological Basis of Health & Human Performance emphasis) from Iowa State University in 2002. He is a Fellow of the American College of Sports Medicine and an American College of Sports Medicine Certified Exercise Physiologist.
Less is more – focusing on the core concepts

When it comes to teaching a subject in depth and breadth, an instructor may face the challenges of limited time versus unlimited contents. To this end, the instructor may focus on covering as much as possible material in a lecture, or on the key concepts that help prioritize contents and overarch a myriad of information. The former strategy is highly content-centered and can be overwhelming to both the instructor and students, and in fact, studies have shown that instruction time is not necessarily proportional to learning outcome [1]. By contrast, the latter strategy makes time for the instructor and student to interact, discuss, and apply the key concepts to problem solving activities, which fosters an active and interactive learning environment. In line with the evidence showing that students benefit more from an active and interactive learning experience [2], educators have called for less coverage and more inquiry aiming high beyond just the facts so that student’s learning can be enhanced by talking, writing, and collaborating [3-4].

How can one effectively prioritize contents by focusing on the key concepts pertaining to the latter strategy? One of the possible ways is to use learning objectives or anticipated learning outcomes to navigate content prioritization. It is overwhelming to start with materials for teaching planning due to fast growing research and knowledge explosion. However, using a backward design may change the game. Backward design of a course starts with developing clear learning objectives, which aligns selection of lecture contents with anticipated learning outcomes [5-6]. For instance, to accomplish the objective of building students’ critical thinking skills, an instructor will strategically plan time for not only covering materials but also information processing and application. Other than concentrating student learning on facts only, the class will be fueled by problem-based collaborative learning. To this end, it is critical for the instructor to elaborate the key principles or concepts, the very guides students need to address complex problems that demand more than simple factual answers. The collection of facts relevant to the class can be provided as supplemental information or resources for students to look up for problem solving, while it can limit student learning as a major commitment of memorization.

Mastery of basic principles plus being detail-oriented is required for success in experimentation and authentic research in a lab course [7]. To this end, students are expected to pay attention to experimental details in addition to core concepts, raising the question as to how course contents can be prioritized. First, the strategy of backward design still applies. Secondly, the learning objectives or anticipated learning outcomes can be defined such that they focus on core principles and transferrable or interchangeable skills. For instance, the course Laboratory Techniques in Molecular Nutrition covers several sets of lab techniques, one of which is immunoassays. Immunoassays represent a set of methods based on antigen-antibody binding reactions, including Western blotting (WB), immunoprecipitation (IP), co-immunoprecipitation (co-IP), chromatin immunoprecipitation (ChIP), ChIP sequencing (ChIPsec), immunohistochemistry (IHC), immunocytochemistry (ICC), and enzyme-linked immunosorbent assay (ELISA). Each method may take 1-2 weeks (5 hours/week) to cover the principles and operational procedures, and the set of immunoassays alone may occupy a semester. Obviously, it is very challenging to elaborate on each of the immunoassays within a semester given the limited time and resources, plus the needs to cover non-immunoassay techniques. However, it is practical for students to learn about the techniques within 4-5 weeks (5 hours/week) with a prioritized focus by elaborating on the core concepts shared by the eight immunoassays and contrasting the major differences among them. The core principles are shared by all the immunoassays regarding immobilization, blocking, immunobinding, washing, and detection processes. Yet, they are different in assay microenvironments including the solid phases, blocking solutions, antibodies, targets of interest, washing solutions, and detection reagents and instruments. Priority can be given to elaborating the core concepts and major differences (1-2 weeks) and to practicing the most used and accessible immunoassays such as WB, IP, and ELISA (3 weeks).

Practically, use of flipped classrooms can further enhance students’ mastery of key concepts and their ability to apply the concepts to solving problems. In a flipped classroom, the instructor lectures less in class but the course materials and recorded lectures are uploaded to the course management site (e.g., Canvas) for students to study in advance. Students tend to learn more through problem-solving activities with the instructor and peers in class that build critical thinking skills. As such, the learning outcomes can be increased and go beyond the contents by enhancing students’ critical thinking skills, which will benefit their lifelong learning after college.

Taken together, focusing on facts less in class but targeting core concepts and knowledge application more may serve as an effective strategy to build students’ critical thinking skills. The “less” by no means refers to an easy class. Instead, both the instructor and students spend more time outside the class preparing and studying course materials. This is to prepare everyone for more higher-order-thinking activities (e.g., analysis, evaluation, and application) in class. The “less” for “more” pedagogy may benefit student’s lifelong learning experience.


References and further reading

[1] Andersen SC, Humlum MK, Nandrup AB. Increasing instruction time in school does increase learning.

Proc Natl Acad Sci USA. 2016 Jul 5;113(27):7481-4.

[2] Dolan EL, Collins JP. We must teach more effectively: here are four ways to get started. Mol Biol Cell. 2015 Jun 15;26(12):2151-5.

[3] Luckie DB, Aubry JR, Marengo BJ, Rivkin AM, Foos LA, Maleszewski JJ. Less teaching, more learning: 10-yr study supports increasing student learning through less coverage and more inquiry. Adv Physiol Educ. 2012 Dec;36(4):325-35.

[4] DiCarlo SE. Too much content, not enough thinking, and too little fun! Adv Physiol Educ. 2009 Dec;33(4):257-64.

[5] Allen D, Tanner K. Putting the horse back in front of the cart: using visions and decisions about high-quality learning experiences to drive course design. CBE Life Sci Educ. 2007, 6(2): 85–89

[6] Hills M, Harcombe K, Bernstein N. Using anticipated learning outcomes for backward design of a molecular cell biology Course-based Undergraduate Research Experience. Biochem Mol Biol Educ. 2020 Jul;48(4):311-319.

[7] DiCarlo SE. Cell biology should be taught as science is practiced. Nat Rev Mol Cell Biol. 2006 Apr;7(4):290-6.

Dr. Zhiyong Cheng received his PhD in Analytical Biochemistry from Peking University, after which he conducted postdoctoral research at the University of Michigan (Ann Arbor) and Harvard Medical School. Dr. Cheng is now an Assistant Professor of Nutritional Science at the University of Florida. He has taught several undergraduate- and graduate-level courses (lectures and lab) in human nutrition and metabolism (including metabolic physiology). As the principal investigator in a research lab studying metabolic diseases (obesity and type 2 diabetes), Dr. Cheng has been actively developing and implementing new pedagogical approaches to build students’ critical thinking and problem-solving skills.