 The Tokyo Olympics just ended last weekend, and this was the first time that an openly transgender athlete competed at the Games. Laurel Hubbard is a transgender woman who competed in women's weightlifting, and this has sparked controversy over the fairness of allowing a transgender woman to compete with cisgender women, otherwise referred to as biological females. And that's exactly what we'll be getting into in this video. Unlike a lot of the videos that I make, a lot of you are probably coming into this video with strong opinions one way or the other already. I encourage you to keep an open mind, just as I strive to do when researching every video that I make. For the most part, I'm going to be citing research for pretty much the whole video, but at the end of the video, I will be giving my research-based opinion on the matter. Now, this is a cycling YouTube channel, so why am I talking about an Olympic weightlifter? Because you finally ran out of shit to talk about? Well, this controversy has also cropped up in the cycling world as well. For example, transgender athlete Rachel McKinnon has won two world titles and the world record in the 200-meter match sprint at the Masters Track Cycling World Championships. And these are just two examples of many instances where male to female trans athletes have competed with women and the internet has blown up over it. Transgender athletes are allowed to compete at the Olympics, but there are certain criteria that they must meet in order to be eligible. From the International Olympic Committee's consensus meeting on sex reassignment and hyper-androgenism, female to male trans athletes can compete with males without restriction, but male to female athletes can only compete with females under the following conditions. The athlete has declared her female identity for at least four years, and the athlete must demonstrate that her serum testosterone levels have been under 10 nanomoles per liter for at least 12 months prior to competition. Surgical anatomical changes are not required to compete. The UCI, which is the international governing body for cycling events, has taken an even stricter stance here, requiring that transgender women keep their serum testosterone levels below 5 nanomoles per liter. For the vast majority of us, those numbers probably don't mean a whole lot. So here's some context. The normal range for serum testosterone for men starts at 10 nanomoles per liter, which is that threshold set by the IOC, and goes up to about 38 nanomoles per liter. For women, the range is from 0.5 nanomoles per liter to 2.5 nanomoles per liter. So while the rules set by the IOC and the UCI require that trans-female athletes have testosterone levels below the normal range for men, they could still train and compete at levels above the normal range for women. The questions that arise here are, is this testosterone threshold a fair benchmark to assess whether or not transgender women are on an even playing field with their cisgender counterparts? And also, is testosterone the only advantage that men have over women? After all, it is the only metric that the IOC and the UCI are using to assess fairness. This review article on transgender women in female sports notes a number of physical attributes that are major parameters underpinning the male performance advantage. On average, men have 45% more lean body mass yet 30% less body fat percentage, 33% more lower body muscle mass, 40% more upper body muscle mass, 57% more grip strength, 54% more knee extension torque, longer bones, narrower pelvis, greater force and stiffness of the tendons, 50% higher VO2 max in terms of absolute values, and 25% higher in terms of relative values, 48% higher maximal pulmonary ventilation, larger hearts with a higher cardiac output and stroke volume and finally a higher hemoglobin concentration. There's clearly a long list of physiological reasons why men are generally better at sports than women. Now some of these advantages will be mitigated by hormone replacement therapy or a lowering of testosterone level, for example, muscle mass and body fat percentage. However, some of these advantages won't be affected at all, for example, bone length, height, and dimensions of the pelvis. So exactly how much of an advantage do these physiological differences between the sexes give men? The review further lays out the male performance advantage across a variety of sports. Women sports like running, swimming, and cycling are on the low end with a 10-13% advantage. Downhill mountain biking, tennis serve, golf driver speed, and pole vaulting are all in the 16-22% range, volleyball serve and weightlifting are up to 29-34%, and baseball pitch and field hockey drag flip are as high as 50% or more. This is the performance advantage that men have over women in sports, and if you were to take a man who's received no hormone treatment and put them up against women, it would be unfair. No one is arguing that. It's the whole reason why we have sex segregated sports in the first place. Yeah, that, and also, if I competed in the women's category, it'd be pretty distracting for my competitors and honestly, might cause some crashes. Alright, with that, let's get back to the originally posed question. Does lowering testosterone levels erase this advantage? This study on muscle strength, size, and composition following 12 months of gender-affirming treatment looked at both trans women and trans men, testing leg muscle strength before and after 12 months of hormone replacement. Thigh muscle volume was increased by 15% in trans men, while trans women saw a decrease of 5%. Okay, so when women transition to men and take testosterone, there's a substantial increase in muscle mass, 15% according to this study. But when men transition to women and suppress testosterone, the change is not nearly as dramatic around a decrease of 5%. It is a decrease nonetheless, though. The more applicable question for sports is, what did these changes do to their strength? The trans men increased strength over the study period, no surprises there. What is surprising is that the trans women generally maintained or slightly increased strength. On top of this, despite the robust increases in muscle mass and strength in trans men, the trans women were still stronger and had more muscle mass following 12 months of treatment. These subjects reported no change in physical activity level, and their testosterone levels were well below the threshold set by the IOC and the UCI, and within the typical range for women. This is evidence against the notion that trans women's advantage is erased simply by lowering their testosterone levels. In fact, if you had a group of trans men compete against a group of trans women, it may still not be an even playing field. The point here is that the gap is large, and this is not just one study coming to this conclusion. Similar studies show the same thing, a small decrease in strength in trans women, a large increase in strength in trans men, and despite this, trans women still outperformed the trans men after hormone replacement. Coming back to this review, they echo these conclusions, stating that the muscular advantage enjoyed by transgender women is only minimally reduced when testosterone is suppressed. The research does not seem to indicate that hormone replacement is sufficient to get rid of the advantage that transgender women have in strength. That being said, one issue that I do have with these studies is that they all seem to test untrained individuals as opposed to athletes, which we know can have an effect on studies that test changes in physical performance. It's also important to mention, especially for us as cyclists, that there aren't really any good studies on how transition affects endurance performance. The only one that exists is this one on race times for transgender runners, which looked at race times at various distances in transgender women before and after transition. The results showed that the transgender women had remarkably similar age-graded scores in both the male and female gender. Age-grading is a way of comparing performances of all ages and sexes. According to this study, this would mean that transgender women could be at the same level as cisgender women in these types of events. This study is not without its flaws, though. From the study itself, the races compared had a long time period between them, and only two of the eight runners reported stable training patterns over this time range. Going back to this review, they agree on the value of this study, stating that factors affecting performance in the interim, including training and injury, were uncontrolled for periods of years to decades, and there were uncertainties regarding which race times were self-reported versus which race times were actually reported and verified, and factors such as standardization of race course and weather conditions were unaccounted for. That study was far from high quality, and given that it's the only study we have that comes to that conclusion, it would be quite a leap to say conclusively that transgender women have no advantage over cisgender women in sports like running, swimming, cycling, etc., based on that study alone. What it can do is reinforce a point that I touched on earlier in the video, which is that the gap in performance between men and women in endurance sports is much lower than the gap in strength-based sports. We're talking 10 to 13% versus 30, 40, or 50%. Given this, it is perhaps more likely that an endurance race such as the marathon between transgender and cisgender women could be fair. Going back to this review, they state that circulating hemoglobin, which can affect endurance performance, are reported as 12% higher in males compared with females, and hemoglobin levels appear to decrease by 11-14% with cross hormone therapy in transgender women. Oxygen carrying capacity is also most likely reduced with testosterone suppression. What it really comes down to is that we need more data. The effects of testosterone suppression on VO2 max, left ventricular size, stroke volume, blood volume, cardiac output, lactate threshold, and exercise economy, all of which are important determinants of endurance performance, remain unknown. Until more research comes out about how testosterone suppression affects endurance sports performance, it's really hard to make a conclusion either way right now. So given the data that we do have, what conclusions can we make? Well, evidence that reduced testosterone in trans women results in them losing their 10-50% performance advantage is simply lacking. For strength-based sports like weightlifting, there's really no question. Sure the research is limited, but all the studies are pointing in the same direction, which is that testosterone suppression does not erase the transgender female's strength advantage. And in fact, it really doesn't even come close. Endurance sports are a different story though, because the research is so limited, and the one study that we do have, albeit flawed, did show that potentially trans women could compete with cis women fairly. Nonetheless, even if we do find that endurance sports performance is the same between transgender and cisgender women, which is unlikely seeing as strength is still a relevant factor in these sports, there is still always the potential for races to come down to a sprint finish. And in cycling, particularly road cycling and track cycling, that's actually the norm, not the exception. When assessing whether or not trans women would have an advantage in sprinting, well that brings us back to the data that we have on strength and explosiveness. And trans women would have a clear advantage, and therefore the competition would be unfair. Races are often won by razor-thin margins, and even the slightest unfair advantage could be the difference between winning and not even making the podium. However, insignificant that difference may seem to us. Tell me about it, dude. I forgot to shave my legs before the crit last weekend, and that little bit of extra aero drag is the reason why I got dropped 15 minutes in instead of pulling out the win. Next time, I guess. Therefore, there is a heavy burden of proof placed on those who claim that transgender women competing in endurance sports with cisgender women is fair, and at this point in time, we're nowhere close to meeting that burden of proof. But who knows, maybe in the future as we get more research, that could change. If you strip away the politics on both sides of this argument, this is essentially what it boils down to. In sports, we value both fairness and inclusion. We want people to feel included and be included in sports if that's what they want to do. And research shows that trans athletes have faced real struggles in this area, which is something we should fight to change. But we also want sports to be fair. This is why we don't allow doping. It's why we have different age categories and weight categories in the Paralympics. We want to see people compete on an even playing field. When you ask, should trans women be allowed to compete in women's sports, what you're really asking is which do you value more, inclusion or fairness? Different people will have different answers to this question, but the International Olympic Committee's answer is that they value fairness more. The overriding sporting objective is and remains the guarantee of fair competition. Restrictions on participation are appropriate to the extent that they are necessary and proportionate to the achievement of that objective. The IOC is stating that they restrict participation in order to preserve fairness. Now other governing bodies can have different rules about how much they value inclusion versus fairness, but it's pretty clear from the data that the current IOC guidelines on transgender athletes does not support this fairness objective as they claim. And finally, one side that I often see being left out of this debate is the perspective of the cisgender women that have to compete against transgender women. After all, it is these women who could potentially be losing out on wins, podium spots, medals, Olympic spots, national team spots, sponsorships and endorsements because of these rules. Luckily, I found a study that did seek out this perspective. This study polled female Olympians from this year's games and came up with these main findings. These athletes thought both female and transgender athletes should be fairly included in elite sport. However, there was also unanimous agreement that there is not enough scientific evidence to show no competitive advantage for transgender women. The women also unanimously agreed that the International Olympic Committee should revisit the rules and scientific evidence for transgender inclusion in female categories. And finally, the majority of athletes felt that they could not ask questions or discuss this issue without being accused of transphobia. That wraps up this video, but I want to hear from you. What do you think a solution to this problem is? Should trans women just compete with cis women? Should they have their own category? Should there be an open category? Should the testosterone limit be reduced further? Or perhaps something else? Let me know down in the comments. If you enjoyed this video, be sure to give it a like, subscribe for more science-based cycling videos just like this one, and share this video with your cycling friends. And your sports fan friends as well. I'll see you in the next one.