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To start now. Thank you all for joining me for the last tutorial of the seating series. Um Today we're gonna be covering nutritional interventions or other kind of the nutritional side of um relative energy deficiency syndrome in sport or reds. Um Right. So today, sorry, let me just get the slides. We're gonna first before going into REDS, just have a discussion about bone health um primarily because it is the first and most severely um affected physiological um function by relative energy deficiency syndrome. So we're just gonna look at a few nutrients required for bone health. Um looking at the importance of protein intake and Vitamin D and this will involve a critical analysis and then just touch on calcium as well. And then we're gonna dive into reds, looking at energy balance, energy availability, what reds is and then strategies to avoid or overcome reds. Um As usual, I'm gonna try and monitor the chat as well throughout, but there will be time for questions at the end as usual, right? So bone health, there are several key nutrients required for bone health. It is a very multifactorial system, but some of the major ones that you've probably heard of include calcium, protein, magnesium, phosphorus, Vitamin D potassium and fluoride. And as you can see in the diagram on the screen, these are nutrients that we get primarily from food sources. It's not something that we need to be particularly supplementing unless obviously you're following a diet that could be deficient. Um for example, if you have, you consume no dairy products whatsoever, calcium might be something that you want to look out for. Um But as a general rule, most of these nutrients can be gotten easily from food sources. Give. Now a high protein intake um has been shown to increase bone mineral density, thereby decrease decreasing fracture risk. Now, bone mineral density is simply a measure of the concentration of minerals such as those that we just saw in um a certain volume of bone. And it's a marker for um bone health and bone strength and therefore resistance from f to fractures. Now, we've touched on protein a lot on this teaching series with regards to muscle, but similarly, it has um so called anaboly effect as you could say on bones. Now, one such way it's similar pathway like that seen in muscle is by increasing growth hormone and this acts on the I GF one axis which stimulates bone formation. It also improves intestinal calcium absorption which suppresses P THP th or parathyroid hormone is a hormone that is released um when plasma calcium is low and the role of P TH is really to make, maintain um calcium concentrations. And so, if plasma calcium is low because you're not consuming enough calcium, for example, um then it will actually break down bone to release the calcium in the bones. And thereby you're actually decreasing the integrity of the bone structure. So, by improving intestinal calcium absorption, you reduce P TH action, thereby reducing skeletal turnover or the breakdown of bone. Um and dietary protein also helps with protein synthesis. And amongst the proteins that are synthesized are collagens and noncollagen bone matrix proteins which are important in the architecture of bone as well. And so all of these help promote bone density and strength which prevents fractures. Now, protein also acts on muscles, both muscle size and muscle strength and these have independent effects because by increasing the muscle size, you're increasing the weight and the pressure on bone from the surrounding muscle, thereby producing another stimulus for muscle growth. Because weight and tension is a um stimulus for bone formation, which is why heavy residence exercise is also a good idea for increasing or maintaining bone mineral density. Um And by increasing muscle strength, you're more stable, you're decreasing your risk of falls, thereby directly decreasing bone fractures. So, protein acts on um bone health via numerous pathways. Now, Vitamin D has been shown in many studies to have a positive effect on bone um or on preventing fractures and this is what the study showed. So, they looked at division one athletes and they followed them for eight weeks. And what they did is that they measured their plasma Vitamin D levels and the athletes who were Vitamin D deficient, which was um classified as less than 30 nanograms uh per deciliter of blood, um of Vitamin D They were supplemented with 50,000 I US of um Vitamin D per week. And I use the measurement unit that we use. And um they also then, so that was the 2015 to 2016 cohort that we see in light gray. What they also did is they did a five year retrospective chart review and that's what we see in the dark gray. So they made the athletes that they followed are the light gray columns and they are the ones who were ensured were in the right Vitamin D range by giving supplements if needed. And they compared their stress fracture incidents during the 2015 to 2016 period compared to the number of um stress fractures in the previous five years when Vitamin D levels were not being managed essentially. And what we see circles in red is that the overall stress fracture incidence was dramatically reduced with this Vitamin D intervention. Now, another study done in female navy recruits found similar um results where they randomized the Navy recruits to either receiving 2000 mg of calcium plus 800 IU of Vitamin D per day or placebo. And there were about 700 participants per group, which is quite a big sample size. And they found that again, supplementing Vitamin D compared to placebo reduced the incidence of stress fractures. So it seems like Vitamin D supplementation prevents stress fractures. But this study didn't really find any effects. So they looked at 950 male athletes precompetition and they were competing in either indoor or outdoor high impact sports. And it doesn't, the results were not really concerned about whether they were doing indoor or outdoor sports. But on the X axis, we can see a range of Vitamin D levels. And what they showed is that actually there doesn't really seem to be much of a difference between the Vitamin D levels. So the athletes participating in high impact sports had higher measures of bone health compared to controls regardless of the Vitamin D status. Now, why am I be seeing this? Why might we be seeing these discrepancies? Um, so like last week, I thought I'd make a poll to ask you guys. Um, so just take a few minutes to try and answer. Um, as usual, these are all very plausible explanations. Um, the correct answer will simply be specific to these studies. Um, but it's just to get you thinking and having a look at the different possibilities and not just the ones that I'll be presenting about these studies. Ok. We've got three responses so far. I'll wait maybe 15 more seconds. Ok. Um, right. So it seems like most were in the two lower answers. So either different participant characteristics or different climates, as I said, all very possible answers. Um But let's look into what um we found in these studies. So one was difference in the variable measured. So the worms et al and lap all studies. So the two that found a positive effect of Vitamin D supplementation um measured stress fractures. Whereas Alison al, the ones who didn't find really an effect looked at bone mineral density by at score. Now, there's not necessarily a correlation between bone mineral density and stress fractures. Well, bone mineral density would suggest that you have a low risk of stress fractures. It also depends on the sport you're involved in and on many other factors. So it's not necessarily a direct correlation and differences in Vitamin D status. So, Williams et al looked at um supplementing with Vitamin D and Vitamin D deficient athletes. Um so preventing deficiencies, lab, et al supplemented Vitamin D and calcium, but they didn't actually measure the Vitamin D status at baseline. So some of the major deficient others may not have needed the Vitamin D in terms of looking at deficiencies or not. Um So it was just a standard supplementing or not supplementing protocol and finally, et al didn't supplement, they just looked at the serum Vitamin D status. Um So these can explain some of the reasons why they may have had different outcomes Um But again, traditional followup could have been a um possible reason as well. Um The dosages were different as we can see, some of them supplemented, some of them didn't even supplement. Um But yeah, but one thing that I want to underline here is that lab et al didn't just supplement Vitamin D They also supplemented calcium. And that is important because calcium is actually what is directly involved in the bone formation and bone um breakdown as we saw when serum calcium. So calcium in the blood is decreased, the hormone P th is secreted, which increases bone turn turnover, it it increases the resorption of bone, the breakdown of bone to release calcium into the bloodstream. And so calcium is actually what we really need to build bones and Vitamin D seems to actually help with the absorption of calcium. And so maybe the Vitamin D supplements are only useful if sufficient calcium is present. So you could be supplementing lots of Vitamin D But if you don't have enough calcium to actually build the bones and to reduce the signaling of PDH, then the Vitamin D might not actually be doing very much in terms of maintaining bone health. So that's just what I want to say about calcium as well. Um So calcium and Vitamin D together is the right combination, making sure that both are in the right ranges to ensure that calcium goes into the bones. And Vitamin D helps the absorption of calcium. Now, moving on to energy balance. Um So going on to the field of reads, energy balance is the amount of dietary energy added to or lost from the body's energy stores. After the body's physiological systems have done all their work for the day. And an easier way to say this is energy intake minus total energy expenditure. Now, if you're on a positive energy balance, you have a greater intake than energy expenditure, you have weight gain. And if you're in a negative energy balance, you burn more calories than you consume, you lose weight. Now, energy intake comes from macronutrients and there are four main ones with different caloric components. So alcohol, the most important macronutrient has seven calories per gram. Protein has four calories per gram fat, has nine calories per gram and carbohydrates have four calories per gram. So already with the same gram per gram comparison, you have different amounts of calories and it's um contributing to different extents to the calorie intake. Now, in terms of energy expenditure. So the other side of the equation, we have basal metabolic rate or B mr, this is the energy that your body consumes to simply stay alive. So the energy you use up to breathe the energy you use to digest for your heart to beat, um to look around, that's basal metabolic rate. So it's the calories you burn at rest really. Then you have the thermic effect of food. Um This is the energy the body consumes to digest foods. And this again varies for different macronutrients. So, as we touched on, I think, four or five weeks back, protein, for example, we saw on the previous side, protein and carbohydrates both have four calories per gram. But their thermic effect of food differs. The thermic effect of food of protein is about 30% greater than that of carbohydrates. Which means that when consuming 100 g of protein or consuming 100 g of carbs for the protein, about 70 of those calories are gonna stay in your body. The other 30 are being used to digest the protein. Whereas when you consume 100 g of carbs, 100 calories of carbs, sorry about five or 10 of those are being used to digest the carbs and the other 90 to 95 stay in your body. So that is another big consideration also in terms of the composition of food, then we have nonexercise activity, thermogenesis or meat. This is the energy you burn from moving around. Um things like walking to class, taking the stairs. Um, all essentially fidgeting, you know, tapping your foot during class. These are all neat. And then we have exercise activities in moensis or eat and this is programmed exercise. So if you go to the gym for an hour, that's eat, if you choose to go for a run for an hour that's eat, if it's a programmed exercise, that is eat and if it's not programmed, it's me. And I mean, it can be like a last-minute decision to go for a run that's still exercise activity, thrombogenesis. Um But these contribute to different extents to energy expenditure and I want you to just have a go at another little pole. Um Just which one do you think is the biggest contributor to daily energy show? OK. So we're seeing kind of mixed answers. Uh Most people went for B Mr basal metabolic rate. Um but we have some going for exercise activity, thermogenesis as well. Those are the two most popular. Um So let's have a look, B Mr um sorry, eat plus neat together, make up 25 to 50% of energy expenditure. And that obviously depends on how active you are and how much you exercise. Um thermic effect of food. 10% and B Mr 40 to 70% again, depending on the individual. So a big a person with a lot more muscle mass will have a greater percentage. Um coming from B Mr because muscle is the most metabolically active tissue in the body. Um but the split between B Mr and eat um in the answers I think is quite reasonable. Um Because although B Mr in the average person is the biggest contributor, if you're looking at athlete cohorts who are training every day, especially if you're looking at endurance athletes. Um the exercise activity thermogenesis can really, really increase dramatically. Um So yeah, a lot of differences in terms of the profession, the lifestyle and things like that. But as a general for the general population, B Mr is typically the greatest contributor. Now, when do we want to consider energy balance or when does it, I mean, we always want to consider energy balance, but when does it become a particular point of interest? Uh one is when you're trying to alter body composition while maintaining body mass, so say you're 80 kg, you want to stay at 80 kg, but you want to lose fat and increase muscle so that the proportion of each is changed in that 80 kg maximizing lean tissue gain during weight gain. So if you're on a bulk and you want to maximize the muscle gain as opposed to fat gain, minimizing lean tissue loss during weight reduction. And this goes back to the tutorial a few weeks ago about healthy weight loss. So making sure you maintain the muscle mass during a fat loss period, safe, fast weight loss again and maintaining energy balance with a high energy expenditure. And this is particularly relevant in the athlete po populations when they're entering a precompetition or a competition season where they need to increase their training, making sure that their energy intake is sufficiently high to match the energy that they are expending with their training. And this brings me to the topic of energy availability. So energy availability is a residual energy available to support an individual's body function. Once the expenditure of exercise is deducted from energy intake or in simpler terms, energy intake minus exercise, energy expenditure over fat free mass in kilograms and fat free mass again is usually a measure of muscle mass. So yeah, accounting for the calories, you're burning and exercise, how much is left over to maintain your bodily functions and these come in thresholds. So for a stable body mass, we're looking at about 45 kg per kilogram of fat free mass per day. And I just want to say before we go into this, this is not necessarily something um that somebody who's just trying to gain or lose weight. Um I wanna say this recreationally just because it's not out of athletic incentive. Um It's not numbers that we particularly need to work with. Um these, these are just kind of to give you an idea of really how small the difference in thresholds are which we're about to get into. Um But if you are trying to lose weight or gain weight um and making sure that energy availability is in a healthy range for you. Um This is not really something that you need to start calculating. Um it is quite difficult to calculate as well. Um But it's just again, it's in the scientific literature, it helps give an idea. Um So for single body mass, 45 kg, uh kilocalories per kilogram factory mass per day So if you want to gain weight, you need to go above that. And if you want to lose weight, you have to go below that. But note how for weight or fat loss, I put a lower margin. So you do not want to drop below 30 kg calories per kilogram of fat from mass per day of energy availability. And that is because that is when we enter the territory of low energy availability and that's where health consequences can arise. So low energy availability is any mismatch between energy intake and expenditure that leaves the body's totally energy needs unmet. So in other words, it's you're left with inadequate energy to support the functions required to maintain optimal health and performance. And as I said, it's traditionally defined as less than 30 calories per kilograms of fat free mass per day. Now, causes of low energy um availability are either you have insuffent energy intake and this can be due to poor eating habits, reduced, available eating time or disordered eating patterns. It can be excessive exercise, activity thermogenesis. So this is seen often in endurance athletes or if there are high training volumes or schedules, um or if additional physical activity is added to the schedule for weight regulation, or it can be a combination of both. And this thing can be either intentional for weight regulation purposes um through an athletic ince incentive or th because of a disordered incentive um or can be unintentional like failing to increase energy intake with increased energy activity, thermogenesis. Now, as I mentioned at the start, bone turnover is the first system to be affected by low energy availability and it's affected both in the bone formation and bone breakdown sides of the equation. So as I mentioned at the start, you have bone being built, bone and most tissues in the body are in a constant state of turnover. It's being built and broken down to make sure that the cells are healthy and not old and kind of dysfunctional. Um But what happens with low energy availability is that bone formation decreases. So, if we look at the left hand side, this study showed that as energy availability decreases from 45 which was the maintenance threshold to 30 which we said was kind of the lower margin of still healthy to under 30. We get an incremental decrease in bone formation and bone breakdown show the opposite trend where with as energy availability decreased. On the right hand side, we can see that going down to 20 to 10 calories per kilogram per day. Um We have a significant increase in bone breakdown. Um and this becomes particularly important when we consider the fact that a lot of amenorrheic athletes. So these are female athletes who have lost their menstrual cycle as a result of low energy availability, um have energy availabilities of about 16 calories per day which is extremely low and another thing to really keep in mind is that studies have shown that low energy availability coming from a reduced energy intake has more severe detrimental effects on bone bone turnover and general health, then if the low energy availability comes from increased exercise activity, thermogenesis, so a low energy intake seems to be particularly detrimental. And this again can link back to the fact that they're not getting enough of the key nutrients and not enough of the protein that are required to maintain bone health. And as I alluded to, there are severe hormonal changes in low energy availability, I'm not gonna go through them all and you don't have to know them all. It's more just that it's to give an overview of really the sh the vast amount of hormonal systems that are impacted by low energy availability. We're going from energy homeostasis to growth hormone to the thyroid. We have pretty much every bodily hormonal axis major one that is being negatively affected by low energy availability. And therefore, it's not surprising that we see these investment, bone health on performance and on general health, which we will get into in a second. But there's another concept called low carbohydrate availability. And low energy availability is often often occurs kind of in the same in conjunction with low carbohydrate availability. The endocrine responses are very similar and it's also often because energy intake is most easily reduced by simply reducing carbohydrate intake. Um but it's important to know that a low carbohydrate availability has further independent negative effects on bone immunity and iron markers than low energy availability. But now I want to ask you whether just another short poem you think, um whether low energy availability is always detrimental and then you're not on a lot of nose. Um whichever one you vote for. If any of you want to share, why you think or when you think it might not be detrimental, feel free to drop it in the chat or unmute. I'm not sure if you can. Um if not, don't worry, but if you want to share your thoughts, feel free. Ok. So everyone has that has voted, has voted for no. Um And that's true because there is something called adaptable low energy availability and this is when it's periodic and that's when it is likely benign. Um This might be necessary and even unavoidable like in periods of monitored um and mindful manipulation of body composition or in periods of scheduled um intensified training or competition. Um You might have simply extreme increases in energy expenditure and in certain situations you can't necessarily increase energy intake. Um And we'll look at some of these instances in a bit but in periodic or adaptable L ea you have mild and quickly reversible changes in biomarkers of various body systems and these actually can signal adaptive partitioning of energy. So kind of like training the stress you impose on your body through uh weight training or endurance training causes adaptations to that. This transient, low energy availability can also signal certain beneficial actually adaptations in terms of performance um in athletes. So as I said, this might lead to acute health or performance benefits like increasing B2 max or the power to weight ratio. That's important, especially in sports like road cycling or swimming. And as I said, these are typically short term experiences with minimal or no long term health or performance consequences. But the really important thing is, is this is periodic, it's not long term, it's a short term um event that causes acute benefits but that you need to get out of um as soon as possible really to prevent it from becoming chronic low energy availability because that's when you are at risk of reds. I want to stress the fact that low energy availability is not red, it's a risk factor for Reds, but a necessary risk factor for Reds. Reds is always preceded by low energy availability and it is usually long term and or severe low energy availability and low energy availability. Plus excessive exercise must be present for it to fit into the category of relative energy deficiency syndrome in sport, risk factors for reds include sports where high power to weight ratios. Um confer a performance advantage such as road cycling, running, climbing, triathlons, weight category sports like rowing, boxing and bodybuilding, things like that. And then aesthetic sports like um gymnastics ballet and diving. I want to show this because it really underlines how periodic low energy availability can rapidly fall down the spectrum into dramatic low energy availability and breads. Um So in the green triangle, we see optimal energy availability and that usually comes with optimal bone health and human menorrhea. So in the females, humana, um that is just a healthy menstrual cycle. But as energy availability reduces be it with or without disordered eating, bone mineral density starts to decrease as well. And menstrual cycles start to um become disorder and the further you slip down the slope, the closer you get to the red triangle where you have low energy availability, osteoporosis. So um very low bone marrow density and functional hypothalamic amenorrhea. So this is um secondary cause for losing your menstrual cycle here. The cause being um low energy availability and the effects affect, affect every body system. Really, as we talked about earlier, you have um decreased bone health, but you also get mental health issues. You get produced immunity, you get um reduced skeletal muscle growth. Cardiovascular system is impaired metabolism, digestion. Every volley system essentially is negatively impacted by reds and the same goes for performance. You have decreased motivation, decreased strength, decreased endurance, performance, decreased power, decreased recovery. Every aspect that feeds into performance is impaired as well. And that is why we see these curves. So here we're looking at on the X axis training load. So it's intensity and time. And on the y axis wave performance and on the top, you can see the transverse line for full potential and the blue line traces the adaptations of a healthy athlete. So you can see that as training load in load increases, performance increases up to a certain maximum, which is kind of your natural limit. And after that, if you push too hard beyond that performance starts to decrease. And that's because as we touch upon, I think in the very first tutorial, doing too much can be too much and then you are overtrained. Um And that is when performance starts to decrease because again, the the bodily systems are just too stressed, too overwhelmed, they can't recover. Um So that is why performance starts to decrease. Now, what happens with reds is that not only do you not reach your full natural potential, you actually plateau earlier and the decrements in performance that come from training beyond that point are much more rapid and severe than in the healthy athlete. So you're, you're not adapting, your performance adaptations are not as great, they're limited, you can reach the same maximum and you can push as hard. So approaches to recovering from reds usually involve changes to diet and exercise to restore the optimal energy availability. Um but it is usually a multidisciplinary approach because it often involves sports medicine because there's the exercise factor, nutrition because there's the energy intake factor, psychology, if there is an aspect of disordered eating as well as sports science, family and coaching because this happens in the context of physical activity and insufficient nutritional intake. But it's extremely challenging. Um The refuse study published in 2021 did a twelve-month intervention where they had participants increase their energy intake by 20 to 40%. And the positive findings were that 64% improved their menstrual status, increased body mass and body mass percentage and free T three T three being a um thyroid hormone. But there was no change in bone marrow density and the dropout rate was 57% because a 20 to 40% energy intake increase is a lot um especially when you have been on the downward slope. Um so it is extremely difficult, which is why it's really important to raise awareness and to make sure that athletes, sports doctors, nutritionists are all aware of this and can pick up on such cues to make sure that we can intervene before it becomes really difficult to climb the slope back up. But the take home points are that low energy availability can arise from insufficient, insufficient energy intake, excessive exercise activity, thermogenesis or a combination of both transiently may confer health or performance benefits. Bone health is typically the first to be affected by long-term, low energy availability and hormonal dysregulation are characteristic of the it is a risk factor for reds and reds has potentially long term determinable effects on health and performance. So that concludes my tutorial. As usual, I'm gonna stick around for a few minutes now, if anyone has any questions, but if not, thank you for joining me. This was the last tutorial. Um So please do fill out the feedback form again. If you do that, you will get access to the slides and also um you will get a attendance certificate. Um I have been uploading the recordings for all of these tutorials as well on the Met All platform. So do feel free to look back on any ones you've missed or if you wanna refresh your knowledge on any of them. Um You can do that, but yeah, thank you for joining me today.