Episode 93 - Blood Tests for Triathletes - What, When & How Often Should You Get Checked for Optimal Performance?

Blood Tests for Triathletes - What, When & How Often Should You Get Checked for Optimal Performance?

What blood tests or biomarkers do you need to test as an active endurance athlete?

You may have seen lots of companies offering blood tests for triathletes lately and it can be hard to know if it’s worth doing or a complete waste of time.

As always, I think it’s important you’re equipped with some knowledge and understanding before doing something like this. So you can make informed decisions and most importantly understand the results and what to do about it.

In this episode I’ll explain:

  • Why do routine blood tests as a triathlete?
  • What things should you test for and why?
  • When should you do blood tests and how frequently?
  • How to interpret your results and how to rectify any abnormalities

Please note: this is not personal medical advice – see a Sports Physician if you’re not sure about you and your specific circumstances.

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BLOOD TEST Guide for Triathletes


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Episode Transcription

Episode 93: Blood Tests for Triathletes - What, When & How Often Should You Get Checked for Optimal Performance?

Taryn Richardson  00:00

Welcome to the Triathlon Nutrition Academy podcast. The show designed to serve you up evidence-based sports nutrition advice from the experts. Hi, I'm your host Taryn, Accredited Practicing Dietitian, Advanced Sports Dietitian and founder of Dietitian Approved. Listen as I break down the latest evidence to give you practical, easy-to-digest strategies to train hard, recover faster and perform at your best. You have so much potential, and I want to help you unlock that with the power of nutrition. Let's get into it.


Hello, and welcome to today's episode. I've been doing lots of podcast interviews lately. It's been so fun chatting to people. And I would love to know, what do you prefer? Do you prefer interviews with other people on the TNA podcast? Or do you prefer me doing solo episodes? Or do you love the mix of both? So can you vote? I've created a poll for you on Spotify - it will show up under the episode’s description. Cast your vote. Tell me what you like. And then I'll plan content based on what it is that most people like to listen to. So today you are stuck with just me sorry, but I have an absolute cracker for you. It's actually one of the questions that came through our Dietitian Approved Crew, Steven H. And I answered it on Coffee and Questions last week. But I really wanted to dive deeper on the podcast where I have a bit more time to chat. And I've also developed a really amazing resource for you. So I'll show you how to get that in a second.


And the question is, "What blood tests should you do as a triathlete or as an active individual that's training for an endurance sport?" And you might have seen lots of ads for things like this lately, too. I've seen lots of companies offering blood tests for athletes. And like Steven was worried about, he's hard to know whether it's just total BS, or if it's something that he's missing out on. So what I'm going to do in today's episode is give you the rundown, particularly from a nutrition perspective - that's obviously my area of expertise. But I think it's really important that you understand what you might need to do and why. And then, most importantly, you need the ability to interpret those results, and know what to do about it. Because otherwise, it's just useless. It's just more data - data for data's sake. And I know, as triathletes, we love data. And we love numbers. And we always want to do everything to the absolute best of our ability. But there's no point doing something like this, if there's no outcome or action as a result. And that might be to do nothing, and then check again, which is totally fine. But if there is something that is needing to be corrected, you need to have the knowledge and skills to be able to correct it.


Now, I do want to preface this episode with a little bit of a disclaimer - this is not personal medical advice. So please see your sports physician, if you're not sure about anything. And if you're not part of the Academy, and you don't have anyone that you can run the results by or pick somebody's brain to ask what this means, then make sure you get somebody with knowledge and skills and expertise in this area so that you can - so you're not getting overwhelmed and confused by stuff that you don't really understand. Or, you know, shameless plug, you could join the Academy when we open in July.


So what I want to cover is what to test and why and, specifically for triathlon, when you should do it and how often you should do it. And then I'm going to give you some normal reference ranges to help you interpret those results. Now, before you hunt down a pen and paper, I've got you covered with a summary of everything in a free download. So make sure you go and grab that dietitianapproved.com/blood-tests-for-triathletes, but you need to put a dash in between each of those words. So blood dash, tests dash, for dash, triathletes. You got it? Maybe if you try googling that it might come up, but we'll see. I probably don't have any SEO on that just yet, because it's new.


So why do you want to go and get blood tests as a triathlete? Primarily, the purpose is prevention. It's a big component of why you would do something like that. We want to catch something early before it turns into a serious illness or injury. Often if somebody has a stress fracture or something goes wrong, we do blood tests then just as part of the medical evaluation, and often find that particular things that are important are actually out of range or low or whatever it is. They're problematic. So we want to, kind of, be on the front foot and be proactive around checking these things to make sure we're catching something early - and we can fix it.


And ultimately, it's for optimal performance, right? As triathletes, we always want to do better, we want to be better. And you can't push hard if say, for example, your iron levels are low. You might be feeling tired and fatigued and rundown that's abnormal from normal training fatigue - you're going to do a blood test, and you're like, "Oh, that's why - my iron levels are actually low". So you're not transporting oxygen around the body effectively, among other things, and that needs to be corrected. Otherwise, you kind of feel like you're pushing shit up hill for a long time.


And the other thing is: How often should you be doing blood tests? And I guess with everything, it depends. I'm going to talk through some of the details for specific tests, but generally speaking, maybe once or twice a year. You might want to do a test in your offseason as a bit of a baseline measure for you so that you can compare it to what happens when you're in peak training load and peak season. And then you want to do it again, in like a really heavy training volume, leading into one of your key events like your A race, or the biggest volume of training. Because a lot of things can't be fixed quickly. We all want a magic pill or potion where it fixes something immediately or yesterday. But say something like iron, our red blood cell turnover is three months, so it's not going to rectify itself in a week or two. So that's why we want to be proactive and catch something early, if you want to perform at your best. But there's also no point just doing random things willy nilly - you know that I really want you to focus on being strategic in your approach - save your time, save your money, and I'll fast track you through what you actually need to do.


So what are we testing? And I'm going to start a little bit more general here. And I'll try and not spend too much time here. I do get excited because I love physiology. But then we'll dive really deep into more triathlon specific things that are very important. So generally speaking, as a medical screen, like if you have a good GP or general practitioner or a sports physician, they're going to check these things, pretty much every time they do your bloods. We want to check that you're in tip top shape, like your major organs, your whole body is functioning effectively and nothing's going awry. So typically, as part of that sort of general blood work, they'll do your LFTs or your liver function tests, or might be called a hepatic panel. And basically, that just gives you information about the state of your liver.


The other thing they'll do is a full blood count, or a complete blood count is another word for it. And it measures the number and status of your blood cells. So things like white cells, which are really important cells, as part of your immune system that fight off infection. Our red blood cells as well. And every red blood cell contains haemoglobin, which is a protein that carries oxygen. So we want to make sure that that is in a good range. Because if that's low, we're anaemic. And that's not going to feel very good when you're trying to exercise. So abnormalities in your full blood count could indicate something like anaemia, or it might also indicate that you've got some physiological changes with altitude exposure. It could also indicate dehydration, that you have a viral infection or some sort of inflammatory condition. So talk to your doctor if something comes back and you have any concerns.


They'll also do your U&Es or urea and electrolytes. And that's just checking the electrolyte levels in your blood. So things like sodium, potassium, and magnesium. And that is really checking that your kidney function is working really well, it's not doing anything strange. If these things are out of balance, then it can lead to abnormal heart rhythms, which is bad, and we don't want that. But typically, if things are working effectively, then that shouldn't be out of range unless maybe you're dehydrated or something. The other thing that they'll do sometimes - I have seen it relatively commonly with active people, though - is your blood glucose levels or a blood sugar level. And it's typically just a random number, which means that you haven't specifically fasted for the test. But it could also be a fasting blood glucose level, particularly if you've got a family history of diabetes, or you've got some metabolic syndrome happening or things like that. But generally, a doctor will just randomly check that and that is kind of a prompt to dive deeper if they need to.


And the final thing that they generally do if you're going in for, like, a health screen, an annual check or something like that, is your cholesterol or your lipid profile. And what you want to get with that is your total cholesterol, plus a breakdown of your good and your bad cholesterol and your triglyceride levels. And those details are actually quite important because, depending on your number, a dietitian can give you specific recommendations to bring them back under control if you need it. Like if your triglycerides are high, which is bad, then there's specific things that you can do to rectify that. The same as if your HDL levels are low. There's other specific nutrition interventions that we can do to help with that. So the details of cholesterol, you need all of the breakdown of all the different types for it to be useful information.


So those tests are a good place to start, just to generally check that you're A OK- your major organs are working properly, nothing is going awry, and you're in tip top shape. You have to be mindful though that exercise can affect some of those results. Like I mentioned, dehydration is a big one. The other thing that happens with your liver function tests your ALT and your AST, they can remain elevated for seven days or more after strenuous exercise. The higher the intensity, and the longer the duration of the exercise workout will result in higher peak levels. And then a levels remain higher for longer. If you're untrained, and by untrained, I mean, you're either very new to the sport and you haven't done a lot of exercise training in your past, or you've been on a break or holiday or that elusive offseason and you're coming back into it, then you'll see larger and longer increases relative to somebody that's more well trained. So just be mindful. That's why I think getting a sports physician in your corner is useful because they understand the intricacies of medicine with sport. And they can highlight that for you rather than worrying that your liver is going to pack it in. It's just because you've done maybe a six hour ride on the weekend or you've just done a race or something like that.


So let's dive into some endurance athlete specific things that you're going to want to check. And I'll give you some details of that. Now your download has all of this. So if you're getting lost, and you're like, "What is Taryn talking about?" go and download that resource and that will make it all nice and clear. So the first one, and one of the most important things to check is iron. Now iron is important for lots of key functions in the body, including oxygen transport, energy metabolism, our brain function, and optimal immune system. Obviously, they're important for us as active people, because they can impact our endurance or aerobic capacity. Also our mood, our perceived fatigue levels and training adaptations in performance - plus your overall health status. Around 15 to 35% of female athletes are deficient in iron and 5 to 11% of male athletes are deficient. There's a few groups that are really high risk of having low iron, and that being female athletes with regular monthly menstrual losses - we lose iron every month. Endurance athletes, because you have greater losses of iron due to training. And vegetarian and vegan athletes. Because if you're relying on plant based sources of iron, they're much harder to absorb than our animal sources of iron - they're less bio-available.


And I guess the other group would be athletes that have a lower energy intake. So maybe you're a smaller athlete, or you're a small eater, and just your overall intake of iron, or your energy budget is on the lower side. So if you fit into any of those groups, you're going to want to prioritise iron - 1.  in your diet, and 2. just monitoring that your levels are nice and optimal for performance. It's something that you want to check once a year. If you have no history of iron deficiency, you've got no symptoms, it's just really just a monitor. If you are a female endurance athlete, or maybe you've had a history of iron depletion, but it was a while ago, like more than two years ago, then you'd probably want to just keep an eye on that twice a year, perhaps in more of a lower training volume versus a higher training volume or definitely before any altitude exposure. And then if you have had a recent history of iron depletion, within the last two years, then it's something you want to monitor quarterly. Like I said, the red blood cell turns over every three months. So we want to get an indication that you can maintain your iron status with whatever it is that you're doing, rather than going into a hole only checking it once a year and then it's a long road to lead your way back out.


Now there are different stages of iron deficiency. So in your download, I'm going to put the numbers for each of the different components of our iron studies and the numbers or the reference ranges that you want to make sure you are within or above. And we do actually have a higher reference range as an athlete, more so than the general population, because we have a higher need for iron. And that's really important to understand. That's why again, I think a sports physician is really useful because they understand those athlete ranges that are different to the general population.


Now, if you're doing your iron studies, you're going to need a full blood count as well, because we need to understand what your haemoglobin is doing. So you might have depleting iron stores (so your ferritin, that's our storage form of iron) but your haemoglobin hasn't been affected yet - which is a good thing. So you're not anaemic. But we can see your iron stores going down, before you get to that point where you have anaemia. So again, prevention, let's see what is going on, so that we can fix it early before it becomes properly problematic.


The next really important thing that you want to check is your Vitamin D. Now Vitamin D is a fat soluble vitamin, and it plays an important role in the homeostasis or another word for homeostasis is like maintenance, I guess, of calcium and phosphorus. Both are really critical for building bones. It's also important for the reduction of inflammation, cell growth, neuromuscular and immune function, glucose metabolism, and we now know that we need Vitamin D, for optimal muscle function. It prevents what's called hypocalcemic tetany, or involuntary contraction of our muscles that leads to cramps and spasms. How cool is that? See, I told you, I get excited about physiology. Now we can get Vitamin D from food - there are a few things like eggs and fatty fish, some mushrooms - but we also convert Vitamin D to its active form with sun exposure. Now, depending on where you live, there might be times of the year where you don't have enough sun exposure to do that conversion. Or maybe the wavelength of light through the depth of winter months is not the right wavelength to do that as well. So it's something that you want to check in the winter and in the summer.


Deficiency in Vitamin D is not a good thing. It increases our risk of bone injuries, which is bad, chronic muscular skeletal pain, and increases your risk of viral respiratory tract infections plus a whole heap of other things. They're just some major ones. Now there is no universally accepted definition of Vitamin D deficiency. However, I'll give you some guidelines in your download for what you're wanting to look for. You want to look for your serum concentration of a particular type of Vitamin D as the main indicator of Vitamin D status. Being mindful, though, that you probably need more, as an athlete, to allow a greater safety net, and to optimise performance. So some, like national sporting bodies that work with athletes, have their own thresholds. We have Australian ones and we have some guidelines around sun exposure in the summer versus the winter, depending on where you live, which state. If you're Australian reach out, and I can give those to you. But I'm not going to put those in the download I don't think - just because it's confusing for everyone that doesn't live in Australia.


It's definitely something to monitor. In summer, when you have more exposure to sunlight, maybe you're wearing less clothing when you're exercising, versus winter, when you're less exposed to light, that wavelength might be different. And the other thing to consider is the colour of your skin. The darker the colour of your skin, the more at risk you are of Vitamin D deficiency as well.


The next thing that I find really important is monitoring your male and female sex hormones. These can be a really clear indicator as a high performing athlete (and by high performing I don't necessarily mean elite, I mean doing all of those hours of training), we want to make sure that your energy availability is optimal. You are not going into the red where you don't have enough energy for your normal bodily functions, let alone training. So monitoring your sex hormones is a good indicator or a red flag that we need to fuel you better because energy availability is a continuum and we don't want to go too far in the red, where we are putting ourselves in low energy availability, our sex hormones are going awry, and we are down in the RED-S category. As a naturally menstruating female, you can check those. If you take any form of oral contraceptive or have an IUD that can affect the results so something to chat to with your doctor. And males, we can definitely check your testosterone levels and see what's going on.


Your sex drive is another good indicator of your energy availability too - if you have a good handle on what's going on there in that space. So sex hormones. But then you need somebody that can interpret those, and then know how to fix that if there's anything wrong in that space. But I think as a high volume, endurance athlete, something to monitor, and very important to make sure that we're not impacting our hormones by training. You will also need to do your thyroid hormones as well and make sure that we're not doing anything there. And if RED-S is a concern, then they'll also add insulin and IGF-1, insulin growth factor one. So just to make sure that our whole body is functioning properly and we're not affecting those things in a negative way.


And finally, another thing to consider, if you are particularly a vegan or vegetarian athlete, is your B12 status. Very useful to monitor if you don't have any, or not a lot of, animal based foods. It's really important for the production of red blood cells, it has many roles, and it's widely distributed in food. And our stores last us for quite a long time. I don't know what it is off the top of my head, but it's in the realms of years. So it's not likely to go from optimal to suddenly really bad - it would be something that you would monitor over time, and just make sure that it is not going out of range.


Now a bonus tip, which isn't bloods, but a good thing to check as an endurance athlete is your bone mineral density. That's something that you could do every two years. And just make sure that the impact of your fuelling and training isn't having a negative effect on your bone mineral density. Again, it's something we want to be more proactive about and preventative. We don't want to get to the point where we have a stress fracture. We do our bone mineral density, realise that you're osteoporotic, because then it is a long road to come back from that as well. Like it can happen. So worth adding that to your list of things just to monitor. Also, depending on your age, the older more masters level athlete (it's a term of endearment), you will be going to want to check your bone mineral density more. But also like we do it with the elites every two years too. Again, just to make sure that their energy availability is good, because it's one of the things that can be negatively impacted if you're not fuelling training for performance.


And that's why I bang on about periodisation all the time - it's so important that you're eating for the work required because you will do damage to your bones when you're young and fit and healthy and doing lots of exercise and you think you're eating really well. But eating for general health or feeling like you eat well is so different to then fuelling training for three sports. It's something we talk about in detail inside the Academy program, because I'm so passionate about setting you up for life, not just for right now. So make sure you grab that download. I've added lots of detail on there. So it's kind of a bit of a summary and cheat sheet so that you are equipped with some knowledge and understanding of the things we're testing and why. And then some athlete specific reference ranges if they're available for that. So that link again is dietitianapproved.com/blood-tests-for-triathletes, blood tests for triathletes. But just with a dash between each of those words. Man, that's so hard to say - I should have made it so much easier.


So just thinking about the practicalities of when you're doing your blood tests as well. Timing can be important. So you generally want to do your tests in the morning. And not after you've done a really hectic heavy training session in the day or few days before. Things will be different if you go and do a blood test right after an Ironman or right after a really hard race. They'll also be different if you do it after a really heavy training block too. So just be mindful that timing is important. You want to do it at the same time of day if you can just for consistency. And as a female, you want to do it at the same time of your menstrual cycle too, if you can. So I hope that's helped give you some broader understanding of what to test and why, specifically for triathlon, when and how often you should do it and then grab your download for some reference ranges and a bit of a cheat sheet to guide you. But most importantly, the interpretation of those results is key. Without it, it's just a waste of time, resources, money, a needle in your arm and data for data sake!


We want to take that information and be able to understand what's going on. And if everything's all good, then smooth sailing. But if it's not, how do you fix that and as quickly as possible? So get a good sports dietitian in your corner. And if you don't have one already, I really recommend a sports physician to do these sorts of annual, biannual or quarterly testing depending on what it is. If you live in Brisbane, Australia, I have some really good connections with sports physicians around me that I've worked with for many years and work with at Triathlon Australia. If you're in other places in the world, ask around or shop around - go and see someone - see if you connect with them. Ask questions, now that you have a bit of knowledge, and make sure you're happy with the answer. You'll find somebody good, and then you'll stick with them for years.


All right team. I hope you enjoyed that solo episode back with me again. Make sure you vote on the poll on Spotify, if you can. I would love to know what you liked listening to. So remember to look for it in the episodes description on Spotify. It'll take you two seconds and I will be guided by the results. Alright. Have a great day.

Taryn Richardson  26:14

Thanks for joining me for this episode of the Triathlon Nutrition Academy podcast. I would love to hear from you. If you have any questions or want to share with me what you've learned, email me at [email protected]. You can also spread the word by leaving me a review and taking a screenshot of you listening to the show. Don't forget to tag me on social media, @dietitian.approved, so I can give you a shout out, too. If you want to learn more about what we do, head to dietitianapproved.com. And if you want to learn more about the Triathlon Nutrition Academy program, head to dietitianapproved.com/academy. Thanks for joining me and I look forward to helping you smashed in the fourth leg - nutrition!  


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