We start our podcast channel - Next Level with Mario Schmidt-Wendling

Today, we are starting our podcast series, the Next Level, to explore sports performance with athletes, coaches, sports scientists, and experts. Our purpose is to help advance heat training and heat pacing strategies within the sports community, with the help of those working on the field for several years.

In the first episode of the Next Level series, we discuss with triathlon coach Mario Schmidt-Wendling his approach to heat training and acclimatization protocols using CORE. Mario is an award-winner triathlon coach based in Frankfurt, Germany. He is coaching world-class athletes, including several Iron Man European champions. He defines himself as an old-school coach with an empirical and science-based approach to training.

Mario will introduce the audience to his heat training protocols, a field where he is an expert with more than ten years of experience. He shares his testing protocols and explains the benefits coming from heat acclimatization. We also discuss the differences between heat and altitude as training tools, how para-athletes regulate body temperature, and the challenges ahead. Enjoy!

Christopher Jones: This is the Next Level, where we explore sports performance with athletes, coaches, sports scientists, and experts.

I’m your host Christopher Jones from CoreBodyTemp Monitoring.

This week on the Next Level, we welcome Mario Schmidt-Wendling from SISU Training. He’s based in Frankfurt in Germany. Welcome, Mario.

Mario Schmidt: Welcome. Hi!

Christopher Jones: Outside, here in Germany – I’m also located in Germany – we have freezing, cold weather. They are scraping ice off the street so that the cars can travel, and it’s cold where you are in Frankfurt as well.

Mario Schmidt: Yes, it’s some kind of absurd that we are talking about heat and heat adaptation, and so on, it’s so cold outside, it’s kind of weird. But summer, hopefully, will come up in the next few weeks, months. There’s still some potential for heat adaptation and its topics.

Christopher Jones: That’s right. And it’s all about indoor training at the moment. But let’s find out a little bit about you, Mario. You have some professional experience as a sports person. So, what is your history in sports?

Mario Schmidt: I did my first triathlon in 1990, so, it’s a pretty long time. And with a small episode as a cyclist, from 1980 to 2006 in the beginning, and a couple of years as a professional on the continental level. And afterwards, deciding to go back to triathlon. So, it’s over 30 years in endurance sports. And I’m still trying to be active. It’s getting harder because I’ve got four children at home and a company I’m running, so there isn’t much time for sports anymore - sadly.

Christopher Jones: With your company, your business SISU training, when did this start and what type of sports people do you look after?

Mario Schmidt: I studied Sports Science in Frankfurt, and when I quit being a cycling pro, I started doing training plans for triathletes at the end of 2004. And from then on, I really worked with triathletes, and especially with long distance athletes. So, no beginners – primary, experienced athletes - no really beginners. Because in my opinion, beginners should go to triathlon clubs in Germany. Because in German Triathlon Association, they are doing a great job educating the trainers and beginners – they learn everything they need to know in the beginning at the triathlon clubs in Germany.

Christopher Jones: With regard to your athletes, do you find that they have a particular focus when they come to you? Do you have, let’s say, a reputation with certain training methods?

Mario Schmidt: No, I describe myself as an old-school coach. I’ve got that science background, but more on the empiric side of sports, and really looking for some real-word sports scenario applications, whatever, meaning, that’s a mixture of science, and experience, and observing. And it’s not only science, and it’s not only empiric observations, or whatever, it’s definitely the mixture. I try to educate myself by reading a lot of scientific newspapers, almost every day, but, on the other hand, talking with athletes or reading their comments in the training diary – it’s on the same importance level.

Christopher Jones: Mario is one of an early adopters of the CoreBodyTemp Monitoring technology, and he’s had a chance to be able to use this with athletes. One of the things that I’ve been really fascinated with is some testing, which Mario has done. He’s provided a test document, which will be available in this content when we publish this. And the listeners will be able to find the link to this in the description. So, this is a document titled, SISU Training: Triathlon Training Optimized For You. It is in German language but relatively easy to understand. Just to describe this for the listeners. We have, let’s say, an Excel table type of format. We have, I understand, four test candidates, so, four athletes who are anonymous. And looking through this Excel table, it is a lot of testing, using temperature and also other attributes, such as, we have a column called The Critical Core Temperature, which is, I understand, a target limit for each athlete. So, for example, for athlete A we have 38.7ºC, for athlete B 38.5ºC, athlete C 38.7ºC, and athlete D 38.4ºC. So, just starting with like a target temperature, or a critical Core Body Temperature, what does this actually mean, and how do you decide what number suits which person?

Mario Schmidt: Every season, I'm looking for chances to improve the performances of the athletes. Since 10 years, I'm looking for solutions about heat adaptation because so many athletes working – sorry for the word - their asses off training and struggling with heat conditions in the main races. So, I was always looking for some solutions or some ways to improve their performances, especially in the heat combined with the high humidity, like in Ironman Kona. So, I started doing some stuff with some sweat testing, and this is one pillar of my - I call it “beat the heat” concept, and the other one is “core”. And with that CoreBodyTemp, with its sensor, I'm able to observe or to measure the critical core temperature. These differences in the core temperature between these four athletes in that spreadsheet, they are coming out of the heat ramp test, which is already published on your website on Core Body Temperature. So, we did that heat ramp test to get an idea of what the critical, individual core temperature of the athlete is.

Christopher Jones: This would be, for example, a target temperature for an athlete, you want to be at this level in terms of driving your plasma levels. This is not a top limit, which is, let's say, a limit in which an athlete would suffer heat stress or a target limit for their performance?

Mario Schmidt: Exactly.

Christopher Jones:  Okay. we've also documented, within this excel spreadsheet, the room temperature. We have a range of room temperatures. I can see on a glance, starting from about 17ºC, all the way through to 26ºC room temperature. We have the temperature with the athletes started, whether or not the athletes had coffee. The intensity of the workout, whether or not they had cooling, such as a fan, and the level of cooling, how much fluid intake the athlete had, the length of the training session until they reach what is known as our target or our critical core body temperature. So, with regard to this duration, some of the training workout had the athlete actually not reaching the target of, for example, 38.7ºC as a target. The target was not limited, but you might see the fan was on. We have a column called RPE? What is this RPE column?

Mario Schmidt: It's a Rate of Perceived Exertion. That means they have to write down their real subjective feeling during the session, how hard is the session, how does it feel. And it's a little bit connected to the Borg Scale, but only the numbers from 1 to 10. So, 1 is easy and 10 is almost dying. And as you can see in that spreadsheet, some athletes really suffered from that heat stress, some typed in number 9. It's really, really hard. But this varies from athlete to athlete. It’s same for pain. For some athletes, pain doesn’t exist, and for others, they really suffer right from the beginning on. This is just to get an idea of how the athletes respond to heat, or how they react to heat, or how they really feel. And maybe to get an idea if the athlete is a candidate for a potential heat adaptation, if he's benefiting from heat adaptation – this was the idea, to get this RPE.

Christopher Jones: The final column after the RPE is the Sweat Rate, which, as you have suggested is measured based on weighing an athlete before and after the session.

Mario Schmidt: Exactly. It's not only the body weight, it's plus weighing the fluid that they took in. So, you get an idea of how many sweat they produced or they lost in that period of time, especially in an hour. If you know the athlete's sweat sodium concentration, you get an idea of how much work the body has to deliver for the cooling system. I mean, the humans are exceptional at thermoregulation and cooling due to evaporative heat loss through sweat. This is maybe one point why our species is superior, because we can definitely maintain a steady core temperature to a certain point of performance.

Christopher Jones: That's right. As an athlete, when working, our body naturally sweats to aid our cooling. Then, we get the cooling effect from wind. So, it's fascinating also looking at the Ventilator Column, or the column with the cooling, and seeing that we have a cooling from 0, which is no cooling, to 3, which would be a maximum cooling effect.

But there's one athlete, candidate A, who also has the perceived effort, even with high cooling - this would be a few columns down in dark blue - a high effort of 8 out of 10. But also, the fans on maximum. Even with the fans on maximum, they were still perhaps in a zone where it was quite excruciating.

Mario Schmidt: Yeah, it depends on the performance or the intensity level. So, SB, the column on the left side, is in German “Spitze Bereich”, and it’s maybe in English terms “zone 5 level” - that's a really hard all-out effort, and with a lot of heat production. He suffered during that session, even with having the fan on a high level. It shows that it's not only a matter of cooling outside, it's a connection between cooling outside and the intensity level.

Christopher Jones: That's right. The intensity is one thing that we've seen with core when we have a look at athletes, for example, the data from the Tour de France or the Giro d'Italia. We see that with the high intensity of riding uphill, even if the temperatures are quite low, then, that's where the core body temperature rises. There was a stage early on, in the 2020 Giro d'Italia, where the outside temperatures were getting up to about 0ºC. Quite cool - 0ºC. But because of the high intensity levels, we could see that the athletes still had a really, really high core body temperature. I guess it'd still be fair to say that cooling still has a positive effect or a good effect, but the intensity is probably the number one, the amount of effort you're putting in.

Mario Schmidt: Exactly. This spreadsheet, it’s a way of collecting some data. I tried to observe some conclusions or some patterns to see if it has an influence if you took in some pre-ride caffeine, or is there a connection between intensity and the level of cooling, with a Wahoo headwind in this case. And this spreadsheet is just getting a first insight or a first idea of how these different aspects affect the increase of the core body temperature.

Christopher Jones: Looking at this chart, I see it’s a fantastic collection of data, but it's quite difficult to see some really exact patterns, for example the room temperatures between the athletes, rather than being stable, they do vary. But I think that the purpose is to try and identify are there any aspects, which we can see, which have an obvious impact, for example, even the coffee before the ride, is there any obvious correlation. And I think this is a first testing ground, which will probably give way to a second test. Are there any specific things which you would add to a second test, or want to find out, or anything from this test, which you would then remove?

Mario Schmidt: Yeah, for sure. This first test was just - as I already said - to collect some first data. The second step would be having different test protocols. It means having a fixed room temperature, or a fixed intensity in terms of what’s on the bike, and having a fixed ventilation level with the Wahoo headman. So, we have to get a chance to compare the data with a standardized test protocol maybe. This would be the next step.

Christopher Jones: And you mentioned previously, with regard to the sweat and the sodium, would you just be able to describe how you understand sodium? And I have a follow-up question shortly, with regard to how this impacts your testing, but how does sodium work for you, and what do you prescribe for your athletes?

Mario Schmidt: The sweat sodium concentration, we can say it's kind of genetically determined in the human body, and it varies between 230 and 2300mg per liter of sweat, which shows that there is no rule of thumb possible for a sodium intake in a competition maybe. The sodium is important for getting the fluids from the GI system back to the blood system. It’s like a door opener, and this is the main aspect for getting some sodium into the nutrition strategy in races. The other one is there is a transporter, it's called the SGLT1, sodium-glucose linked transporter 1, which is the same mechanism to get carbs from the stomach into the blood system. It shows if you don't have enough sodium in your drink, or in your gel, or in your bar, the amount of carbs passing through the wall of the stomach into the blood system isn't sufficient. So, this is definitely connected, sodium and carbs are definitely connected. And if you want to maintain your blood plasma level, because blood plasma is the fluid which is coming onto your skin, and with evaporation it offers the cooling. So, without sodium, your blood plasma level is getting low, and the viscosity of the blood is raising, so the heart has to push more because blood is getting thicker, and it doesn't flow properly through the veins. You have to maintain a sodium level to help the body maintain the blood plasma level. And blood plasma is important because without blood plasma there is no sweating possible. And sweating is the way for humans to dissipate heat out of the body.

Christopher Jones: So, when we talk about blood plasma from the core body temperature perspective, we're looking at - in training - to increase the blood plasma, which, in turn, increases the entire blood volume. So, you're working more efficiently for delivering oxygen to your muscles. With regard to - during a competition, you need to maintain your sodium levels, is there an interplay, or is there a connection between the core body temperature understanding of blood plasma and the way that you would, let's say, top it up with sodium?

Mario Schmidt: It's a good question. I mean, I’m not a researcher in the topic, I'm still a coach, and looking for some ways to improve the performances. If there's a connection between a certain core temperature and sodium concentration, I have to observe, I have to think about it. And I'm just in the beginning of connecting these two systems for beating the heat or helping the athletes beating the heat. I think you can't separate these two aspects, you have to connect them, because there's definitely a connection between them. But how and when, I’m not sure how to connect them right now.

Christopher Jones: Well, that looks like you've got some work to do to understand how this works for you and for your athletes. I look forward to hearing more about this, but I think that what we'll do is, we'll move on to another topic. I know that you've had experience with para-athletes. Would you just be able to describe your experience, and then, would like to move into what core body temperature means for para-athletes?

Mario Schmidt: I was a national head coach of the German para-triathletes in 2018. And there was a world cup race, World Para-triathlon Series race in Iseo, in northern Italy. And it was pretty, pretty hot on that day. And there were some researchers, some scientists from the university in Loughborough, in UK, and they served some heat pills, and wanted to get an idea of how para-triathletes have problems with heat dissipation. And when I was looking at the study, I was thinking that there was a big difference. Because if an athlete is sitting in a wheelchair, or having a prosthetic, he’s got a bigger surface connected to a different material, maybe carbon, or steel, or whatever. So, convection and conduction, two influence factors of increasing heat or losing heat out of the body are different to an athlete who is riding a bike, sitting only on a saddle, and having connection with his hands on the handlebars. There's a bigger connection between the machine, or the wheelchair in this case, with a body. I think this is definitely a bigger problem, because handicapped athletes, they have a bigger potential for heat stress, or heat strokes, or heat illness, because they have got more chances to lose that heat. This is what I was observing.

Christopher Jones: It's more limited the heat dissipation. But also, with regard to the actual body cooling, I understand that there can be a lot of differences with a para-athlete, compared to a regular athlete, in which they may not be able to rely on the same thermoregulation.


Mario Schmidt:  Yeah. If you work with para-athletes, there are no two para-athletes who are identical. They don't have the same handicap, and they don't have the same equipment solutions and training solutions – you have to treat them very, very individually. This is the difference between working with para-athletes and non-handicapped athletes. Because non-handicapped athletes, if you know their physiological paramedics, it's no problem to treat them the same way – oh, my English is getting worse. Sorry! But with para-athletes it's difficult because there are no two para-athletes who are identical.

Christopher Jones: It would be fair to say, there's a lot of work and research that can be done with para-athletes, but a challenge remains that, because they have individual requirements, that it's very difficult to generalize. Whereas with like an able-bodied cyclist or triathlete, it might be easy to do a test, make a rule with a bunch of athletes and then say, “This is a rule or a guideline which would suit many, many others.” Whereas with para-athletes, you have to look at each individual and work out how - exactly as you mentioned - how their equipment works, how they use their own thermoregulation, what limit time, what their requirements are.

Mario Schmidt:  Exactly. If somebody is using an arm prosthetics, the surface between

the skin and the material isn't that large as for somebody sitting in a wheelchair. He's got a bigger surface connected between body and material. So, there's no rule of thumb for working with para-athletes, it's definitely not.

Christopher Jones: And sweating was also one of the things which I'm aware of whereas some para-athletes will sweat differently, which means, if they, for example, don't have the use of certain parts of their body, and they don't cool through that body area or the skin surface area, but without the sweat, they can't cool though. That means that the demands for their cooling are much higher.

Mario Schmidt: Exactly. That's a big, big problem. I was there with an athlete who lost accidentally his leg, right underneath his knee, and he was wearing a prosthetics after that race. He allowed me to touch his skin, and the skin temperature was very high. You can definitely feel the difference between that area in the prosthetics compared to the non-handicapped areas on non-handicapped leg. For me, it was an eye-opener that you definitely have to be aware of it, that para-triathletes have a different way of thermoregulation than non-handicapped athletes.

Christopher Jones: The way that we could help para-athletes essentially improve - we're talking about improving performance, sporting performance - I understand training, and obviously training the body, so moving the body within a heat stress type of zone so that their body can adapt, is probably one method. I can also imagine that during competition that with the right equipment, materials, clothing, then you can also help cooling strategies. Would that be a fair overview? Or would you see some other areas where the athletes can be supported to essentially improve their thermoregulation and performance?

Mario Schmidt: I think that federations did a good job with the Tokyo Olympics weather conditions, with a big heat stress in terms of WetBulb Globe Temperature (WBGT), meaning temperature, humidity, radiation, wind speed, and so on. And every single federation knows that there will be very difficult weather conditions in Tokyo. So, they created some strategies for the athletes, on the handicapped and the non-handicapped side, to get a little bit more heat adapted. I know that some federations in the para-triathlon world, they are working with some cooling materials in those connection areas between man and machine. So, they definitely think about it. I mean, it's Olympic sport, so the governments offer some money for science and for the federations to get that more into the mind of the athletes and the coaches. So, this is definitely a good way. And it's always, in sport, that the high performance sector or high performance area will get the information from the science, and two, three, four years later, in the age group sports or amateur sports, they will get the profits as well.

Christopher Jones: You're building a foundation of knowledge already with your initial training and testing, which also you're publishing on your own Instagram I understand, but, of course, for listeners then, this test document will be available for you to have a look at and to explore yourself. I'm sure, Mario, that you'd welcome any input from people who have other ideas on this. And certainly, with the whole ideas of training and how thermoregulation works, there are sometimes competing theories out there and competing ideas, but what is your essentially next step with regard to taking this further? Is core body temperature, is it one of many different facets you're looking towards? Or, are you concentrating on a few aspects at the moment as you develop further?

Mario Schmidt: I mean, this sweat sodium thing - I'm totally fine with it. I’m at 10 years of garage science by myself, and I’ve made some conclusions for myself and especially working with Precision Iteration from UK, they offered me their experiences. So, this is one pillar. The other one is heat adaptation. Now, I'm looking for the next test protocol step to get some ideas of how I can implement some heat adaptation blocks in the ramp before an Ironman race. And the third pillar would be some cooling strategies in the race. I’ve already prescribed using some wrist coolers, or neck coolers, or cooling caps, some certain textiles with the chance of cooling the core body temperature a little bit down. Maybe two years ago, at the Ironman, Kona, everybody was running with the Omius headband. And something like this would be the third pillar. And for me, sweat sodium concentration testing and cooling clothing are safe. And the middle pillar would be working on a protocol for heat adaptation training, and how to get the best out of it. I had some experiences with heat adaptation training, but it was only just doing it. Before Kona, I prescribed some heat adaptation trainings, with no background science. They had to wear three-layer or four-layer jerseys, and do some sessions on the turbo trainer. I prescribed some saunas, some hot baths, but nothing really standardized or with a good test protocol - it was just doing it. I want to get a little bit more into that topic. I want to get a little bit more into safe test protocols to see “If you do this, the result is that.” This is maybe my work for the next few weeks, months, years - I don't know how long it would take, but this is definitely a big topic. I see the potential of getting adapted to heat training has for me - the bigger potential than going to an altitude training camp. Because I had some bad experiences with altitude training, some responders, some non-responders. And it's a matter of time, a matter of money, a matter of logistics, and not every athlete is able to go to the altitude training. Because it's expensive, and it costs a lot of time. So, I was looking for some way of improving the performance besides altitude training. And I see a big potential in heat adaptation training.

Christopher Jones: This is really interesting that with altitude training I've also heard the same, also from very renowned sports scientists, that not everyone will respond in the same way although altitude training and heat adaption, they work slightly differently, from a physiological aspect. They do trigger slightly different responses, which is true, although the general understanding is that the response rate for heat training or heat adaptation type training is essentially a much higher response. Certainly with the Olympics and with Kona, with these as primary goals, then it is a no-brainer. This is something which an athlete should be doing to give themselves a chance. Also, arguably, with a better performance chance with the heat training or heat adaptation than with altitude training because of the hot weather conditions are expected over in Tokyo. So, yeah, this is really interesting to follow, perhaps also another aspect is with the heat training. Although there is some knowledge out there, it has not been as well established because it has been a little bit difficult to measure up to now. I feel that the knowledge will start to grow. So, we are at the earlier stages at the moment to explore and understand how it works, and then to define our practices or our theories about how to implement this best.

Mario Schmidt: Yep. For sure. You can definitely see heat as a training tool. Because when you exercise in the heat, you will have slightly increased lactate levels. And as a result, you will maybe have the potential of more signaling, so a higher response to that. And, yeah, you have these heat shock proteins a little bit higher. So, there's a potential for more mitochondria. This could be an aspect as well. Or, if you train in hotter climates, your stress hormones will be slightly elevated. So, this could lead as well to a bigger training response. So, it's not only for getting adapted to races in hot or humid conditions. I think, if you use it as a training tool, you will definitely benefit from that training tool, even for racing in moderate climates. This is definitely a way of thinking that you can use it, even if you're racing in 18ºC, or something like that.


Christopher Jones: That's right. I think that the heat acclimation or heat adaptation for racing in the hot weather conditions, such as in Kona, or with the pending Tokyo Olympics, that is among sports people a relatively known concept, but the idea of heat training to get essentially the performance benefit from this heat or this heat stress but actually for competing within normal or cooler weather - that's a relatively new concept but arguably more appropriate for more competitions or for more people. Because the number of hot weather competitions is much more limited than the number of, let's say normal, or cooler weather competition. So, arguably, the heat training is more applicable for a broader number of athletes.

Mario Schmidt: Yeah, but thanks to global warming we have in the middle Europe area where I live, in the last few years we had Ironman, Frankfurt editions with temperatures around 40ºC. So, it's not only Kona. And in 2019, Frankfurt was hotter than Kona. So, it's not only Kona or the Tokyo Olympics, in the summer sports in Europe, you have to cope with hot conditions. It's not only reduced to certain areas in the world, it's a global problem or a global challenge.

Christopher Jones: Which is a complete new discussion as well, but it looks like it's coming closer towards us. I have a final question for you, Mario. This is a hypothetical -you are competing in the Kona triathlon, Kona Ironman, and you're coming towards the finish line, you're about to win, but you notice your core body temperature is soaring. What do you do? Do you slow down? Or do you have some cooling strategies which you could implement to bring yourself across the finish line first?

Mario Schmidt: I would switch off my device and go as hard as I could. Now, it depends on the kilometer markers. Maybe, if it's early in the race, you really have to focus on avoiding high critical temperature. But if you're running maybe at the 30, 35, 38-kilometer mark, you have to push through that, I think. It’s a good question, because when would you decide to ignore the core body temperature? If it's too early or if it's too late - I don't know. That's a good question.

Christopher Jones: It's a question without a very good answer. I think it's a very tough question. But, look, thank you very much for taking part, Mario, in the Next Level, the discussion where we learn more about sports performance, and also about thermoregulation, and core body temperature. I appreciate you taking the time and also going through some of this data, especially with the chart that you've shared and your really intensive testing. So, we look forward to seeing what comes next, and trying to look through the results. If you'd like to find out more about Mario and his coaching, you could visit sisu-training.de. You can find out more about Mario and his training office. So, thank you very much, Mario, for joining me.

Mario Schmidt: Thanks for having me. Sorry for my bad English today. I'm a little bit tired. I'm better in German, I think.

Christopher Jones: Yeah, next time, it’ll be in German, and I'll be the one apologizing for my German. So, thank you again, Mario.