At the very top end of elite triathlon, we know athletes have to take a no stone unturned approach to their training. Dialling down into every detail to ensure they get every drop of performance out of themselves in training, and on race day.
That highly scientific approach to training is something that the physiologists at the Loughborough University Performance Lab applied to great effect as they worked with short-course triathlon star Cassandre Beaugrand to help her on the road to winning the gold at the Paris 2024 Olympic Games.
The French star might have be racing on home turf in Paris, but she credited her move to Loughborough two years ago in helping her deal with the conditions on Olympic race day. Speaking to the BBC in her post-race interview, she said: “I’d like to say how proud I am that all the group in Loughborough accept me and I want to thank them for pushing me all the way.
“I know I’m very lucky with all the people I have around me. I think it definitely helped me to move two years ago to Loughborough because I’m used to riding in the rain now.”
To find out what Cassandre Beaugrand’s Paris preparations looked like, we headed to Loughborough University to meet with Lucija Petrovic, Physiologist for Loughborough Triathlon Performance Programme, and Rhona Pearce, Physiology Lead, to learn a little more about the physiological science behind performing at the highest level. Plus, we volunteered our own resident amateur triathlete, Jenny Lucas-Hill, to give the testing protocols and a heat chamber session a go herself. Read on to learn more about Cassandre’s road to the Paris Olympics, and watch the video to find out how lab testing can help amateurs to optimise their training based on their individual physiology.
How the team at Loughborough helped Beaugrand prepare for Olympic glory
Cassandre Beaugrand started working with the team at Loughborough University two years before the Paris Olympic Games. And as her physiologist, Lucija Petrovic, explains – the phrase “it takes a village” has never rung more true.
“Cass moved to Loughborough two years ago in preparation for the Paris Olympic Games, and that’s when she came under our support,” say Lucija. “Apart from me as a physiologist, I worked with other interdisciplinary team members. We had another physiologist, a physiotherapist, nutritionist, S&C and lead coach Gavin Smith. We all worked together to come up with a plan of how to support Cass in the two years leading to Paris.”
Understanding the specific demands of the race course in Paris, alongside Cassandre’s individual physiology was a key starting point for the team. “We looked at the race demands when it comes to physiology. I tested her in the lab on the bike and run to understand her physiology and identify areas for improvement.”
“After the Paris Test Event last year, we knew exactly what the race would look like, what the course is, and what we needed to focus on in the last year leading to Paris. Apart from testing, we supported her throughout her training, including swim testing and field testing during training camps and running sessions.”
“We did a lot of heat preparation because Paris was expected to be quite warm. Although the temperatures weren’t extreme, they were warm enough to have a detrimental effect on performance. Therefore, heat acclimation was one of the key things. We were lucky she joined two years before the Paris Olympic Games, which gave us time to test various heat acclimation protocols, understand what works for her, and get to know her well.”
“Going into the last year, we made a year-long plan for her physiology support, including when to do certain testing and heat acclimation blocks to ensure she was prepared to perform at her best.”
Heat acclimation key in going for gold
While being prepared for potentially hot conditions was a vital part of the Paris prep for Beaugrand, the time spent training in the heat also held benefits for her overall performance. Lucija explains further: “I think the biggest impact I personally had was through heat acclimation. Heat acclimation isn’t just about being better in heat; it’s also used as a training stimulus, and we think she responded quite well to it. Considering we had two years, the first year was about preparing her for certain races and learning about her body and how she responds. I knew exactly what needed to be done in the year leading to Paris.
“She was heat acclimatized and also benefited from the training stimulus provided by heat acclimation. This allowed her to perform at a better level. Heat acclimation was one of the biggest pieces of support I provided, scheduling around her training, racing, lifestyle, and everything else. It’s not as simple as just going into a chamber and doing it. It was a long-term plan, working closely with her coach who understood what needed to happen. Together, we came up with a plan for the heat acclimation blocks, which hopefully helped her feel a little bit better than others on the day.”
Along for the ride
After two years of working so intensively with Cassandre to help her prepare for what had to be the biggest race of her life. We were interested to find out what it was like for Lucija to see all the preparation come to such successful fruition. “It was absolutely brilliant. It was a very emotional moment. I’m not going to lie, it was two hours of being very stressed. I don’t think I’ve experienced anything like that.
“It’s always very special to work with all of my athletes. They’re a really nice group and quite successful, and we’re all very proud of them. But her crossing that finish line, especially because she’s French in Paris, is a picture that will always be in my mind. Even if I just helped her a little bit, it was an unbelievable moment.”
How can physiological testing help amateurs to dial in their own training? TRI247 are put to the test
The performance lab at Loughborough is no stranger to triathlon greats – Britain’s Olympic gold medallist Alex Yee also used the facility as a big part of his own preparations. The team also regularly work with amateur triathletes, runners and cyclists to help them reach their own personal goals. For those of us competing in the amateur ranks, we’re tasked with balancing our training with busy work and personal lives. Which means making every hour of training count is vital if we want to have a chance at reaching our potential. Whether that’s going for AG titles or just making it to the finish line within the cut-off time.
The physiological testing available at Loughborough can help you to understand precisely what you need to work on to improve your performance based on your individual physiology. And the results come with training recommendations, so you can make sure you’re not wasting any of your precious training hours on sessions that aren’t going to help you improve. To find out what the testing involves, and the data you can get out of it. We volunteered our own Jenny Lucas-Hill to spend the day being put through her paces by Lucija in the lab. Watch the video below and read on to find out how she got on!
Fuel utilisation and lactate threshold testing
I currently race predominantly over the full Ironman distance. With the bike making up such a huge percentage of the race, this feels like the discipline where I can make the most gains, so I decided to conduct all my testing on the bike rather than the run.
The first test Lucija did with me was a sub-maximal test, which would measure my lactate thresholds and also give us an idea of how efficient my body is at using fat as a fuel. This will help me to set up my training zones so I’m working at the right intensity to get the most out of my sessions. And it will also help me to plan my race nutrition by establishing how much carbohydrate I need to take on board at different power outputs.
What is LT1 AND LT2?
“Training zones are determined based on thresholds: LT1 and LT2 (lactate threshold 1 and lactate threshold 2). LT1 reflects the intensity you can hold over several hours and aligns well with your Ironman pacing. Anything below LT1 is nice, easy riding, and recovery rides. LT2 is the exercise intensity above which there is a sustained increase in blood lactate concentration. This accumulation of lactate is associated with the onset of fatigue, therefore the higher the intensity this occurs at – the better for performance.”
Lucija Petrovic, Physiologist for Loughborough Triathlon Performance Programme
The sub-maximal test was the longest of the day, and involved just shy of an hour on the bike starting off at an easy intensity and increasing by 15 watts every 6 minutes. Lucija took blood samples from my earlobe throughout the test to pinpoint when I reached my first lactate threshold (LT1) and when I hit my second lactate threshold (LT2) – at which point the test would stop. During the test, I also had to wear a mask which measured how much oxygen I was consuming and how much carbon dioxide I was producing. This allowed Lucija to measure what proportion of energy was being provided by carbohydrate or fats to give a Max Fat Oxidation Rate.
VO2 max testing
With the first test done, it was time to spin the legs and get some recovery before the toughest test of the day: the max bike test. This was fairly similar to a ramp test (if you know, you know!) starting at an easy power output and increasing by 5 watts every 20 seconds until I reached the point of failure. Lucija and the team let me pick a playlist (An eclectic mix of 00s pop punk with the odd bit of Metallica thrown in for good measure was my choice for the day) and provided plenty of motivational words of encouragement to keep pushing the power for as long as possible.
The purpose of the test was to determine my VO2 max – that’s a phrase we hear thrown quite a lot when we’re talking about triathlon training. But Lucija explains what it actually means: “VO2 max is the maximum volume of oxygen that you are able to take up and use. This can be used as an indicator of endurance performance potential, although the lactate thresholds are more relevant predictors of your current performance capacity. VO2 max is largely determined by genetics, and in a highly-trained athlete is unlikely to improve much with further training.”
Knowing my VO2 max means I can see how close to my ‘ceiling’ I am with my current thresholds and indicates whether I should focus my training efforts on improving my VO2 max, or raising my lactate thresholds.
The results of the sub-max and max bike tests and how they’ll influence my training
The sub-max bike test showed that I hit LT1 at almost exactly the power and HR I held for my most recent Ironman distance race. Which shows my coach did a good job of estimating what I should target based on my training values! I hit LT1 at 60% of my VO2 max, and LT2 75% of my VO2 max. In my report, Lucija explained that the max attainable values for me are 80% and 90%. What this means is that there’s still plenty of scope for me to improve my thresholds, before I’m limited by my maximal capacity.
I’ve already fed this information back to my coach, and we’ve started focusing more on threshold work in my higher intensity bike sessions. This should help me to be able to hold a higher intensity before I reach that second lactate threshold – which will mean I can ride harder for longer before I reach fatigue.
The fuel utilisation tests showed that being able to use fat as a fuel source is a big area of improvement for me. Once I got to 65% of VO2 max, my capacity to use fat as a fuel dropped off significantly. I currently target 60g/hour of carbohydrates for Ironman distance racing, which has been adequate. But if I want to be able to hold a higher power over the long distance, this carb intake won’t be enough. I either need to improve my body’s capacity to use fat as a fuel at higher intensities, through periodized carbohydrate intake and plenty of aerobic base training. Or I need to start experimenting with increasing my carb intake in training to see if I could tolerate a higher amount in racing next season. I’ve struggled in the past to take on fuel, so that 60g/hr of carbs already feels like a lot for me. Which means I’ll most likely want to focus on improving my fat max – the easy base miles over the winter should give me plenty of opportunity to do this.
Heat tolerance testing
My A race for 2025 is the IRONMAN World Championship in Kona – I just about did enough during the marathon at my last race to get myself a qualification spot. And that means I’ve got some serious heat prep to do. Lucija and the team at Loughborough gave me the opportunity to give their heat chamber a go. Heat acclimation training is something they did a lot of work on with Cassandre Beaugrand ahead of Paris, so I was keen to see exactly what that sort of training entails – and experience what I’m going to be up against in Kona.
The chamber is set up with turbo trainers and treadmills. The team can set the conditions to precisely match different race scenarios – heat, humidity and even altitude can all be manipulated. Lucija set the chamber to 30 degrees Celsius with 84.3% humidity to mimic the typical conditions in Kona. I hopped on the bike and cycled for around 40 minutes at around my target Iron-distance power. Lucija measured my heart rate, my tympanic temperature and performed a sweat test so we could see how well I currently tolerate the heat. And also establish my sweat rate and how much salt I need to be replenishing as part of my hydration strategy.
The results showed that my body coped fairly well in the heat for the first 30 minutes or so, but my heart rate started to increase steadily after that. My sweat sodium levels were fairly low, but my overall sweat rate showed I’m likely to lose about 1.2 litres of fluid per hour in those conditions so I need to plan my hydration accordingly.
Given that I’m definitely not going to get through the 180km bike course in Kona in 30 minutes or less, working on my heat tolerance is going to be really important over the next 11 months so I can hold my target race power without blowing up!
Is physiological testing useful for amateur triathletes?
Getting to train like a PRO for the day was seriously cool – I’m definitely considering booking in another testing day at some point in 2025 to see how my winter and early season training has gone, and to make sure I’ve got my zones set correctly before I get into my main Kona-specific training block a little later in the year.
What I’ve found really useful off the back of the testing is the report Lucija provided me with after my day in the lab. It wasn’t just a case of getting some numbers to look at once and then forget about. There were practical take aways from each test and individualised advice on what I can do in training to get closer to reaching my physiological potential. As someone who is cramming training in around work and other life commitments, this is incredibly valuable to make sure that I’m using the time I have available to train wisely.
I’m never going to be the fastest age-grouper on the course. But what keeps me motivated in triathlon is pushing my limits and finding out what I’m capable of. And the information the testing has given me puts me in a far better place to do that. So regardless of what level you are in your sport of choice, if you love the data and you want to get really specific with your training – I’d definitely recommend a trip to the lab. It’s seriously fascinating stuff.
Visit the Loughborough University website to find out more about physiology assessments and heat training.
