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From Guesswork to Precision: Endurance Coach Explains Why He Uses INSCYD

Meet Tom, an experienced coach specializing in running coaching, triathlon, and marathon training. He shares his coaching philosophy and how he helps athletes with endurance training to achieve peak performance.

From Guesswork to Precision: Endurance Coach Explains Why He Uses INSCYD
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4:22
November 4, 2025

My name is James and I've been using INSCYD for about two years now and it has completely transformed the way I approach coaching. Before INSCYD I was using traditional threshold testing and just looking at power at threshold and making training decisions from that. What INSCYD gave me was the ability to actually understand the underlying physiology.

So not just what the athlete's threshold is but why it is what it is and what the limiting factors are. The first athlete I tested with INSCYD was a competitive age group triathlete who had been stuck at the same performance level for two years despite consistent training. When I looked at his metabolic profile I could see immediately that his VLA max was very high for a long-course triathlete.

It was around 0.6 millimoles per liter per second which is quite high and his fat combustion rate was very low. He was burning almost entirely carbohydrates even at moderate intensities. So the prescription was very clear.

We needed to reduce his VLA max and improve his fat oxidation. We adjusted his training significantly, moved away from high-intensity interval work that was keeping his VLA max elevated, and focused much more on low-intensity aerobic work and some specific sessions targeting fat oxidation. Six months later his VLA max was down to around 0.35 and his fat combustion rate had nearly doubled.

His race performances improved significantly. He went from being stuck to setting personal bests at every distance he raced. That's the power of understanding the actual physiology rather than just the surface metrics.

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I'm Tom. I'm endurance coach in running, cycling, and also triathlon. So, I'm coaching mainly endurance athletes, amateur athletes, and my coaching company name is Level Up endurance coaching. So, to try to assess my athletes, previously I was using regular tests that you can find a little bit everywhere, like the regular 20 minutes power test, or cycling, or even for running, and try to also maybe compare their races, the performance between two races. It was less precise and it took also more time to analyze the data and I was also a bit sometimes unsure in certain cases.

So it was definitely less precise and most more guesswork than working with INSCYD. So I started working with athletes that were a bit more performance oriented. So that really wanted to go to the next level. They wanted to have a bit more data about their performance, and this is a bit where I saw an opportunity for me to work with a tool that enables me to have some objective data about my athletes, and also bring my coaching skills and coaching ability to the next level.

Thanks to something that is more objective, more scientific. So, in terms of using INSCYD, what I like is, when I'm starting out with an athlete, it's that it gives me really quickly a glance of what's the athlete I'm working with, like his phenotype. And based on that, I can craft the training more precisely. And I have this information that is objective. I also like using the INSCYD PPD protocol to create a race strategy that is also more precise, more based on really the physiology of my athletes.

And it's also easier for the athlete to understand the importance of glycogen and race fueling strategy than by showing the numbers, that he has a certain reserve of glycogen, and that at his race pace he's going to use some of that glycogen during the race. Then he understand that by like increasing or by just eating some carbs during the training he will be able to sustain a higher power or a higher speed during his race.

He will just perform better in his race. So that's definitely something that helps also in terms of communication from the coach to the athlete. So usually they are >> >> they're very surprised that with such a quick protocol and a small test you can have so much data and so much information about themselves. So at first they're a bit they're quite surprised and the important things is just to take some times to explain the key metrics of the of the report and also explain them a little bit like how the energy systems are working.

Just very briefly so that they can have the context to understand the indicators better and they are also more sure about where we are going and confidence in the in the training program I'm prescribing to them. So INSCYD basically I would I would say it's a it's a virtual lab that allows you to prescribe and to do some physiological testing with your athletes. So, it's really a tool in your tool set as a as a coach that enables you to have more objective data about your athletes, have a little bit less guess work.

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