Is your FTP lying to you? Why lactate profiling could be the future of physiological testing for cyclists

There's almost unanimous agreement that using training zones is the most effective way to progress as a cyclist, but how can you be sure your zones are correct? For years I used a functional threshold power (FTP) test to determine mine, only to find out during a lactate profiling session that they were some way out... but what exactly  is lactate profiling? 

> This is why you’re not a Tour de France racer

Last year we subjected Liam to a load of tests to find out why he wasn’t (and to the best of my knowledge, still isn’t) good enough to be in the Tour de France. Well, blood lactate profiling promises to be the gold standard of physiological testing that's currently trickling down from the pros to the masses, and takes things one step further. This test allows riders to map their strengths and weaknesses as a cyclist and pinpoint their current fitness using science. Other, more basic tests could be influenced by caffeine, fatigue, or simply how well practised at it you are. 

Cardiff-based fitness test experts Synergy Performance helped us run through how a lactate profiling test works, what they can tell us and why this isn’t going to be the last time you hear lactate testing mentioned in the world of cycling. Oh, and we'll also be looking at my numbers to see just how much they differed from my predicted FTP, and how far I've got to go to beat a pro...

Is lactate profiling better than an FTP Test?

Your FTP, or functional threshold power, is the highest possible power you can hold for around an hour. It's by far the most popular metric for determining training zones, and can be tested relatively easily so long as you have a power meter.

There are many different ways of testing FTP. Some coaches recommend a 12-minute test, and others a five-minute test after some intervals; but the most common are either a ramp test to failure or a 20-minute test.

Since I began training, and in an attempt to progress rather than just spinning for fun, I've always used the 20-minute test. This is where you ride full gas for (you guessed it) 20 minutes, and then multiply your average power by 0.95.

From this you can use software such as TrainingPeaks to determine your training zones. So, how can a lactate profiling test be any better?

Well, the easiest way to explain is by pointing out some of the flaws of the age-old FTP test. For example, do you do it fatigued or fresh? We all want to produce the biggest numbers possible, but are we just artificially bumping up the zones and shooting ourselves in the foot for harder sessions if the test is done totally fresh?

Then there are other external factors such as stress from work, what you've eaten in the run-up, caffeine consumption, hydration, and simply how hard you're willing to work on one particular day. Obviously, the best thing to do is to keep your testing as consistent as possible, but that's not always easy when some factors such as the weather and season we're in are well out of our hands.

One final issue with FTP tests is that you can train yourself to be better at them! When I started cycling and performing FTP tests, my pacing was horrific. I'd go out too hard and by halfway through the test, would be chewing my stem and slumped over the bars. Obviously the training I've done since has helped to boost my FTP, but how much of that figure is simply because my pacing has improved? 

> How training zones can help you get your greatest cycling fitness gains

Luke Craddock of Synergy Performance highlighted that traditional power testing only shows if you've got better at riding a set duration, rather than whether you've improved across the board. Craddock explains that with lactate testing, "we are looking at improvements at a cellular level and therefore can see a shift within your physiology.

"That might be key for your event, and sometimes this occurs without any change or even a decrease over these generic 12 or 20-minute power test numbers, highlighting the importance of having a profile."

Power testing will always be limited by the fact that your training zones are based on a fixed percentage of your FTP, but not everyone is built the same. By removing this assumption it's possible to pinpoint training zones that are unique to a particular rider.

Craddock adds: "If I lactate test five riders with an FTP of 300 watts, they would all produce a different set of training zones based on how they fuel performance. This is why for a time-crunched athlete, lactate profiling is so key."

Is lactate testing a new idea?

It's no wonder, then, that lactate testing has been used in the pro peloton for 10-15 years, with Team Sky putting it to particularly good effect throughout most of the 2010s. It's clear that lactate profiling is now commonplace throughout the World Tour peloton, with no one a firmer believer than Iñigo San Millán, Tadej Pogacar's coach. 

Craddock says: "A common misconception is how people assume lactate testing is only for pros. I am a believer that the more time-crunched you are, the more fundamental a profile is."

You might expect someone who specialises in lactate dynamics to say that; but the undeniable fact is that if you want to progress, and only have limited time to do it in, then each turn of the cranks has to count.

What even is lactate?

> How to improve your power-to-weight ratio — lose weight sustainably and get faster cycling up hills

Simply put, lactate is produced when carbohydrates (in the form of glycogen or glucose) are broken down anaerobically (without oxygen) to produce energy, in a process called ‘glycolysis’.

Lactate and lactic acid aren't the same! 

"A common misconception is that lactate is bad," says Craddock. 

"Actually lactate, once transported back to the slow twitch muscle fibres, is turned back into ATP [a form of energy]. Understanding and profiling the concentration is key to determining how your body is fuelling exercise.

"Lactate has to be transported by the blood from fast twitch to slow twitch muscle fibres where it can be converted to energy. That's why a large part of the tests focusses on an individual's ability to clear/shuttle lactate."

He went on to explain that it's this shuttling that makes the best of the best so good, and it's something that traditional power testing could never tell you.

What's being tested (and what it all means)

> Can you get fit by cramming all of your riding into the weekend?

The testing is broken down into two tests designed to collect lactate readings when riding both aerobically and anaerobically, as well as peak and lactate clearance rates.

Using these markers at set intensities, an insight into how your energy systems are fuelling your performance can be built. In Craddock's words, this gives you "an understanding of where you currently are within your sporting journey, which is fundamental before you can plan a road map for achieving a goal."

• Aerobic threshold (LT1)

The first lactate threshold, often referred to as LT1 or 'the aerobic threshold', is the lowest intensity at which there is a sustained increase in blood lactate concentration above resting values. That's the boundary between zone 1 and zone 2 to me and you. You should then, in theory, be able to ride at this intensity for a really long time. 

• FatMax power range

FatMax is kind of what it sounds like: the maximum amount of fat that an athlete can 'burn' per hour, and often considered to be the very top end of Zone 2. Because you're burning primarily fat and not carbohydrates, very little lactate is produced and hence fatigue from this training is low. This is why coaches often prescribe upper-end zone 2 training.

• Maximal Lactate Steady state (MLSS) (LT2)

Your second lactate threshold, LT2, is ​the intensity at which there's a rapid increase in blood lactate, indicating the point at which lactate production exceeds the ability to clear it. It is this LT2 value which is very closely related to the FTP figure.

• Anaerobic capacity/VLamax

VLa max tells us our maximum lactate production rate, and therefore the capability of our anaerobic system. VLa max is closely linked with VO2 max, and can tell us how punchy or endurance-focussed a rider is.

• Lactate clearance/shuttling ability

The body's capability to lower lactate concentrations in the blood is important in any endurance sport that requires efforts that aren't always steady-state. A poor lactate clearance ability could limit your physiological strengths within a race situation, where bursts of effort followed by quick recoveries may be required.

In simple terms, lactate profiling will give us an understanding of how my body reacts to (and recovers from) different efforts, whether they're long, short, hard or easy when out on the bike.

The tests

The profiling is broken down into two main tests. The first is to isolate the aerobic system, and the second to isolate the anaerobic system.

Test 1

The first test is similar to a ramp test, but instead of going up in predetermined steps, Craddock would review each lactate reading taken to determine the power that I should ride at next. This enabled him to ensure that a threshold wasn't missed, and pinpoint them with the desired accuracy.

The test was complete once Craddock was satisfied that my blood lactate had increased above my LT2 (Similar to FTP). This meant that although the test didn't feel easy, it did feel easier to complete than a traditional FTP test, where I'd have had to ride at above threshold for a significant amount of time.

Craddock added that this means a lactate profiling session can be achieved without being detrimental to other training sessions during the week.

Test 2

The second part of the test was a super short intense effort followed by a period of sitting, again with my lactate measured and tracked at set increments. This test helped to build an understanding of how I use glycogen as an energy source, and also my ability to clear lactate in an isolated state. 

It's worth mentioning that climbing off the bike immediately after a sprint is a bizarre feeling. Craddock explained that this was necessary, as even easy pedalling would improve my lactate clearance rates.

The results

> How to get the most from your limited training time

LT1

LT1, as we discussed earlier, is the point at which your body stops using fats as its primary fuel source. I was happy to find that this was a strength of mine! The fact that my body is effective at oxidising fats is probably why I can hold my own on long group rides with riders of a higher calibre than me. In Grand Tours it's this aerobic system that is arguably most important, so that riders don't ramp their lactate just sat in the bunch.

Jamie: 250 watts

UK elite rider: 275 watts

WorldTour pro: 300-320 watts +

FatMax

FatMax is the wattage that I need to sit at to burn the highest quantity of fat. Personally I'm not looking to lose weight, but this will still be an important zone to train in as it's the hardest I can ride without fatiguing my muscles too much.

Jamie: 230-250 watts

UK elite rider: 260-280 watts

WorldTour pro: 280-320 watts +

LT2

LT2 is where the lactate rapidly increases, and proved to be much lower than I expected. For my prior FTP test, I'd ridden at 350w for 20 minutes, giving me a calculated FTP of 332. However, the lactate testing pinpointed my LT2 at 300 watts, some 10% lower. This obviously has a huge impact on my training zones, and Craddock said that this is more common than you might think among experienced cyclists that are well-practised at performing FTP tests.

Jamie: 300 watts

UK elite rider: 360 watts

WorldTour oro: 380-400w +

VLamax

VLaMax typically ranges from around 0.2mmol/L/sec to 0.8mmol/L/sec. With more endurance riders being towards the lower end, and more punchy/sprinter types being towards the top end. My result shows that I am not a punchy rider at all, and if I want to do better in races or competitive group rides, then this is an area to work on.

Jamie: 0.14 (mmol/L/sec)

UK elite rider: 0.44 (mmol/L/sec)

WorldTour pro: Climber 0.2-0.5/Sprinter 0.5-0.8 (mmol/L/sec)

Lactate clearance

Finally the all-important lactate clearance rates, and the area that riders such as Pogacar and Roglic shine. Your ability to process and clear lactate is important for improving both aerobic and anaerobic capabilities, and up until now has been an overlooked metric within endurance sports due to difficulty measuring it using traditional power duration curve methods.

Jamie: 0.28 (mmol/L/min)

UK elite rider: 0.38 (mmol/L/min)

WorldTour pro: 0.73 (mmoll/L/min)

*data subject to the testing protocol used and are based upon a 70kg rider

It looks as though I have some work to do before you see me in a Grand Tour then! A Tour de France Pro could quite easily drop me before even beginning to burn carbs, or riding at a pace that might cause them some distress. My VLamax also puts me firmly on the endurance end of the spectrum, so even if I did somehow manage to make it to the end of a race with them, the chances of a final kick are looking extremely slim...

What's next?

> Six weeks to fitness!

Although a lactate profile can help map your strengths and weaknesses, Craddock was keen to get across that it's a highly effective way to monitor progression. Many of his clients will return every three months or so for repeat tests to see whether their training is working or not. If there is no improvement in the desired area, then it's a good indicator that a different training strategy should be undertaken. He added that this is particularly important for juniors coming up through the ranks who only have a limited time to make an impression.

Lactate testing might not be a new invention, but from what I've seen this is definitely not going to be the last time you're going to hear about it. I highly suspect that its prominence in the World Tour will increase. After all, if it works for Pogacar then everyone else will be keen to copy!

Then, there's the potential for real-time lactate monitoring looming on the horizon. Devices such as the K'Watch by PKVitality are already in development, and monitors like this could bring a whole host of gains for training and racing, allowing riders to monitor their effort to ensure they don't 'blow up'. 

The UCI being the UCI, there's a good chance technology like this would be severely restricted or banned outright; but I'd put good money on it becoming commonplace in both amateur and professional training over the next decade. Of course, like any data, it has no real value without the ability to interpret it.

> How to maximise your fitness when you get to 40+

For now, at least, lactate testing remains primarily in labs and a session like I undertook including consultation, the test itself and the post-test report typically costs around £160. Whether that's worth it or not will depend a lot on your ambitions as a cyclist, but I would argue that if you're looking to progress then a test like this will make a far bigger difference than a fancy carbon-railed saddle.

Thanks to Synergy Performance for having us along. You can check out their services, including remote testing, on the Synergy Performance website.

Do you think lactate testing has the potential to be the next big thing in cycling? Let us know in the comments section below...