You can purchase a lactate test to complete at home nowadays - should we be abandoning FTP tests in favour of a more scientific approach?

The classic ‘FTP test’ has long been the gold standard method of determining the power a cyclist can sustain for one hour - their Functional Threshold Power (FTP) - which is then used to determine their training zones during structured sessions. This is not only a great barometer of fitness, but can be carried out for free in the comfort of your own home. Knowing your FTP allows you to ensure you’re training intervals in the correct zones - hard enough to progress, not so hard they’re achievable - and track your progress.

The 2010 test concocted by Andy Coggan and Hunter Alan has riders complete a 20-minute all-out effort, before multiplying the resulting number by 0.95%. Other means of testing have since arisen: the ramp test, and the 2 x 8 minute. They all have one thing in common: the rider goes as hard as they can for a given period of time, and their success determines the number at the end.

But, is there another way?

At-home lactate threshold tests are becoming increasingly popular among amateur athletes. They can be purchased for as little as £70 but standard models usually start at around £200. It’s usually recommended that you start off with a test in a lab - that’ll set you back around £150 – but then you can track future fitness adjustments at home. These tests are arguably more scientific and less open to being influenced by the rider’s familiarity with the test, because they look at your fitness levels and arrive at numbers based on blood samples. There is no ambiguity here – a lactate threshold test takes an objective view of your cycling performance. But are they accessible enough to replace traditional methods? I headed to a lab to find out.

Lactate tests: the basics

Lactate builds up in muscles during exercise, and a lactate threshold test records the amount accumulated throughout an effort. The test can either be carried out in lab conditions or at home. The rider begins pedalling at a fairly comfortable pace, and the power required is increased in increments, usually every three minutes or so. A blood sample from a pin-prick on your finger or earlobe is taken at the end of each power interval. The test usually finishes when the rider is producing a power figure just above their FTP.

The tests looks for two significant inflection points: Lactate Threshold 1 - or, aerobic threshold - at around 2mmo/l, and Lactate Threshold 2 - anaerobic threshold - at around 4mmol/l; the latter is thought to be around 95% of your FTP.

You can buy these tests to carry out at home, where you’ll take the lactate samples yourself. However, an initial test in a lab environment is a good idea as a sports scientist will be able to guide you through the process and help identify the inflection points and take blood samples. After that, you can take these learnings and do it yourself, as most riders want to keep an eye on their FTP and its progression, adjusting the figure over time as they (hopefully) become fitter.

Trying a lactate test

Keen to put the theory to the test, I located a laboratory, told them I was on a quest to find my true – physiologically precise – training zones and booked myself in for an hour that would result in blood, sweat and -not quite - tears (but they weren't far off).

Precision Fuel and Hydration welcomed me into their lab where a Wahoo Kicker Bike was set up opposite a big screen TV with a display bursting with metrics. Dr Sam Shepherd would be overseeing the test today and I couldn’t help but notice he was wearing surgical gloves.

Firstly things first, a baseline reading was taken. I was told anything around 0.9 - 1.2 was normal at rest and as usual my mediocrity shone through and a lactate level of 1.1mmol/l was recorded. The test started at 120 watts and rose in increments of 30 watts every three minutes with a blood sample being taken at the end of each interval. It took a while for the readings to settle into a linear pattern with the first few samples increasing and decreasing, but once I’d warmed up and my legs were turning the pedals fluidly, the pattern became more uniform and I settled in for what was ultimately a test to failure.

The first notable uptick in lactate production came at 18 minutes in. With a heart rate of 139 and a power reading of 270 watts/3w/kg, there was now 2mmol/l of lactate in my blood, and this combination indicated my true ‘zone 2’ - a state of fairly easy endurance pedalling. Interestingly, the figure was slightly higher than I'd previously thought based on traditional training zones, so, the learning means that my endurance rides may become a little more taxing in future.

Then came the painful part. With fatigue already present and the power increasing every three minutes, the next lactate spike Dr Shepherd looked out for was around the 4mmol/l mark. Unlike true zone two which is more or less physiologically imperceptible, it becomes very apparent when you’ve reached lactate threshold 2. The inability to shuttle lactate between muscles produces a hydrogen iron build up and discomfort sets in. For my harder rides then, intervals of around 343 watts or a heart rate of 162 were specified by the test – this is a number that’s largely recognised as 5% below FTP. Given that my FTP is 260 watts, the figure is pretty much bang on at 4.9% lower, and means my harder intervals will be ridden at around the middle of the traditional 'zone four' band.

Are lactate tests worth the outlay?

Lactate testing is a means of truly determining your fitness levels. Where variables such as muscle fatigue, sleep, temperature and time of day could potentially affect the outcome of an FTP test, a lactate monitor will always remain objective and give you a highly accurate snapshot of your current aerobic and anaerobic ability. That's why I'd recommend this style of testing over the traditional FTP test: the numbers you'll be given will be based upon physiological data that isn't open to the same influences.

Is it worth buying a monitor yourself? I would say certainly – if you’re a serious cyclist who wants to know the precise heart rate and power at which you should be pedalling on easy and hard days, it’s a no brainer. Spending time at your ‘true’ Zone 2 - or Lactate Threshold 1 - is the most efficient means of building endurance, and likewise spending time at Lactate Threshold 2 is a highly productive way of raising your high-end power. I was surprised to find that my Lactate Threshold 1 - 'true zone 2' - was higher than expected, taking my endurance rides up a notch, and having a reliable figure for those harder Lactate Threshold 2 efforts means I can prescribe tough sessions, accurately.

There is certainly still very much a place for FTP tests, but if you really want to study your performance at a more enhanced level, regular lactate testing can’t be beaten.