This lactate testing can be a bit mysterious for people. I thought you might like to know how it works. I really like the way we do it, because its the scientific gold standard for testing. I know you could google lactate testing yourself but I thought it might be useful if I explained it in my own words, and showed you what a test looks like.

Like anything scientific, the gory details are pretty complicated and this description doesn’t do it all justice, but it isn’t supposed to. The point of this is to describe the Fitlab testing process rather than the intricacies of cellular metabolism, but there is a wee bit of crossover…


The purpose of the testing is to determine your training levels and zones.

Boring Bit [The current understanding in sports science, is that there are critical metabolic cellular respiratory developments that are occurring in you, as you cycle at different power outputs. i.e. how your body is producing energy at a range of outputs. We also capture the corresponding heart rates, in case you don’t have power to train with. This data forms the basis for determining the outputs at which you should exercise, for a given training stimulus and adaptation.

The gold standard for determining your cellular metabolism developments during exercise is blood lactate measurement. If you want to get hardcore and heavy on the detail about hydrogen ion creation, its relationship to lactate, and the pyruvate cycle be my guest. I won’t go there right now. Suffice to say, the accumulation of blood lactate in standardised testing very accurately corresponds to the way your body is producing energy. You want to know this because then you know where to train to elicit desired training adaptations. Its a system used for many years by professional cyclists, with a good body of scientific evidence for its efficacy. ] End of Boring Bit.

The data you get back in your Fitlab report, has all of your training levels, and zones, so you can train in the certain knowledge that you are doing 100% quality with zero junk miles. If you want to improve your anaerobic threshold for example, well, this tells you where it ACTUALLY IS. No guesses – the actual number – bang on.

The Test:

We perform the actual testing at Owhiro Bay in Wellington.  We can actually use any location that fits the requirements of the protocol. It can even be done indoors on a turbo trainer if needed. Its better outdoors because the wattages get skewed on the trainer, by about 8% low. But of course we can account for that if really necessary, so if you want an indoor test, thats fine. I can even bring the gear to your office.

You don’t need to have prepared particularly differently for the testing. You just want to be reasonably fresh, and ready to do a decent hard ride! You just need your bike, gear, helmet, shoes, computer, something to drink and or eat etc. If you have a power meter then great, if not, we supply one for the test. Bring your heart rate monitor. If you don’t have one we will supply.

1: I usually like to have a good chat to understand what the client understands about the process, their goals, answer any questions/ concerns etc before starting. We can also discuss any medical issues that are highlighted in the pre-test questionnaire.

2: You get your arm squished by the blood pressure machine. I determine your body fat using 2 methods for accuracy: callipers and electronic. You’ll get back both numbers. You’ll have your body composition measured by the super duper electronic scales, with fat and mass, water, bone, etc recorded for all body segments. Its good to keep a record so you can determine if you have put on fat or muscle over time. You even get a metabolic age estimate, which is often soothing for the ego, but occasionally catastrophic. If the latter, it’s a sign to put down the pies.

3: Time to get on the bike. We will check everything works 100%, before you pedal down the road, warm up, have a wee, and meet for the test briefing.

4. Testing: You pedal up the test sector at a pre-determined average wattage. You want to pedal up at as close to that wattage as possible. Now, don’t panic, because your wattage will fluctuate quite a bit as you pedal along. if you are aiming for, say 200 watts, you are gonna see your wattage swinging up and down from 180 – 220 watts or so, but the main thing is keeping it as close as possible to the target, and getting your average as close to the target as possible so that by the end of the sector you are pretty close to the target. It doesn’t matter if you muck it up a little bit. If you are supposed to do 200 watts but end up on 205 average that’s fine. No-one ever gets it absolutely perfect. When you are close to the end of the sector (it takes 3 – 5 mins) you look down at your computer and take a note of what your heart rate has stabilised out at. You remember that, plus the actual average watts you did. Don’t worry – its not complicated. You CAN remember the 2 numbers I promise. That’s when you pull to a stop behind the Fitlab Panzer. I will take a sterile blood prick sample from one of your fingers, for analysis by my nifty lactate monitor, and ask you the heart rate and wattage numbers. The machine spits out your blood lactate in mmol per litre of blood, and I go “…ooooh, yes very good, very good…” and note it all down.

Then, you turn back down the hill, pedalling at around 50 watts, before repeating the sector again, this time a bit harder, usually 30 or 40 watts depending on the person.

Normally, we go for 6 or 7 samples. You go until you reach your maximum wattage you can hold for the sector. Only 2 dudes have puked in the last 6 months so thats pretty good odds.

This data goes into your report and forms the basis for your lactate curve.

The whole thing takes about 2 hours normally. If really pushed I could do it in 90mins if you were in a hurry. You get your report back within 48hrs, and a follow up conversation to go through it all. The cost, as I write this, is $150 but you get a $20 discount if you get a training plan too.

Q1: One thing people often ask is if the wind affects the data. Nope. Power is power, So whether you have a howling headwind or tailwind, the relationship between your power output and blood lactate is the same. You’ll be going faster or slower of course but it doesn’t affect anything that we are measuring at all.

Q2: Frequency: Normally its good to get tested every 3 months or so, if you are training, because your levels will change as you train. I test myself every 3 months or even more if I’m training a lot.

Here’s what the Strava record of what my last test looks like:

Above: The overview. 1hr:19min of riding including the warmup.

The test route is a segment in Strava. You can see the power going up by about 40W every time. This day was a little headwind, and you can see the time for each run is between 6 and 3 mins or so. If its a tailwind it would be a bit faster. It doesn’t affect the testing though.

The actual data.

Some of the key data extracted from the testing: 1mol = 201W/ 113BPM 2mol = 315W/ 142BPM 4mol = 358W/ 152BPM  AT = 4.52w/kg/ 66.2% VO2

So, I have a little bit of work to do to really be where I want. There’s lots in there, but one thing to pick out thats often valuable is weight to power at AT. 5w/kg at threshold is generally a really good level for me. My body fat tested around 9%, so I need to get that down by about 3%, and bring my threshold power up another 20 watts or so to hit that. I was a little tired so potentially theres a wee bit of power there but probably not 20W. I know I’ve tested over 5w/kg at threshold before so I know I can do it, it’s just a matter or focus. Now that I have the data, I can do specific efforts and drills that target the key energy systems for my events, and I know how far I need to go. I really like using this stuff in combination with Strava Stalking to determine target times for key climbs in events.

If you get a program from me, I’ll figure all of this out for you and do an entire program. I’ll review 100% of your key rides, giving you feedback notes in the software you get, and catch up with you as often as your plan determines, to develop the next phase and talk through what you’ve done. I won’t shout at you or make you feel bad…Unless you are into that.

I love it and I love working with my clients. There is nothing more exciting than working with an athlete and seeing their numbers improve – in black and white – no guesswork.

If you’d like testing, just give me a call or email on my contact details up the top of the page. I can work in a time that suits you.

Happy Trails,


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