These FTP tests and this blog were originally completed in 2018. 

TL;DR Summary - Does temperature affect your FTP results

• David from Dirty Wknd completed 4 different FTP tests at temperatures between 8 and 32 degrees. For science.
• The test measured FTP and weight loss, heart rate and cadence
• The results showed that FTP was highest in the warmer tests (32 and 25 degrees) 

Anyone who's ever done an FTP test, or multiple tests, will be able to tell you that it's not the most fun thing in the world. 

Testing your FTP basically means riding as hard as you can and tracking your average power, usually for 20 minutes.

Most people will do an FTP test at home on their turbo trainer (like a Wahoo KICKR), at an indoor studio like Digme Fitness, or possibly out on the road with an on-bike power meter.

Whatever your preferred method, it's always meant to be hard, and always (hopefully) rewarding, as you end up with some really useful data to shape your training.

So when Jake "The Kid" Neale, club member, ride leader and official 'youngest person on any ride ever' asked a bunch of us to help with his dissertation, we all jumped at the chance to help out.

Then he told us we'd have to do 4 FTP tests. In a heat chamber. At varying temperatures between 8 and 35 degrees. And we weren't allowed any water during the tests. All the fun then...

What is FTP for cycling?

Functional Threshold Power is basically the amount of power you can maintain for 1 hour. This might be 150 watts, 250 watts, or 350 watts, if you're a weapon.

Whatever your FTP number is, it gives you a reasonable idea of where your fitness is by telling you how much power you can sustain for a certain amount of time.

Most FTP tests don't last a full hour.  A usual test will last 20 minutes, whcih is more than enough.

You ride as hard as you can for 20 minutes, at the end of which you'll take your average power data and multiply it by 0.95, which gives you your FTP.

For example, if you average 245 watts over the 20 minutes, your FTP would be 233 watts. Read more about why FTP is important here.

Why is FTP important for cycling?

Knowing your FTP is important if you're tracking your fitness level, following a training plan, or just starting to take cycling a bit more seriously. It will allow you to determine your training zones and then accurately 'train to power'.

But for most recreational cyclists, it's not that important. It tells you what your current fitness/power level is. Which is nice to know, but if you're not following a training plan, that's all it is. 

Don't let FTP worry you if you just like getting out and riding your bike. It's just a number, and doesn't help you when you're suffering up a hill or sitting in a cafe. Forget about it and enjoy the ride. 

However, if you want to try and improve your fitness and/or FTP, or you're just a bit of an FTP nerd, read on to find out how testing at different temperatures can affect FTP.

Why ride multiple FTP tests at different temperatures?

Jake's thesis question was 'Do different heat conditions affect FTP?'

As willing lab rats, we were weighed before each test, put into the heat chamber for a 10-minute warm-up, followed by a 20 minute FTP test.

As well as analysing power output, Jake would be monitoring how much weight we lost in fluid during the tests. So no water between the two weigh-ins.

As part of the tests, we weren't allowed to know the temperature in the chamber until all 4 had been completed. We were also not allowed to have any data in front of us or to know what the results were, in case it influenced us.

So no water AND no data? I know cyclists who could just about put up with the water thing, but no data?

Below are my results from all four tests, as well as my pre-test notes (without knowing the stats) and then notes made whilst looking at the data.

Not to go all GCN here, but this is Dirty Wknd doing science.

Test 1 - February 1st @ 12pm

Pre FTP test notes: 

The first test was actually quite a nice temperature. 

At 5-minute intervals, Jake would ask us to relay our perceived effort, body temperature and room temperature. The effort and temperature reading soon rose to near max, and stayed there. I guessed that this was either the hottest, or second hottest test, but I couldn't be sure. 

It was pretty weird not having any numbers to look at, but it was actually quite nice to just focus on feel and ride accordingly. 

My guess at the temperature in the chamber was around 28 degrees.

FTP Results:

• Heat chamber @ 25°   
• Pre-test weigh in = 78.2kg
• Post-test weigh in = 77.8kg
• Weight lost = 400 grams
• Average Power = 286W
• Average Cadence = 101rpm
• Maximum Heart Rate = 189bpm
• Average Heart Rate =172bpm

Post FTP test notes:

20/20 hindsight is a wonderful thing. After seeing the results, I'm not surprised this was my best test.

The nice warm conditions felt like riding in Mallorca (without the breeze), and the fact that it was the first one meant I probably pushed harder through nerves/showing off.

It was also mid-week, so I'd recovered a bit from the weekend's activities. I wasn't sure what the weight loss meant, but 400 grams seemed quite a lot. 

I felt very dehydrated after the test, and was thirsty all day. One down, 3 to go.

Test 2 - February 5th @ 9am

Pre/during test notes: 

First early morning test. Being a Monday morning, I wasn't exactly thrilled to be doing an FTP test.

A bit worn out from racing on the Saturday and a long Sunday ride, I certainly felt a lot more laboured during the test. I did however feel a lot better about my hydration levels during this test.

Riding in the Vo2 mask is both annoying and disgusting. It's very hard to breathe, and it kindly collects your sweat for you. How nice. But you do sound like Bane, which is kind of cool.

I guessed that the heat in the chamber for this one was about 20 degrees.

FTP Results:

• Heat chamber @ 15°
• Pre-test weight in = 77.1kg
• Post-test weigh in = 76.1kg
• Weight lost = 1kg
• Average Power = 270W
• Average Cadence = 106rpm
• Maximum Heart Rate = 180bpm
• Average Heart Rate = 165bpm

Post test notes: 

It's pretty clear from the difference in weight lost through fluid that I was really dehydrated in the previous test. Losing 1kg of weight during 30 mins of hard exercise is mad.

My Heart rate is also a fair way off my maximum, so either I wasn't trying (didn't feel like it), or I was a bit knackered from the weekend. Probably the latter.

Test 3 - February 13th @ 10:30am

Pre/during test notes: 

When I arrived for test 3, Jake had kindly draped a towel over my handlebars, so I knew this one was going to hurt,

Walking into the chamber felt like entering an oven. It was a struggle to breathe, especially through the mask. The thick, hot air and lack of water gave me a sore throat after the test.

However, my legs felt ok, very similar to the first test. To say thank you to Jake, I left a huge pool of sweat on the floor. 

My guess for test 3's temperature = hotter than hell.

FTP test results:

• Heat chamber @ 35° 
• Pre-test weigh in = 77.1kg
• Post-test weigh in 76.4kg
• Weight lost = 700 grams
• Average power = 284W
• Average cadence = 101rpm
• Maximum Heart Rate = 189bpm
• Average Heart Rate = 173bpm

Post test notes: 

Surprised I didn't lose more weight in this test. Not surprised that power numbers are similar to the first test, as legs felt pretty good.

Also getting more used to riding on feel and getting better at holding a steadier power output. I felt a bit faint for the rest of the day, and no matter how much I drank, I was continuously thirsty. 

If nothing else, these tests are ensuring that I will definitely drink more on rides going forward.

Test 4 - February 19th @ 9am

Pre/during test notes:

Jake had again laid out the towel on my bike, so I thought maybe I'd guessed the temperatures wrong, and this was another hot one.

However, stepping into the chamber and immediately shivering, I realised it was a cruel joke. Multiple temp FTP tests and mind games - thanks, Jake.

As I'd only worn bib shorts or the first 3 tests, kit choice had to sadly remain the same. Safe to say I won't be riding in just bib shorts on any cold spring days, it's not fun. During the test, I felt a strange tingly sensation on my skin, and realised my body was trying to sweat. 

My Legs felt like utter garbage thanks to racing and the Hell of the Ashdown the day before. I was not excited to see my numbers after this test.

Pre-test chamber temperature guess = a few degrees below zero.

FTP test results:

• Heat chamber @ 8° 
• Pre test weigh in = 77.35kg
• Post test weigh in = 77.0kg
• Weight lost = 350 grams
• Average Power = 259W
• Average Cadence = 94rpm
• Max Heart Rate = 168bpm
• Average Heart Rate = 150bpm

Post test notes: 

Not impressive.

Looking at max Heart rate, it's clear that I was shattered. RPM and power were much lower than normal, but my perceived effort was still pretty high. 

What is most interesting is that I still lost 350grams in fluid despite the cold and the poor numbers.

If you think about a long winter ride, where you never warm up and hardly touch your bottle, you're still dehydrating yourself. It's important to keep drinking regularly to keep your fluid levels up, even if you think you don't need to.

Conclusion:

When Jake asked me to take part in these tests, I thought it would be cool to help him out with his dissertation, but also to get a load of stats to play with.

It turned out to be a lot more interesting than I'd first thought, and I learnt an awful lot about myself.

As a 'hot' person, I always thought I would suffer in hot weather, and sometimes shied away from really hot days. But it turns out I can handle the heat,  I just need a lot of suncream.

What these FTP tests have illustrated to me is the importance of proper rest.

No matter how hard I pushed in the final test, not getting above 168bpm is pretty damning. How can I expect my legs to do what I want them to if my heart isn't pumping as hard as when I'm rested?

So, along with drinking a lot more whilst out on rides (as well as before and after), I will be trying to rest properly between big efforts. I also learned that if Young Jake asks you to help out with something, it's best smile, start walking backwards, and fake a phone call.