Fatigue Resistance and why it matters...

Fatigue Resistance and why it matters...

I appreciate that I do 'bang on' about the same subjects each week, but a conversation whilst out on the bike on Sunday, has brought me back to the topic of 'Fatigue Resistance'. A paper just published by Maunder et al titled The Importance of ‘Durability’ in the Physiological Profiling of Endurance Athletes' was the first to kick off the interest in the subject, early last year.

In truth, 'durability' is nothing new but it's a timely discussion based on recent trends in triathlon training. There's been a trend for many years to focus on 'quality over quantity' which means that much shorter and more intense intervals have become the basis of many training plans. Riding or running longer and slower mileage is seen as a waste of time and discarded as 'junk miles'. The way in which we 'measure' our fitness follow suit. We prefer to use 'maximal' scores as a gauge of our fitness and progress. The VO2 max figure or the 20 minute FTP test for cyclists are 2 common examples. 

Is he going to bang on about FTP again!!??

Yeah, I'm sorry, I know I'm predictable, but I seem to be having the same conversations every weekend. If you don't know what FTP is, it's the amount or power you can supposedly hold for 1 hour whilst cycling. I say 'supposedly' because nobody actually does the test for 1 hour, instead they do a '20 minute test' or an even shorter ramp test and 'guess' what it would be for an hour.

In 90% of cases, the predicted (guessed) FTP score is unrealistic and the athlete would not be able to hold it for a full hour... because they don't have the durability. But who cares, it's all about that number, so if a shorter test predicts a higher score, that's what counts eh?

So back to the paper on 'durability'... Let's put this in really simple terms. If you do an FTP test and your predicted FTP is 250 watts, that's all very well. But you probably did  20 minutes warm up then a 20 minute test, then a cool down. So all in all, you most likely did less than an hour of cycling. If you're only racing short distances such as 10 miles TT or sprint triathlon, then all is ok, but if you're racing long, then there's more to consider. 

If you're racing Ironman this year, then the question to ask is "what's your FTP at the 50, 70, 90 & 110 mile point? Lab or exercise testing is generally done when you're rested and following a short warm up. We then calculate an FTP figure which we presume is static and doesn't change, but that's not actually true. 

Your FTP at the 90 mile point will likely be much lower than when you did it rested in your garage, it changes depending upon your level of fatigue. So can we really say FTP is an accurate predictor or Ironman bike performance? If you warm up for 20 minutes, then do a 20 minute test to 'predict' FTP... the chances are, it'll over-predict and give you a figure which is too high. To think that you can use that same 20 minute test to predict your 'Ironman pace' is nothing short of ridiculous. 

If you're racing long, 'fatigue resistance' is key

To back this up, let's consider a fantastic piece of research published last year by James Spragg of Spragg Cycle Coaching. The paper has been a recent topic in Outside Online under the headline of 'Fatigue Resistance'. James works with professional cyclists and was given access to power data from the UCI teams Bora Hansgrohe and Androni Giocattoli. 

To explain the study in simple terms, James wanted to see how fatigue impacted professional rider profiling. There was some really interesting information to come from the research. He noticed that when doing lab testing, the younger U23 riders were producing scores which were just as good as grand tour winners. The difference was, that the grand tour winners could produce similar scores even at the end of a hard 6 hour race. In simple terms, it ain't just about what you can push... it's about what you can push in the final 30 minutes when everyone has been riding hard for 6 hours...

For Ironman competitors, the message is simple. It's not what you can push on a 20 minute test, it's what you can sustain for a long period of time which will determine your outcome. I'm not saying FTP isn't important, but I am saying that it’s only 1 piece of the jigsaw and there's way too much focus on a golden number which won't help you in Ironman if you're in limp mode when you reach 90 miles on the bike. You could apply the same to running, does it really matter what your 5k time is, if you're walking at the 18 mile point in your marathon race? 

The reason we like to do the 20 minute test or the VO2 max score is because it's simple and we can quantify it. It's give us a 'number' which we can compare with others and use to measure our progress. How do you 'quantify' your ability to keep going for a long time? What's the number or the score that you can use? But maximal scores are misleading. For most people, the very training which will increase your 20 minute or maximal output is the polar opposite of that which will improve your Ironman or ultra performances. 

Economy will always be the major physiological determinant of Ironman or ultra performance. You need to swim 2.4 miles, ride 112 miles and get off feeling ready to run a marathon. The terms 'durability' or 'resilience' are more reflective of the qualities required to stay the distance during longer events. By contrast, the word 'maximal' will have far less of a bearing. 

We offer VO2 and lactate testing to more accurately calculate your training zones and assess your physiology. Our Ironman coaching package costs £40 per month and begins October 3rd. You can read more by GOING HERE

Marc Laithwaite is a level 3 qualified coach, who has been coaching endurance sports for the last 22 years. He is a former sports science lecturer of 12 years and spent 2 years with the British Cycling team as a bloods analyst. He has worked with British Triathlon Coach Education as a coach educator and spent 5 years as head coach of the NW Regional Triathlon Talent Squad. He's also a former national age group triathlon champion, European duathlon champion and Ironman age group winner. His 6 & 8 year old daughters can beat him in a 50m sprint, but their fatigue resistance still needs work.