Fatigue Resistance and why it matters...
There's been some great chatter on Twitter this week, around the topics of 'durability' and '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 truth, 'durability' is nothing new but it's a timely discussion based on recent trends in triathlon training. In my view, there is a growing obsession with FTP. In some ways, it's become the new VO2 max, it's the golden standard by which people rate their cycling performance. Unfortunately, it's become the sole focus for many and as a result, they fail to focus on other critical aspects of training.
My first bugbear with FTP as I've posted before, is that nobody actually does an FTP test. Your FTP is the amount of power you can hold for 1 hour, so if you want the figure, go and ride as hard as you can for 1 hour and check your average power. However, most people predict it by doing a 20 minute test or an even shorter ramp test. In 90% of cases, the 'predicted 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.... but it's not.
Your FTP at the 90 mile point will likely be much lower than when you did it rested in your kitchen, it changes depending upon your level of fatigue. So can we really say FTP is an accurate predictor or Ironman bike performance? Or is durability (the extent to which your FTP decreases throughout the ride) the most important thing? Let's add 'training zones' into the equation... if your 'power zones' are based on FTP and your FTP is 30% lower at the 90 mile point, are your zones accurate?
To back this up, let's consider a fantastic piece of research published earlier this 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 upon rider profiling. So he noted how much power can they produce when fresh and how that compares to the power they can produce after a 6 hour hard day, at the end of a race. They compared GC riders, domestiques, older and younger riders and the simple message to take home was, it's not what you can push during 'a test' when rested... it's what you can push when it counts at the end of a race. The younger riders (U23) had very high power scores (when fresh), showing little difference with the adult pros, but after several hours of riding, their scores deteriorated, far more than the adult pros. As you'd expect with the best riders and GC contenders, they could ride all day and then still produce incredible numbers.
Now... whether you're calling it 'durability' or 'fatigue resistance' 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 if you're in limp mode when you reach 90 miles.
Mileage is not necessarily garbage and quality does not necessarily beat quantity.
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 5 & 7 year old daughters can beat him in a 50m sprint, but their fatigue resistance still needs work.