• Boris Clark

Going faster makes you slower (as an endurance focused athlete).

I see a lot of people deciding to focus on short hard efforts in the region of 30 second to a minute in order to improve as a cyclist or runner by adding ‘speed’ or ‘power’.


The thought is that if I can ride at 800w for 30 seconds, or run at 2m30s/km pace for 30 seconds, then surely riding at 275w or running at 4m30s/km pace, which you may aim to do for an hour plus depending on the athlete is going to become a lower proportion of this figure, and therefore easier.


Even worse is the theory that these efforts create a large ‘TSS’ score (Training stress score) which will then translate to improved performance. TSS is simply a metric to give an overview of training load. It is not a measure of performance or how effective training is!


This couldn’t be more wrong. Physiology doesn’t work like that. The energy system which allows you to either ride at super high intensity for a short period, or at moderate-high intensity for a longer period cannot be optimised to do both! It’s physiology impossible.

First let me give an example/analogy, then I’ll give a brief overview of the physiology why this training will have the OPPOSITE effect of what people doing this sort of work intend it to.


The example

Take Usain Bolt at his prime. Running the 100m in under 10 seconds, and 200m in just over 19 seconds. Would you prescribe him 10minute long intervals at 4m30s/km pace for training?


Of course not!!!


You don’t need to understand bioenergetic pathways to know that this sort of training would make him slow and ‘diesel’ even if he retained all of his short intensive sprint work.


Usain bolt doesn't do long slow endurance training to get faster. The physiology to sprint fast is at odds with endurance performance

The reason these efforts make him slow isn’t because he would have to ‘focus less’ on sprint interval training or the like, it’s because the physiological changes this type of interval create make it impossible to generate ATP fast enough to sprint at this high pace any more.


These ‘long’ style efforts would help Bolt develop aerobic capacity, which contrary to what you might think is still a small factor in particularly 200m sprinting. It may not be a dominant feature of performance in this event, but having a greater aerobic capacity will still provide an advantage.


I ask you, if doing long efforts will make a sprinter slow, why are you expecting sprint efforts to improve your endurance?


The science

When we are measuring ‘classic’ endurance performance, one of the best ways to do this is to measure power/pace at the lactate threshold. As we have mentioned before, the lactate threshold is simply the point at which lactate PRODUCTION is equal to LACTATE combustion/utilisation (it is your carbohydrate fuel source after all!).


If you want to sprint fast for short bursts such as the 30 seconds we mentioned, you need to be able to perform anaerobic glycolysis at an extremely fast rate. This process yields us a few ATP for energy extremely quickly, but we produce lactate in the process.


Therefore, if you train your sprint you will increase lactate production at all intensities as you are enhancing your body’s ability to produce energy rapidly through anaerobic glycolysis.

If you want to improve your endurance, FTP, or marathon time, you need a higher lactate threshold, and that isn’t going to happen if you increase your body’s preposition to create lactate!


Eliud Kipchoge, the world record marathon record holder has a high aerobic capacity and running economy, but also an extremely low anaerobic capacity. This allows him to sustain such a high percentage of VO2max for the marathon

So what do you want to do to improve this?


Well aside from improve aerobic capacity (which we already mentioned, is good for everything), you will want to decrease your production of lactate at every intensity. Avoiding super high intensity short interval work is the first way to do this. It sounds counter-intuitive, but to train your body to produce less lactate, you need to de-condition the anaerobic system.


We all know that if you don’t train something it deteriorates, and this is exactly what you need to do as a first step to improve the lactate threshold and endurance. Want to decrease it even further to raise threshold power/pace further? This is where well planned and focused endurance interval training at the correct intensity becomes critical. This may be further enhanced by some dietary modification.


Want to know where your thresholds sit? How your aerobic and anaerobic energy systems compare? Want to know what training to do to optimize performance of both? Then don’t hesitate to get in touch!