Phosphate sprints: The ultimate bike session?

Discover how short and intense sprints can benefit your cycling fitness, but also how can they gauge fatigue and prepare the body for a race.

You might have never heard of phosphate sprints, but you soon will. Which is a good thing as they could transform your cycling performance forever.  

A phosphate sprint session is the pedalling panacea you've been waiting for. It's a session I use with the professional cyclists I work with, and I have used them for many years, including when I worked at Tinkoff-Saxo with Alberto Contador and Peter Sagan.

These sessions are not time consuming and they can boost immediate power. At the same time, they can gauge your level of fatigue and play an integral role in your race-week build-up.

Let me explain why, and how.

Related – What are strength efforts?


Phosphate sprints are short, maximal intervals of 5 to 10 seconds, which is more than enough time to hit peak power, but insufficient to produce lactate. More specifically, intervals performed at maximal intensity for a short duration are powered by the creatine-phosphate system. This is a unique short-term energy reservoir and it’s distinct from any other energy production system in the human body. 

Training the creatine-phosphate system with these short efforts makes it possible to increase your body's creatine phosphate storage (CP). The greater the amount of CP, the more bullets (short, intense efforts) you can fire when you're pedalling out-of-saddle or moving up the peloton, for example.

There are several other examples of when a full-gas, short effort is required, both in racing and in training. Therefore, improving the capacity of your creatine-phosphate system is always going to be an asset.


But there's more. The ability to hit high numbers while performing phosphate sprints also indicates a rider's freshness or fatigue status. Fatigue can present itself in many different forms. One that receives very little airplay is called neural fatigue. This is an involuntary reduction in voluntary muscle activation. When neural fatigue has set in, performance suffers because the rider does not feel 'sharp.' Often, riders say they feel flat or uncomfortable getting on 'top-of-the gear.' 

In these scenarios, what happens underneath the surface, is that the speed at which the rider can fire up as many muscle fibres as possible (motor recruitment) is impaired. And less muscle fibre recruitment equates to less power to the pedals. 

This is where phosphate sprints can be an accurate and low-risk option of assessing how a rider is recovering (and they will not produce high level of lactate in the body). If riders are way off their 5-10 sec peak sprint numbers, and display other symptoms such as lethargy, then it's likely they're in a state of neural fatigue and should ease off.


A great routine that's stood the test of time is the 5 x 5 seconds phosphate sprints with 55 seconds recovery in between. The total time for the set is just 5 minutes, though you can increase the set number depending on your experience. Allow a minimum of 10 minutes recovery in between each set. You can also increase the session's difficulty by riding 5 x 10 seconds phosphate sprints with 50 seconds recovery in between each sprint. Here's how to perform it:

  • Make sure you're warmed up before performing these maximal sprints.
  • Find a long, flat and quiet section of road. Select your sprinting gear and slow down to around 10 km/h.
  • Get on a sprinting position, which is head down and hands in the drops.
  • Then perform an all-out, out-of-the-saddle sprint for 5 seconds. It's easier to count the seconds in your head than watch a head unit.
  • As soon as the 5 seconds are complete, hit the brakes and slow down.
  • At a slow rolling pace, recover for 55 seconds.
  • As you approach the end of your 55 seconds recovery, begin to set yourself up for the next 5 seconds maximal sprint: choose the correct gear, slow down to 10 km/h and get on a sprinting position again.
  • Once again, perform an all-out effort off-the-saddle for 5 seconds and repeat the process for the number of reps and sets you've planned.


Phosphate sprints are not only a great way to increase power and measuring fatigue. There's another benefit to them: they’re also great for pre-race activation. For example, let's assume your race is planned for Sunday. An excellent pre-race plan is to have a solid workout on Thursday, and Friday will be a rest day or a recovery day. However, the Friday session (or rest) will effectively switch the body off. This is because the neural activation from Thursday's hard ride has been dimmed down during Friday's easy day. The low neural activity continues into early Saturday. The result? By Saturday lunchtime, you would feel tired, which seems counterintuitive because you've been taking it easy for a day-and-a-half. 

So, now you must wake up. But you should do that at a minimal energy cost, and with as little impact as possible on your hydration and glycogen status. So, what kind of intervals are the best to switch the brain back on while not affecting the internal fuel reserves or upset your hydration levels? You've got it, the phosphate sprints.

Try this simple pre-race activation ride the day before your race:

  • Race day is Sunday, so your activation ride should be performed as late as possible on Saturday afternoon. Around 1-2 hours of riding is usually enough to wake up a rested body.
  • In the first hour, perform a series of random accelerations. Sprint for street signs or maybe a little squeeze on the pedals for 10 seconds as you crest a small climb. Anything that makes you feel like a bike rider again.
  • Then prepare to get on the sprinting position near the end of your ride.
  • Perform two sets of 5 x 5 secs phosphate sprints with 55 seconds of easy pedalling in between.
I promise, this session will make you feel like the lights are back on.

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