Kaboom! How to Avoid Bonking on the ride

By Alun “Woody” Woodward, coach, 

You’re flying along enjoying your first Ironman then you hit 120km and KABOOM!!

How many athletes experience this at 120km in an Ironman ride, it’s amazing how often this happens and athletes have a very logical but false impression of how to prevent this. Our natural response is we do not have enough endurance and therefore need to do more long rides and runs!!

Ironman is a scary prospect and as such we all make damn sure we get the long rides and runs done in preparation to prevent the KABOOM moment but so many times it still happens. Most athletes will ride 5-6 hours for their long training rides or at least try to get one ride of 180km done in preparation so is this experience of blowing up really due to lack of long ride distance?

Then we have the athletes who cope fine with the bike and hit the run only to end up walking after 5km and start thinking they are lacking run endurance.

So what is going on and why do so many athletes experience this at 120km into an Ironman bike? To understand this we need to look at what happens and what training effect we get from our long easy rides.

The long weekly ride that is a fundamental of any training plan tends to end up being an easy ride focused on distance. When we ride all easy like this we end up training only a very small part of the muscle. If we look at how a muscle is made we can simplify things to say each muscle is made up of 100 fibers, to bring about a movement we need to activate a certain number of these fibers and our brains control this and brings about movement in the most efficient way possible. When we ride easy our brains will use maybe 20-30% of all the fibers as these are the most efficient and energy saving for this intensity.

What we have to think is our brain wants us to survive and does this by using as little energy as possible for everything we do. The more we train, the more our brains learn to use less energy so we become more energy efficient – a great adaption for endurance performance but in extreme examples like Ironman, we run into problems as once we hit that 120km point, those efficient fibers for endurance suddenly hit a point of fatigue and stop working forcing other fibers to have to take over the role. If we have not trained those other fibers once they come into play we will feel a little uncoordinated and then they fatigue so fast that we get that KABOOM moment as we have nowhere to go from there!!

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So when looking at training endurance for Ironman, we need to look beyond the simple long endurance sessions in order to get through the race without that KABOOM moment and to optimize performance.

In order to do this we need to find a way to train more of the muscle fibers and share the workload over more fibers so that point of fatigue is pushed back and performance increases.

What we essentially need to do is trick the brain and force the body to switch on more muscle for a given task. This principle has been used very successfully in body building but is not really considered when looking at endurance training. In body building it is common to start a set of lifting heavy then reduce weight and increase reps to get a much bigger response. The first heavy lift forces the brain to activate all the muscle fibers and then the following lifts at reduced weight will still hit all the fibers but with more reps we get a more rounded training effect with enhanced strength and size in all the fibers.

So how do we apply this to bike training to enhance endurance?

Let’s look at 2 ways we can change the endurance bike day to bring about enhanced endurance adaption in a wider range of muscle fiber.

Firstly let’s look at a long endurance ride of 5 hours, I want to increase the endurance element but I do not want to extend the ride. I would do this by placing some low cadence high power work very early on in the ride to fully activate muscle fibre recruitment in the bike specific muscles and then later in the ride the focus would be on race cadence work, for example:

5hour ride to be ridden as

  • 30min easy warm up
  • 2x20min in biggest gear pushing hard against resistance with 10min easy between
  • 3hours easy
  • 30min hard effort @ race cadence
  • easy cool down

By setting the long weekly ride this way we get an endurance training effect in a much greater percentage of muscle fibres. The result being on race day we have more fibers trained to share the workload and therefore, increase endurance.

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Another way we can get a similar training effect is to add a double bike day into a training week, these sessions only need to be short but can create a huge gain to both speed and endurance.

So let’s say you have an hour to train in the morning and the evening, this is one way you can set the sessions to enhance endurance.

Morning session – 1 hour including 30minute of hard intervals at low cadence

Evening session – 1 hour including 20 minutes of intervals at race cadence or above.

What we want to happen here is to totally fatigue the biking muscles in the morning session and then as we start the evening session we force the brain to activate more fibre to get the work done. A very unpleasant experience when you start as the evening session has your legs burning with very little speed gain for the effort but as you adapt and build fitness you will start to fly in the second session and really see a big change to both speed and endurance come race day.

Want to have a great ironman performance and avoid the 120k KABOOM – follow the advice above and rather than increase the duration of your endurance rides simply change the content to get a much bigger training effect that you will really feel come race day.

Enjoy your training.

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