Anaerobic Speed Reserve (ASR)

The Anaerobic Speed Reserve (ASR) has been used for many years in sports science and endurance coaching, specifically for running. As usual, it tends to be over-complicated and over-scientific, but the basic principle is one of the most important things that you could ever understand as an endurance athlete. There’s a lot of research into ASR, which if you’re that way inclined, is only a google search away…

ASR in simple terms is the difference or the ‘gap’ between your ‘maximal aerobic speed’ and your ‘maximal speed’. ASR is a ‘running thing’ but you can use it for cycling too. We use ASR to some extent during our cycle tests. Your maximal aerobic speed (or power) is the power you produce on the last minute of your ramp test (the one that goes up each minute). You maximal speed (or power) is the peak power you hit on the 10 second sprint test.

I’ve posted a video before which explains the purpose of the bike test, but let me recap. Every time you visit us to complete a bike test, we hope that you will get further on the aerobic ramp test and your power:weight figure will therefore improve. We need to work out, what is your limiting factor… what’s stopping you getting to the next minute? There’s 2 simple things to consider:

  1. Are your legs just not strong enough?
  2. Is your aerobic fitness the issue?

By doing the sprint test, we can get a simple gauge of your maximal sprint power. If your sprint power is above average, then we’d assume that it’s not your leg strength/power which is letting you down, it’s aerobic fitness. By contrast, if your sprint power is poor, you may fail on the ramp test simply because you can’t produce enough force…. You may not reach your VO2 max and you may not even be near max heart rate… your basic leg strength/power is just not good enough. Those of course are the 2 extremes and most people sit somewhere between. So… you can see the importance of looking at those 2 simple things and how we can profile you.

Transferring ASR to running

Whilst the above example explains part of our cycle testing, ASR is generally a running term. So, replace the above examples for running based scenarios. If we tested you on the treadmill rather than the watt bike and did a ramp test, increasing the speed every minute until you had to jump (or fell) off, the last minute would be your ‘maximal aerobic speed’.

If we then took you to a running track and measured your maximum velocity during a 100m sprint, that would be your ‘maximal speed’.

There is a bucket load of research which links the 2 things together. In elite distance runners, there is significant correlation between ‘maximal speed’ and ‘maximal aerobic speed’. In simple terms, the fastest 10k runners in the world, are faster over 100m than all the other 10k runners.

Much like the cycle testing above, what we want to know is ‘how can you get faster over 5k?’… What is the limiting factor? And as above, the 2 things to consider are:

  1. Can you simply not run fast?
  2. Is it your aerobic fitness?

What’s important to understand is that question number 1 – Can you not run fast enough? That’s got nothing to do with aerobic fitness. It’s about producing force with muscles and tendons, it’s about nerves sending signals so quickly that your legs can move at speed, it’s about how you land, store energy and push off and it’s about doing all of that, at speed, in a smooth, fluid and relaxed manner. It has absolutely nothing to do with blood, oxygen and aerobic energy. Running fast for 100m is NOT an AEROBIC activity. That’s why the fartlek sessions should be extremely short (50-100m) at speed, then long recoveries.

So, to assess your ASR you could ask yourself the simple question… is your 100-200m fastest pace SIGNIFICANTLY quicker than your 5k pace? If not, then that’s possible the key to unlocking your speed. By contrast, if your 100m-200m fastest pace is pretty good, but your 5k isn’t… then you’re probably quick enough but lack aerobic conditioning. As always… many of you will fall somewhere in the middle.

On the plus side, your maximal speed can be increased very quickly. Your nervous system adapts over a series of weeks, whereas aerobic endurance takes months or years. That’s the bonus of doing pure ‘SPEED’ work such as 10 X 100m fast/flowing, it has an almost instant effect, so it’s easy to throw in 4 weeks before a big event.

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