Before we delve too deep into this topic please rest assured that if you are suffering from Aerobic Deficiency Syndrome it is completely reversible but identifying it and addressing it is the important first step.
As a runner, most of us know the importance of building an aerobic base as our foundation. The aerobic base helps us to run further and faster in preparation for our 'A race' during that forthcoming season. In reality though, how many people truly run at the correct speed to ensure they are training aerobically? To give some context, let's look at a couple of key markers to determine training and help us understand if we're training correctly based on the sessions intended outcome. Whilst the terms described below have caused some debate and been used interchangeably (causing much confusion in many books and forums), they are useful to help understand energy utilisation and therefore intensity of training. Understanding these ensures we are getting the right stimulus.
Aerobic Threshold (AeT): This represents the uppermost limit of exercise when the production of energy is no longer primarily from the oxidation of fats. Once we pass the aerobic threshold, we start to see re-synthesising of energy coming from glycolysis (sugars) and with it, a build up in lactate, and over time, this build up of lactate hinders performance. This threshold should be seen as one of the most important markers when it comes to developing aerobic capacity and endurance performance.
Anaerobic Threshold (AnT but also referred to as lactate threshold): This represents the lowest intensity in which the production of lactate begins to exceed the body's ability to utilise it as a fuel source in aerobic energy metabolism. In addition to lactate, another byproduct of glycolysis is pyruvate. If this is produced in manageable quantities it can be utilised aerobically - producing no waste products. However, if it accumulates too quickly for the aerobic system to utilise, it begins to build up in the muscles and cause a reduction in speed/performance. Simply put, your anaerobic threshold is the maximum intensity in which you can sustain a given pace for around 60 mins. Exceeding this threshold will cause reductions in performance over time, depending on the intensity relative to this threshold.
Why does any of this even matter? As pointed out, these thresholds are relevant to the use of energy for fuel. For running and endurance sports we want to maximise the body's ability to produce as much energy as possible aerobically. Through the oxidation of fats, aerobic energy production creates no waste products and can be sustained for very long periods. So, if we develop our aerobic threshold, over time we can increase the speed at which we run, whilst utilising mostly fats as fuel and reducing the production of lactate.
It is also important from a performance stand point when it comes to training. To truly maximise our anaerobic/VO2 Max performance, we must maximise our aerobic threshold. This is where aerobic deficiency syndrome (ADS) comes in. A term introduced by Phil Maffetone in the 1980s, it simply refers to athletes having a low aerobic threshold in relation to their anaerobic threshold, predominantly caused by too much high intensity training. In short, if your aerobic threshold is more than 10% below your anaerobic threshold (in terms of pace per mile or heart rate), then you have ADS. ADS refers to an underdeveloped aerobic system and a lack of efficiency when using oxidation of fat for fuel, at higher paces/heart rates.
So to determine if you have ADS we need to do another thing a lot of runners regularly ignore, testing and assessing (and no, I don't mean a Park Run!). First we need to establish our AeT and our AnT.
AeT Test: To establish aerobic threshold we have a few options:
- Run for 30-60 mins at a speed where we can maintain a comfortable conversation with full sentences and no pauses. Take your average pace/heart rate and this will determine AeT.
- Run at a speed where you are breathing exclusively through your nose for 30-60 mins. Take average pace/heart rate to determine AeT.
- Run at Maximum Aerobic Function (MAF) heart rate. Your MAF is determined by subtracting your age from 180. If you've been training consistently for 2 years (without set backs such as injury), you should add 5 bpm. If you are recovering from a long lay-off period following injury, you should injury, you should subtract 5. This will give you a heart rate to run at which is just below aerobic threshold.
AnT Test: To establish anaerobic threshold we simply need to run a 30-60 mins time trial at a comfortably hard effort. A pace at which, if you were to go slightly quicker, would result in a reduction in speed. Typically it's your 10k pace (for those with a 10k of around 60 mins). Once your time trial is complete, take your average pace/heart rate to determine AnT.
Now that you've established both values we need to calculate whether they are within 10% of each other. This will determine if you have ADS. If the 2 figures are within 10%, you have a solid aerobic foundation! If not, in order to address the issue you should focus less on tempo runs, hill reps and sprints and focus more on base building running at your AeT pace with regular re-tests. I'd recommend re-testing once every 8-12 weeks.
One thing you need to understand is if you do have ADS, it is likely that your AeT pace will be very slow (perhaps even walking pace). Frustrating as it may seem to rectify this problem you need to be patient and continue to train at this pace. This will enable you to develop your ability to run faster aerobically. This is a tried and tested method to address ADS used by elite athletes. They typically spend 80-85% of their training at around AeT, which equates to upwards of 800 hours per year. So if it's good enough for them, it's good enough for us mere mortals!