Why you don’t do anaerobic exercise during the aerobic phase

“No anaerobic training during certain parts of the year?” This may seem heretical to many but it is a firm principle of the Lydiard system which cannot be violated without giving away some of the benefits of the system. Since many will contest this point, I found it essential that this article be among the first we publish on ChampionsEverywhere.

Dr Phil Maffetone summarises the three main negative effects of performing extended anaerobic training while attempting to build to your maximal aerobic fitness:

  • Anaerobic training can decrease the number of aerobic muscle fibres, sometimes significantly. This can happen in just a few short weeks of higher heart rate training.
  • The lactic acid produced during anaerobic training may inhibit the aerobic muscle enzymes necessary for building an aerobic base.
  • Anaerobic training raises your respiratory quotient. This means the percentage of energy derived from sugar increases and fat burning decreases. In time, this may force more anaerobic metabolism and less aerobic function.

Dr Keith Livingstone, author of “Healthy Intelligent Training”, the official training manual of the Lydiard Foundation, further delves into the topic and explains the exact science why you will see detrimental effects from mixing your aerobic phase traning with anaerobic training.

Lactic acid – the problem?

Lactic acid traditionally get’s the blame for the burning sensation you feel in your muscles (we debunk this and more in Myths: lactic acid causes fatigue) but in reality it seems caused by a build-up of acidosis (lowering of the pH) in your working muscles. Hydrogen ions and other waste products are the likely cause of this acidosis although it has not been confirmed  if the burning sensation comes from that source. We do know it is not lactic acid for as Jason Karp noted in his talk in Boulder during the Lydiard Seminar: “I have never burned myself on blood samples taken from individuals doing anaerobic exercise.”

Acidosis – the real problem

This acidosis starts a cascade of unwelcome events within your body including the sabotaging of the aerobic enzyme system on which your base fitness is built. This decreases your endurance capacity and it can take 24 to 96 hours for your system to settle back to normal but recovery can take longer. Buffering training with aerobic exercise can help reduce this effect but it should be easy to see why repeated anaerobic training (intervals, tempos etc.) with low reliance on aerobic exercise will very quickly whittle away the overall fitness of an athlete.

I need to mention one of the physiological problems of scheduling hard anaerobic workouts for prolonged periods…eventually – especially if racing is added to hard interval training-there is a great risk that blood pH may not return to normal. When that happens, it can upset your ability to get nutrients out of food, upset the central nervous system, and manifest itself in a loss of performance and interest in running.In the end, excessive anaerobic training pulls down your VO2 max, and you can’t even run the slow stuff very well.” – Ron Daws, Running Your Best

During the aerobic phase you are trying to build the fitness foundation on which your entire season will be built. So it is undesirable to jeopardise this in any way. Any anaerobic exercise done will temporarily reduce your aerobic capacity and hamper you efforts. In addition, Barry Magee, the 1960 Olympic bronze winner and one of “Arthur’s boys”, has stated that evidence today shows that anaerobic metabolism can destroy newly formed capillary beds. This is essentially the same as building five nice new roads one day and then destroying two of them the next day: not the ideal way to build the highest possible performance peak.

One way this harmful effect manifests is damage to the aerobic enzymes as coach Greg McMillan explains:

“I’ll fall back to Lydiard who learned that during aerobic base building it is not good to ‘pull down the ph’ as he stated it. The reason is that a large build up of lactic acid (lowering the ph in the cell) can destroy the aerobic enzymes – not what you want during this period of training. We also know from Lydiard that heavy anaerobic training cannot be sustained for long periods of time so it’s better to only insert it at appropriate times.” – Greg McMillan, McMillan Running

Is anaerobic always bad?

While we do need anaerobic training at the right time in our training, Livingstone points out how not to use it:

“Funnily enough, we need this sort of training in sparing doses to fully realise our potential in the middle distances. What we don’t need is to bomb this energy system day in, day out, at a time of year when we should be “accumulating” aerobic fitness and improving sprint potential.” – Keith Livingstone (Healthy Intelligent Training)

Studies done in 1996 proved, however, that the aerobic contribution to even middle-distance races is much greater than originally anticipated, as high as 65-73% for 800m runners and 80-86% for 1500m runners. So while anaerobic training is necessary it provides a very minor part of the energy across all middle-distance and long-distance events and with the increased risk of this training should be moderated as much as possible and used only in the periods close to racing season when it is needed the most.

What about sprints?

It is important to note Livingstone’s last point that you can do sprints and strides without any ill effects during the aerobic training phase. While running at these speeds is also done anaerobically, they are so short that they utilise another energy system called the “alactic” (e.g. “without lactate”) system. Done with plenty of recovery and good technique this type of exercise is both safe and beneficial.

Sympathetic overtraining

When you do not heed this practice and pursue anaerobic training year-round, you will, at best, create a performance plateau as your aerobic and anaerobic energy systems “eat into each other”. It is a bit like constantly taking a few steps forward only to take a few more backwards. You won’t be going very far in the end.

When anaerobic training is conducted regularly over extended periods, you put yourself at great risk of form of overtraining known as the “sympathetic type” which is caused by an overload of your adrenal gland. A full walk through of this effect requires an article in it’s own right and I recommend you read John Berardi’s article “What You Don’t Know About Overtraining” or, for the scientific minds, purchase the excellent “Enhancing Recovery – preventing underperformance in athletes”.

Final words on the matter

I hope we have you convinced at this stage but if not perhaps a final quote from Arthur Lydiard on the matter will seek to further persuade you:

“Anaerobic training is something we have to do if we intend to race well but, at the same time, we must always keep in mind that if we overdo it we lose our most essential asset, the very thing we have been building, our good condition, which determines our performance level. So, all the time you are building your capacity to exercise anaerobically, jealously guard your good condition or the whole purpose of the programme is defeated.” (Arthur Lydiard, Running with Lydiard)

Lydiard observed that runners who peaked early in the season by employing anaerobic exercise would lose their form completely halfway through the season. So treat anaerobic training with respect: it is a precision tool to be employed close to the season and in measured doses. It has no place in the early stages of Winter training while building your aerobic capacity.

Also published on Medium.

The following two tabs change content below.


Director and coach at Borg Coaching Services
Rene Borg is the head coach of Glendalough AC and a passionate runner competing over all distances and terrains.

Latest posts by René (see all)