A run for the times: Circuit runs

One run bound to become popular in the coming two weeks is the ‘Circuit run’. I originally adopted this phrase for a run described to me by Keith Livingstone, author of ‘Healthy Intelligent Training’. A run being used by his ‘HIT Squad’ of young talented high school runners in New Zealand.

As the name implies it requires a circuit. With the Irish population currently advised to exercise within a 2 km radius of their home, a circuitous route is a natural choice. Using the ‘Circuit run’ format can spice up the experience. With guidelines also stating to keep exercise ‘brief’, the easiest way to keep training load high is to increase the intensity and do less easy running during this period. Normally this is a recipe for disaster but if, as we all hope, this restriction will only last 2 weeks at most, it can serve as a ‘special block’ (a period focused on something specific after which extra recovery is taken to rebalance). So if you increase your intensity over the coming two weeks, you need to balance that out with more than usual easy running in the week after that.

The circuit run consists of running one circuit at one pace and the second circuit at a second pace (or intensity / HR). The basic format is a steady run where you alternate between ‘steady’ intensities and ‘easy’ intensities. This is a way to build up time at paces that for most will range from 10k to marathon pace or in the heart rate zone 3 (subthreshold to threshold running). For specific instructions use the workout description I wrote years ago: click here

But you do not have to limit yourself to this format. Here are two variations that provide a different stimulus:

 

Alternations

Steve Magness coined this term (I believe) to describe a type of workout popularised by numerous coaches in different terms (Renato Canova and Peter Thompson among them). In alternations there is no true ‘rest interval’ (that’s why they are not called ‘intervals’) and instead you simply ‘alternate’ two paces or intensities. For this to work best one intensity should be high enough to start accumulating some lactate in your system. This usually requires faster than 10 km pace and, generally, faster than 3 km pace if the circuit or fast segment is quite short. You alternate this fast – lactate accumulating – pace or intensity with a more moderate intensity but NOT WITH EASY.

Not a lot of runners and coaches are aware that easy pace is not necessarily the best intensity to recover from a hard effort. This is because of something called ‘lactate clearance’ and the ‘lactate shuttle’. Simply put your body can reuse lactate and it can become increasingly good at this ‘clearance’ and ‘reuse’. The maximum ‘clearance rate’ (think: how quickly your aerobic energy system can hoover up and reuse the lactate floating around) is not at easy paces but rather usually occurs somewhere between marathon and 10 k pace. The pace needs only be slow enough that no more lactate is accumulated and the body starts to ‘lower the level’. A lab test can find these paces for certain (I’ll post more on this in a month’s time) but without that you have to feel your way along.

When you alternate a ‘hard’ (lactate accumulating) pace with a ‘moderate’ (lactate ‘eating’ pace), you teach your body many useful things including:

  • How to re-use lactate efficiently as an extra fuel source
  • How to alternate between paces relevant to your race just as you may do when surging or changing pace in a race situation
  • Recovering at a ‘faster’ pace as you will have to do in races

This workout can give you the physiological benefits of running at 10 mile or 5 km pace while at the same time boosting your ability to recycle lactate. For that reason it does not have to be overly long. The only thing to watch is the length of the fast segment. If your circuit is very long, you cannot run at 3k or 5k pace without accumulating too much lactate. Alternating 2 km at 5k pace with 2 km of marathon pace will be too demanding for most runners – so this workout works best on a shorter circuit OR if you do part of your circuit at the faster pace (for instance ¼ of the circuit at 3 k pace and ¾ of the circuit at marathon effort).

Economy intervals

This workout was based on the work of Shannon Grady (author of the ‘Lactate Revolution’) and can be done on circuits of 200m or shorter. You begin by running the short circuit at 800m to 5 km pace (depending on your goals and ability – best pick a pace you plan to use extensively later in your training) and then do several circuits (four to five) at easy pace until you are fully recovered. This session prepares your body to be economical and efficient at fast paces normally reserved for hard repetition sessions. But because of the very short segment of faster running and the very long recovery, you will have little to no build-up of lactate and metabolic waste products in your body. This allows you to prepare your body for these paces without needing long recovery or turning the workout into a heavy anaerobic load which, when done in excess, overloads the body’s ‘fight or flight’ response (overstimulates your sympathetic nervous system) with deleterious consequences for your health.

In reality, this session is just a type of ‘short to medium strides’ under a different name – that means controlled fast short repetitions followed by very long easy running intervals. An example could be 6x 200m @ 3k pace with 800m easy jog in between each (a 6 km run and then you would want to add warm-up or cooldown) or the classical 10x 100m @ 1500m effort with 400m jog recovery.

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