Pacing & Fatigue

Dennis-Kimetto

This is a crash course in what is referred to as the Central Governor Model of Fatigue (Noakes) or Anticipatory Regulation Model (Tucker)

I had been thinking of writing this for a few days but after heading to a 5km fun run with my fiancé early Sunday morning I thought I would get cracking.

Have you ever wondered why athletes speed up at the end of a long distance race? How can an athlete, who is largely extremely fatigued, find an energy/muscular reserve at the culmination of a 10, 21.1 or 42.2km effort and run at a faster pace than they have been during the majority of the race? Most people will just say, “oh, they just paced themselves”; but the mechanisms involved in this pacing strategy involve more than just running at a specified ‘race pace’.

The Anticipatory Regulation Model (see Ross Tucker) suggests that at the beginning of the race the subconscious brain performs calculations to the metabolic cost of the exercise bout, race or game. This calculation selects the optimum pacing strategy for the duration of exercise, to therefore complete the task in the most efficient state while still maintaining homeostasis. Now of course, the pacing strategy is based upon prior race experience and training but it is also suggested that the running velocity is subconsciously set, upon knowledge of the predetermined end point or finish line.

Although not a distance athlete, I believe in the science and research of this model and I feel that even without the latest Garmin watch, athlete’s generally know how far they can ‘redline’ and still get to the finishline. In my opinion, it is definitely the brain, central governor, reducing motor unit recruitment and reducing workrate, rather than fatigue at the muscular level (peripheral fatigue e.g. lactate) sending the signal to the brain. Once the athlete knows the finish-line is within reach, the governor is released and the athlete can increase their pace during the last kilometre. There is little chance of further physiological damage to the body and therefore the motor unit recruitment is increased, providing an increase in speed.

As mentioned, prior experience in the event and training will most likely play the major role in ‘pacing’. However, my thoughts on how to create a new and varied experience at the subconscious level include:

  • Running reps for maximum distance in a set time period (therefore eliminating a predetermined finish-point)
  • Running reps of less-common distances so athlete’s do not have a time bias to pace for that distance
  • Utilising fartlek training to create a random nature of time and distance for the exercise bout

In a team sport setting, the same principles can be applied to a practice session by asking athletes to compete in various drills for an unknown time period. Once you provide them with the duration for the drill, they subconsciously regulate their performance, regardless if they believe they are going 100%.

A pretty long-winded way to explain pacing but it is more than just lactic acid slowing athletes down.

 

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