The Central Governor Theory
Central Governor Theory? Sounds a little dry, eh? I know, I know, but I think
there is a lot to it. It is a theory or a model so it can’t be proven, but it holds up to
current training theory and provides a good explanation for most ideas that go
unexplained by other models.
During long efforts, generally over 2-3 hours, our current effort can’t be
maintained, and there is an inevitable drop off in our pace, even when
calories and hydration are adequately ingested. Why?
You guessed it…the Central Governor Theory. The theory is basically that
maximum exercise capacity is a process coordinated subconsciously by the brain,
limited by the maximum coronary blood flow to supply oxygen to the heart and
regulated to prevent heart damage during maximal exercise. (Noakes, 2001) The
way it works is that we have a series of devices within the brain that monitor
different vitals in the exercising body.
Among these:
glycostat = monitors muscle and liver glycogen and blood glucose levels.
cardiostat = keeps an eye on heart rate, blood pressure, coronary blood flow,
stroke volume and just about every other conceivable statistic necessary to
prevent damage to the heart.
So let’s say you are going to run a marathon. Towards the end of the run your
pace will inevitably drop off even if you continue religiously with calorie ingestion
and hydration. Our bodies are very efficient (which is why we store away fat so
easily---the body adds to the “savings account” in case of emergency period
without food) and very protective (which is why it is difficult to bear weight on a
surgically repaired leg----our bodies being unfamiliar with surgery, temporarily
shut muscles down in order to protect the “injured” leg, even when weight-bearing
is exactly what is required to heal that leg). In much the same way when we run
at an intensity or duration that nears our longest or most intense training run, the
body, being in unfamiliar territory has a main goal of protecting the heart. If
exercise were allowed to proceed unregulated until all ATP was used up then
muscle rigor would set in—our muscles would freeze or lock up. If this occurred
in the heart muscle than a maximal effort would end in death…not a very wise
idea.
There are a number of chemicals and compounds that make exercise possible.
ATP, enzymes like myosin ATPase, and calcium among others. We will forgo the
complexity of trying to keep track of all of them and focus on ATP, since it is your
body’s energy currency. Since letting ATP stores deplete down to zero is not an
option, the central nervous system takes some precautionary measures. To limit
the depletion of ATP, the brain limits the number of muscle fibers recruited during
each contraction.
The fewer the number of muscle fibers being used ==> the less ATP used ==>
and the more ATP is spared to prevent any possibility of damage to the heart.
However, what this translates into is a weaker muscle contraction. Weaker
muscle contractions in the leg during running results in less power transfer for
each stride. Each foot-strike will stay longer on the ground, our cadence will
decrease and our pace slows. EMG studies (measurement of the amount of
muscle activity) on cyclists who have completed a 100km time trial and then are
asked to perform maximal sprint efforts, prove that fewer muscle fibers are
recruited at the end of an extended exercise period. (St. Clair Gibson et al. 2001)
Having shown that the Central Governor Theory is a viable one, researchers are
now turning to how to convince the Central Nervous System to continue muscle
recruitment at a high level at the end of an exercise session. My basic theories
on how to do this are:
1. Train frequently at race pace and occasionally faster. As with any
training adaptation, our body will inevitably become more efficient. Running
faster than race pace will produce an adaptation that enables you to run longer
at race pace. This translates from fast to slow, but not slow to fast. I.E. running
slow for long periods of time will never make you more efficient at faster paces.
2. Train occasionally at race distance or greater. When we train at long
distances, especially those longer than our race distance (for races under 40km)
increasing the likelihood that we build a tolerance for these distances and that
our bodies “get used” to them. If the body adapts and the CNS deems the
distance more routine, then the it may allow greater muscle recruitment toward
the end of a run. In races above 40km, special care should be taken to avoid
over-training. Especially for the novice it is unreasonable to run 40km or more
even once in the course of training for a race.
3. Run “Progressively”. On longer runs the tendency, as explained
earlier, is to have your running pace drop off. We can force the issue on our
muscles, but more importantly, on our CNS by implementing tempo or sprint
efforts at the end of a run to stimulate the motor centers in the brain to continue
sending signals at high levels to a large number of motor units. Progressive runs
have been a staple among Kenyan runners for years. They exist in many
incarnations; gradual increases in pace spaced predictably and tolerably
throughout a run, to all out sprints of 1-10 minutes at the end of a run.
Hope this helps.