APEX Clinic: Muscle Function

RideEndurance.blogspot.com
Monday, August 17, 2009
APEX Clinic: Muscle Function

The first lecture at the clinic was on muscle function, organized by Ann Stuart, DVM. Ann has been involved in endurance riding since the early 1990s as both rider and veterinarian, and has served on team veterinary staff for international endurance rides multiple times. Most of Ann's lecture was devoted to understanding muscle physiology and understanding its relation to the sport of endurance. A lot of it was review from high school and college anatomy and physiology courses, but who remembers all of it? A review is always helpful. The start of the lecture focused on the anatomy of muscle and understanding how a muscle functions. Some highlights:

* We all know aerobic work is more efficient than anaerobic work. I had never made the connection to its efficiency at the cellular level. Anaerobic respiration is the process of turning glucose into pyruvate, producing only 2 ATP (energy molecules) and lactic acid as a by product. Aerobic respiration is the Krebs Cycle (Citric Acid Cycle), which in turn produces 34 ATP molecules! That's 17 times the amount of energy!
* Even relaxation requires energy in the form of ATP. Thus, in order for muscles to relax after hard work, they still need energy. Cramping occurs when there isn't enough energy (ATP) available for the muscles to relax.
* Aerobic work by muscles is supported by saltatory conduction - a process which allows sodium ions to jump the myelin sheaths surround the nerve axon, thus speeding up the reaction.

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