Things aren't Always as they Seem

A bundle of skeletal muscle fibers is called a fascicle.  Scientists often look at small bundles of fibers to understand the entire muscle.  Understanding muscular differences between running and walking certainly is important to a coach.  Researchers recently examined the fascicle shortening velocity of bundles of fibers as subjects switched from a walking gait to running.

In walking and running our ankles operate in a spring like manner.  Our muscles contract isometrically, that is not changing their length upon landing, then we spring into action.  Tendon stretch and recoil yields what is deemed elastic strain energy.  Tendons are similar to steel springs that also store energy and return energy and once stretched propel us forward. 

In walking the muscle elicits isometric tension at an optimal muscle length, deviating minimally from this condition.  The tendon executes a stretch recoil cycle in each step we take. 

The movement of the foot that flexes the foot or toes downward toward the sole is called plantar flexion.  The gastrocnemius muscle is a plantar flexor of the foot.  When switching from walking to running the interaction of this muscle and it's tendon, the Achilles, is a topic of high interest.  How does this calf muscle go about producing greater force to increase speed? 

describe the imageThrough ultrasound imaging and motion analysis researchers studied the medial gastrocnemius muscle-tendon unit's transition from walking to running.  They found the shortening velocity of the fascicle increased with walking impairing the muscle from producing force.  When switching to running the fascicle velocity is reduced at the time of peak force.  Slowing the fascicle velocity actually increases peak and average muscle force and lowers the metabolic cost of running.

But really who would have thought you slow things down muscularly to move forward.

 

 jake

Four time All-Pro Jake Long  ....... Pendulum Vertical Chest Press

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