Exercise Physiology and Neuromuscular Control Review

Vocabulary flashcards covering neuromuscular concepts, reflex arcs, autonomic neurotransmitters, and endocrine regulation of metabolism during exercise.

Cerebellum and basal ganglia

Brain centers involved in motor control; the cerebellum assists in correcting errors during fast movements, while the basal ganglia is involved in initiating movement and is affected by low dopamine (as in parkinston’s disease).

Size principle

A neuromuscular rule that recruits motor units from small to large to force the muscle units AS FORCE DEMAND increases.

Rate coding

The mechanism allowing muscle force to continue to increase via higher flier frequency after recuitment of all motor units is complete.

Innervation ratio (Tibialis anterior example)

The ratio of muscle fibers supplied per motor neuron (averaging $600$ fibers per motor neuron in the tibialis anterior with its $150$ motor neutrons), resulting in $15{,}000$ active fibers when $25$ motor units are recruited.

Muscle spindle

The receptor that detects rapid stretch and initiates the reflex arc when a clinician taps the patellar tendon, prompting the lower leg to kick forward.

Sympathetic cardiac pathway

The autonomic signaling route from the spinal cord to the heart wherein the preganglionic sympathetic neuron releases ACh and the postganglionic sympathetic neuron releases NE, causing heart rate to increase.

Sweat glands (Sympathetic innervation)

Structures that serve as a sympathetic exception because they recieve ACh.

Plasma FFA reduction factors

Factors reducing free fatty acid availability during heavy exercise despite elevated lipolytic hormones: lactate promotion of FFA re-esterification, $H^+$ inhibition of HSL, and reduced adipose blood flow.

Intracellular control of glycogenolysis

The principle demonstrated by one-leg exercise showing that glycogenolysis is primarily driven by local, intracellular factors within contracting muscle rather than systemic hormonal control alone, as glycogen depletes mainly in the working leg despite epinephrine reaching both legs.

Intensity-dependent Cortisol and GH response

Endocrine responses showing that at $40\text{--} VO_2\text{ max}$, cortisol likely decreases while GH exhibits a minimal or very modest increase; at $80\text{--} VO_2\text{ max}$, both cortisol and GH elevate significantly.

Lactate inhibition of HSL

The primary mechanism contributing most to decreased free fatty acid (FFA) utilization during intense exercise despite elevated mobilization hormones.

Propranolol β-adrenergic blockade

The pharmacological blockade of β-adrenergic receptors that does not completely prevent muscle glycogen breakdown during exercise, disproving that plasma epinephrine is the sole initiator of glycogenolysis.

Fast-acting hormones

The pair of hormones classified as fast-acting in the context of exercise: Epinephrine and Norepinephrine.

Blood glucose maintenance during exercise

The endocrine combination of decreased insulin and increased glucagon that operates during a $30$-minute run at $70\text{--} VO_2\text{max}$ to maintain circulating blood glucose.

Post-endurance training catecholamine response

The physiological response following a $12$-week endurance training program where plasma epinephrine (E) and norepinephrine (NE) levels decrease at the same absolute running speed because relative intensity ($\text{\%}VO_2\text{max}$) is lower.

Cortisol kinetics below threshold

The metabolic condition during low-intensity exercise where plasma cortisol concentration remains unchanged or decreases primarily because cortisol removal exceeds cortisol secretion.

Dual control of muscle glycogen breakdown

The regulatory system governing muscle glycogenolysis during exercise primarily controlled by Epinephrine–cyclic AMP and $Ca^{2+}$–calmodulin.