HES 3873: Principles of Personal Training Exam 1

Pennation Angle

The angle at which muscle fibers are offset from their line of pull. Increasing pennation packs a greater volume of muscle fibers into a given space

Unipennate Angle

Single set of fibers with the same line of pull

Bipennate

Two sets of fibers at different angles

Multipennate

Many sets of fibers acting at various angles

Tendons

Connect muscle to bone. Formed by inelastic collagen to withstand high tensile forces produced during muscle contraction.

Sagittal Plane Description

Divides body into left and right sides

Sagittal Plane Allowed Movements

Flexion, Extension, Hyperextension, Dorsiflexion, Plantarflexion

Sagittal Plane Example Exercises

Biceps curls, squat, sit-up, toe raise

Frontal Plane Description

Divides body into anterior (front) and posterior (back) halves

Frontal Plane Allowed Movements

Abduction, Adduction, Lateral Flexion, Elevation, Depression, Inversion, Eversion, Radial/Ulnar Deviation

Frontal Plane Example Exercises

Wide-grip shoulder press, side bend, standing abduction

Transverse Plane Description

Divides body into superior (upper) and inferior (lower) halves

Transverse Plane Allowed Movements

Left/Right Rotation, Medial/Lateral (Internal/External) Rotation, Supination, Pronation, Horizontal Abduction/Adduction

Transverse Plane Example Exercises

Dumbbell chest fly, seated torso machine, arm wrestle movement

Force

Mechanical action applied to a body that produces acceleration (𝐹 = 𝑚 × 𝑎)

Internal Force

Produced inside the body (muscles, tendons, ligaments)

External Force

Applied outside the body (gravity, friction, air resistance)

Newton’s First Law (Inertia)

A body remains at rest or in uniform motion unless acted upon by an external force

Newton’s Second Law (Acceleration)

Net force produces an acceleration proportional to the force (𝐹 = 𝑚 × 𝑎)

Newton’s Third Law (Action-Reaction)

Every action has an equal and opposite reaction (e.g., Ground Reaction Force during running).

Torque

Tendency of a force to cause rotation around an axis.

Moment Arm

Perpendicular distance from the fulcrum to the line of force action

Internal Moment Arm

Insertion point distance from joint center. A tendon inserting further away increases the internal moment arm and torque capacity, but decreases angular velocity per contraction unit.

1st Class

Fulcrum is between Applied Force (𝐹𝐴) and Resistance Force (𝐹𝑅). Mechanical advantage depends on relative moment arm lengths

2nd Class

𝐹𝑅 is located between the fulcrum and 𝐹𝐴. 𝐹𝐴 moment arm is always

longer (𝐹𝐴 > 𝐹𝑅), making force production mechanically advantageous (e.g., calf

raise). Rare in the human body.

3rd Class

𝐹𝐴 is located between the fulcrum and 𝐹𝑅. 𝐹𝑅 always has the mechanical advantage (𝐹𝑅 > 𝐹𝐴). Dominant lever system in the human body (e.g., biceps curl)

Hierarchical Structure

Whole Muscle → Fascicle → Muscle Fiber (cell) → Myofibrils → Myofilaments

Sarcomere

Functional contractile unit of skeletal muscle spanning Z-line to Z-line

Myosin (Thick Filament)

Features head, neck, and tail structures. Heads bind to and pull actin

Actin (Thin Filament)

Globular protein structure containing tropomyosin and troponin

Tropomyosin

Blocks myosin-binding sites on actin at rest

Troponin

Binds to calcium (Ca2+), causing a conformational shift in tropomyosin to reveal binding sites

Sliding Filament Mechanism

Neural activation causes calcium release → Calcium binds to troponin → Tropomyosin shifts → Myosin heads attach to actin (cross-bridge formation) → Power stroke pulls actin inward → Sarcomere shortens

Concentric

Muscle overcomes external load and shortens

Eccentric

External load exceeds muscle force, causing the muscle to lengthen while attempting to shorten

Isometric

Muscle force equals external load; no change in length

Delayed Onset Muscle Soreness (DOMS) Cause

Microscopic tears in muscle tissue and connective tissue sheaths (epimysium, perimysium, endomysium). Not caused by lactic acid accumulation.

Delayed Onset Muscle Soreness (DOMS) Treatment Options

Light exercise, massage, ice, ultrasound, supplementation

Motor Unit

Single motor neuron and all the muscle fibers it innervates. All fibers within a single motor unit share the same fiber type

Twitch Speed / Force Type I (Slow Oxidative) PPTX

Slow/ Low

Twitch Speed / Force Type IIa (Fast Oxidative-Glycolytic) PPTX

Fast/ Intermediate

Twitch Speed / Force Type IIx (Fast Glycolytic) PPTX

Fast/ High

Primary ATP Source Type I (Slow Oxidative) PPTX

Aerobic

Primary ATP Source Type IIa (Fast Oxidative- Glycolytic) PPTX

Combination

Primary ATP Source Type IIx (Fast Glycolytic) PPTX

Anaerobic (Glycolytic)

Mitochondria & Vasculature Type I (Slow Oxidative) PPTX

High/ Dense

Mitochondria & Vasculature Type IIa (Fast Oxidative- Glycolytic) PPTX

Intermediate

Mitochondria & Vasculature Type IIx (Fast Glycolytic) PPTX

Low

Fatigue Resistance Type I (Slow Oxidative) PPTX

High

Fatigue Resistance Type IIa (Fast Oxidative- Glycolytic) PPTX

Moderate

Fatigue Resistance Type IIx (Fast Glycolytic) PPTX

Low (Fast Fatigue)

Activation Threshold Type I (Slow Oxidative) PPTX

Low

Activation Threshold Type IIa (Fast Oxidative- Glycolytic) PPTX

Intermediate

Activation Threshold Type IIx (Fast Glycolytic) PPTX

High

Motor Unit Recruitment

Recruiting additional motor units

Rate Coding

Increasing firing frequency of active motor units. Small muscles rely more on rate coding; large muscles rely more on motor unit recruitment

Size Principle

Motor units are recruited in order of increasing size and activation threshold (Type I → Type IIa → Type IIx) depending on force demand

Muscle Spindles

Located within skeletal muscle. Sense rapid changes in muscle length (stretch) → trigger reflex contraction of agonist muscle to prevent overstretching

Golgi Tendon Organs (GTO)

Located at the musculotendinous junction. Sense excessive tension → inhibit agonist muscle contraction to prevent injury. Resistance training increases the GTO activation threshold.

Phosphagen System Primary Substrate

Creatine Phosphate (PCr)

Phosphagen System Oxygen Needed?

No (Anaerobic)

Phosphagen System Duration / Intensity

0–10 sec / High Intensity

Phosphagen System ATP Yield Rate

Extremely Fast

Phosphagen System Total Capacity

Very Low

Glycolytic System Primary Substrate

Glucose / Glycogen

Glycolytic System Oxygen Needed?

No (Anaerobic)

Glycolytic System Duration / Intensity

10 sec – 2 min / Moderate- High

Glycolytic System ATP Yield Rate

Fast

Glycolytic System Total Capacity

Moderate

Oxidative System Primary Substrate

Fats, Carbohydrates, Proteins

Oxidative System Oxygen Needed?

Yes (Aerobic)

Oxidative System Duration / Intensity

> 2 min / Rest & Low Intensity

Oxidative System ATP Yield Rate

Slow

Oxidative System Total Capacity

High (Very High for Fats)

Lactate Threshold (LT1)

Abrupt increase in blood lactate concentration above 2.0 mmol/L (50--60% VO2max in untrained, 70--80% in trained).

Onset of Blood Lactate Accumulation (OBLA / LT2)

Blood lactate reaches ≥ 4.0 mmol/L, reflecting large motor unit recruitment

Metabolic Fatigue

Fatigue is caused by accumulation of H+ ions (causing acidosis/lowered pH), not lactate itself. Elevated H+ inhibits myosin ATPase, reduces calcium release, and interferes with actin-myosin binding

Crossover Concept

Shift in fuel selection from fats to carbohydrates as exercise intensity increases

Oxygen Deficit

Lag in O2 intake at exercise onset, forcing reliance on anaerobic pathways (Phosphagen/Glycolytic)

EPOC (Excess Post-Exercise Oxygen Consumption)

Post-exercise elevation of O2 consumption to replenish PCr stores, clear lactate, restore blood/tissue oxygen levels, and

normalize body temperature and hormones

Growth Hormone (GH) Primary Gland

Anterior Pituitary

Growth Hormone (GH) Target Actions during Exercise

Stimulates IGF-1, protein synthesis, bone growth, mobilizes FFAs, spares plasma glucose

Growth Hormone (GH) Primary Stimulus

Exercise, stress, low blood glucose

Cortisol Primary Gland

Adrenal Cortex

Cortisol Target Actions during Exercise

Glucocorticoid; increases gluconeogenesis, breaks down proteins, mobilizes FFAs, blocks cellular glucose uptake

Cortisol Primary Stimulus

Heavy stress, high- intensity/prolonged exercise

Testosterone Primary Gland

Testes

Testosterone Target Actions during Exercise

Anabolic steroid; promotes muscle tissue building and androgenic characteristics

Testosterone Primary Stimulus

LH release, heavy resistance exercise

Insulin Primary Gland

Pancreas (𝛽-cells)

Insulin Target Actions during Exercise

Promotes storage of glucose, amino acids, and fats; decreases during exercise

Insulin Primary Stimulus

Elevated blood glucose

Glucagon Primary Gland

Pancreas (𝛼-cells)

Glucagon Target Actions during Exercise

Promotes mobilization of glucose from liver glycogen and FFAs; increases during exercise

Glucagon Primary Stimulus

Low blood glucose, elevated catecholamines

Epinephrine / Norepinephrine Primary Gland

Adrenal Medulla

Epinephrine / Norepinephrine Target Actions during Exercise

Fast-acting; stimulates liver and muscle glycogenolysis, mobilizes FFAs, increases heart rate

Epinephrine / Norepinephrine Primary Stimulus

Exercise intensity

Plasma glucose is preserved through four primary mechanisms controlled by hormones

1. Mobilization of glucose from liver glycogen stores.

2. Mobilization of FFAs from adipose tissue to spare blood glucose.

3. Gluconeogenesis in the liver using amino acids, lactate, and glycerol.

4. Blocking entry of glucose into non-active cells to force FFA usage.

Muscle Glycogen Control

Muscle glycogen depletion accelerates during high-intensity exercise, driven by Epinephrine