Untitled Flashcards Set

📚 Study Guide: Chapter 4 – Hormonal Control During Exercise

1️⃣ Endocrine System Overview

✅ Endocrine System = Chemical Communication System
✅ Works slower than the nervous system but has longer-lasting effects
✅ Maintains homeostasis by regulating cells & organs using hormones

2️⃣ Types of Hormone Signaling

🔹 Autocrine – Acts on the same cell that produced it
🔹 Paracrine – Acts on nearby cells
🔹 Endocrine – Travels through blood to reach distant cells

3️⃣ Types of Hormones

✅ Fat-Soluble (Steroid) Hormones (Made from cholesterol)

• Require carrier proteins to travel in blood

• Pass through the cell membrane & bind to intracellular receptors

• Examples: Testosterone, Estrogen, Cortisol, Aldosterone

✅ Water-Soluble (Non-Steroid) Hormones (Proteins, Peptides, Amines)

• Bind to receptors on the plasma membrane (Cannot pass through)

• Use second messengers to activate signals inside the cell

• Examples: Epinephrine, Norepinephrine, Insulin, Growth Hormone

4️⃣ Hormone Action Mechanisms

🧬 Steroid Hormones (Fat-Soluble) → Directly Influence DNA

1. Hormone diffuses into the cell

2. Binds to intracellular receptor

3. Activates DNA transcription → Forms mRNA

4. mRNA directs protein synthesis (e.g., actin & myosin for muscle growth)

🔁 Non-Steroid Hormones (Water-Soluble) → Use Second Messengers

1. Hormone binds to membrane receptor

2. Activates a second messenger (cAMP, Ca²⁺, etc.)

3. Triggers cellular responses

5️⃣ Factors Affecting Hormone Effects

📌 Hormone Effect Depends On:
✅ Concentration released (how much hormone is in the blood)
✅ Transport (how well it reaches the target organ)
✅ Receptor number (more receptors = stronger effect)
✅ Sensitivity of receptors (regulated through upregulation/downregulation)

🔺 Upregulation – More receptors added to increase sensitivity (happens when hormone levels are low)
🔻 Downregulation – Fewer receptors to reduce sensitivity (happens when hormone levels are high)

6️⃣ Hormonal Regulation of Metabolism During Exercise

Key Endocrine Glands Involved:
🏋‍♂️ Anterior Pituitary – Growth hormone (GH)
🔥 Thyroid – T3 & T4 (metabolism boost)
⚡ Adrenal Glands – Epinephrine, Norepinephrine, Cortisol
🍽 Pancreas – Insulin (stores glucose), Glucagon (releases glucose)

7️⃣ Hormones & Metabolism During Exercise

8️⃣ Fluid & Electrolyte Balance During Exercise

🏃‍♂ During exercise, plasma volume decreases due to sweating
⚠ Hormones that regulate fluid balance:
✅ ADH (Antidiuretic Hormone) → Increases water reabsorption in kidneys
✅ Aldosterone → Increases sodium & water retention to maintain blood pressure

📌 Study Questions:

1️⃣ What is the difference between the endocrine system and nervous system?
2️⃣ What are the two types of hormones, and how do they act differently?
3️⃣ How does testosterone influence protein synthesis?
4️⃣ What factors determine how effective a hormone is?
5️⃣ What happens to insulin levels during exercise, and why?
6️⃣ How do epinephrine & norepinephrine affect metabolism during exercise?
7️⃣ What role does ADH play in maintaining hydration during exercise?

1️⃣ The Endocrine System & Its Role in Exercise

What is the Endocrine System?

• A chemical communication system that works alongside the nervous system to regulate body functions.

• Uses hormones (chemical messengers) to control metabolism, fluid balance, growth, and stress responses.

• Acts slower than the nervous system, but effects last longer.

Endocrine vs. Nervous System

2️⃣ Types of Hormone Signaling

1. Autocrine Signaling – Hormone acts on the same cell that produced it.

   • Example: Muscle fibers release IGF-1, which stimulates their own growth.

2. Paracrine Signaling – Hormone acts on nearby cells without entering the bloodstream.

   • Example: Inflammation response where cells release cytokines that affect neighboring cells.

3. Endocrine Signaling – Hormone is released into the bloodstream and acts on distant cells.

   • Example: Insulin from the pancreas travels through the blood to regulate glucose levels.

3️⃣ Types of Hormones & Their Mechanisms

1. Fat-Soluble (Steroid) Hormones

• Derived from cholesterol.

• Need a carrier protein for transport in blood.

• Pass through the cell membrane and bind to intracellular receptors (cytoplasm or nucleus).

• Directly influence gene transcription → Increase protein synthesis.

🔹 Examples of Fat-Soluble Hormones:
✅ Testosterone – Increases muscle growth.
✅ Estrogen – Regulates female reproductive function.
✅ Cortisol – Helps with stress response and metabolism.
✅ Aldosterone – Regulates sodium and water balance.

2. Water-Soluble (Non-Steroid) Hormones

• Proteins, peptides, and amines.

• Cannot pass through the cell membrane.

• Bind to membrane receptors and use second messengers (cAMP, Ca²⁺, etc.) to send signals inside the cell.

🔹 Examples of Water-Soluble Hormones:
✅ Epinephrine & Norepinephrine – Fight-or-flight response.
✅ Insulin – Lowers blood sugar.
✅ Glucagon – Raises blood sugar.
✅ Growth Hormone (GH) – Increases muscle growth and fat metabolism.

4️⃣ How Hormones Work: Signal Transduction Pathways

Steroid Hormone (Fat-Soluble) Mechanism

1️⃣ Hormone diffuses into the cell.
2️⃣ Binds to an intracellular receptor in the cytoplasm or nucleus.
3️⃣ Hormone-receptor complex activates DNA transcription.
4️⃣ mRNA is formed and directs protein synthesis.

Non-Steroid Hormone (Water-Soluble) Mechanism

1️⃣ Hormone binds to a receptor on the cell membrane.
2️⃣ Activates a second messenger system (cAMP, Ca²⁺, etc.).
3️⃣ Triggers enzymes and cellular responses.

5️⃣ Factors That Influence Hormone Effects

Hormonal response depends on:

1. Concentration Released – More hormone = stronger effect.

2. Transport in the Blood – Steroid hormones need carrier proteins.

3. Receptor Number on Target Cells – More receptors = greater response.

4. Sensitivity of Receptors – Can be upregulated (increased) or downregulated (decreased).

🔺 Upregulation – More receptors appear in response to low hormone levels (increases sensitivity).
🔻 Downregulation – Fewer receptors appear in response to high hormone levels (reduces sensitivity).

6️⃣ Hormonal Regulation of Metabolism During Exercise

Endocrine Glands Involved in Exercise Metabolism

🏋‍♂️ Anterior Pituitary – Releases growth hormone (GH) → Promotes fat metabolism.
🔥 Thyroid Gland – Releases T3 & T4 → Increases metabolism & energy production.
⚡ Adrenal Glands – Release epinephrine, norepinephrine, & cortisol → Increase energy availability.
🍽 Pancreas – Releases insulin & glucagon → Regulate blood glucose levels.

Hormonal Response to Exercise

7️⃣ Hormonal Regulation of Fluid & Electrolyte Balance During Exercise

🏃‍♂ During exercise, plasma volume decreases due to sweating.
⚠ Hormones that regulate fluid balance:
✅ ADH (Antidiuretic Hormone) → Increases water reabsorption in kidneys.
✅ Aldosterone → Increases sodium & water retention to maintain blood pressure.

📌 Study Questions:

1️⃣ What is the primary difference between steroid and non-steroid hormones?
2️⃣ How does the endocrine system regulate metabolism during exercise?
3️⃣ What are the key hormones involved in fat metabolism?
4️⃣ Why does insulin decrease during exercise, and what takes its place?
5️⃣ How do epinephrine & norepinephrine help with exercise performance?
6️⃣ What role does cortisol play in prolonged exercise?
7️⃣ How does aldosterone help maintain blood volume during exercise?

📚 Study Guide: Chapter 5 – Energy Expenditure & Fatigue

1️⃣ Energy Expenditure Overview

Why do we measure energy expenditure?

• To determine caloric needs for exercise, weight loss, or muscle gain.

• Helps understand performance, endurance, and fatigue.

Total Energy Expenditure Components

2️⃣ Measuring Energy Expenditure

1. Direct Calorimetry (Measures Heat Production)

✅ Pros:

• Accurate over time

• Good for measuring resting metabolism

❌ Cons:

• Expensive & slow

• Heat from exercise equipment affects accuracy

• Sweating creates measurement errors

2. Indirect Calorimetry (Measures Gas Exchange)

✅ Estimates energy expenditure by analyzing O₂ used & CO₂ produced.
✅ Only accurate for steady-state exercise (Why? Because anaerobic metabolism affects CO₂ levels).

🔹 Key Measurements in Indirect Calorimetry:

• V̇O₂ = Oxygen consumption per minute

• V̇CO₂ = Carbon dioxide production per minute

• Ve = Ventilation per minute

3️⃣ Respiratory Exchange Ratio (RER)

What is RER?

• RER = V̇CO₂ / V̇O₂

• Determines which fuel source (carbs or fats) the body is using.

RER Limitations

❌ CO₂ production may not equal CO₂ exhalation (e.g., during intense exercise or gluconeogenesis).
❌ Protein metabolism is not accounted for in RER calculations.
❌ Lactate buildup can cause RER >1.0 due to excess CO₂ exhalation.

4️⃣ Heart Rate Monitoring for Energy Estimation

• Estimates V̇O₂ based on heart rate.

• Useful for submaximal exercise, but has error rates.

🔹 Limitations of Heart Rate Monitoring:
❌ Only works for aerobic metabolism.
❌ Affected by temperature, fitness level, upper-body vs. lower-body exercise.

5️⃣ Energy Expenditure During Exercise

Walking vs. Running Energy Cost

• Metabolic Equivalent (MET):

  • 1 MET = 3.5 ml O₂/kg/min (resting metabolic rate).

  • Exercise energy cost = resting MET + additional METs based on activity.

Cycling Energy Cost

• Depends on resistance, cadence, wheel size, body weight, and bike weight.

• Power output measured in kg/m/min.

6️⃣ Energy Expenditure at Rest (Basal & Resting Metabolic Rate)

🔹 Total Daily Energy Expenditure (TDEE) = RMR + daily activities + exercise.

💡 Elite athletes can burn ~10,000 kcal/day!

7️⃣ V̇O₂ and Energy Expenditure

What is V̇O₂?

• V̇O₂ = Cardiac Output (HR × SV) × a-vO₂ difference

• V̇O₂ max = Maximum oxygen uptake during intense exercise (best measure of aerobic fitness).

🔹 Factors affecting V̇O₂ max:
✅ Heart function (HR, SV, Cardiac Output)
✅ Muscle efficiency (O₂ utilization in mitochondria)
✅ Training adaptations (plateaus after 8-12 weeks of training).

8️⃣ Energy Use in Maximal & Anaerobic Exercise

Oxygen Deficit & EPOC (Excess Post-Exercise Oxygen Consumption)

1️⃣ O₂ deficit – Early in exercise, O₂ demand > O₂ consumed → Body uses anaerobic metabolism.
2️⃣ EPOC – After exercise, O₂ consumption stays elevated to:

• Replenish ATP & PCr stores.

• Convert lactate back to glycogen.

• Restore hemoglobin & myoglobin O₂ levels.

9️⃣ Lactate Threshold & Fatigue

What is Lactate Threshold?

• Point at which blood lactate levels rise rapidly (~2 mmol/L).

• Lactate production > lactate clearance.

• Good predictor of endurance performance.

🔹 Factors Affecting Lactate Threshold:
✅ Training – Increases lactate clearance & tolerance.
✅ Muscle fiber type – More Type I fibers improve endurance.

🔟 Economy of Effort

• More trained athletes use less energy at a given pace (better efficiency).

• Factors influencing economy:
  ✅ Experience/practice → Better movement patterns.
  ✅ Type of activity (running, swimming, cycling).
  ✅ Muscle fiber recruitment efficiency.

🔥 Characteristics of Successful Endurance Athletes

✔ High V̇O₂ max
✔ High lactate threshold
✔ High movement economy
✔ High percentage of Type I muscle fibers

📌 Study Questions

1️⃣ What are the three main components of total energy expenditure?
2️⃣ What is the difference between direct and indirect calorimetry?
3️⃣ What does RER tell us about fuel usage?
4️⃣ Why does lactate accumulation lead to fatigue?
5️⃣ What is oxygen deficit, and how does EPOC help recovery?
6️⃣ How does training improve energy efficiency and endurance?
7️⃣ Why do elite endurance athletes have high lactate thresholds?

1️⃣ Introduction to Energy Expenditure

Energy expenditure refers to how the body uses energy to perform work, including resting metabolism, physical activity, and recovery processes. Understanding energy metabolism helps in training, performance optimization, and fatigue prevention.

Components of Total Energy Expenditure

1. Basal Metabolic Rate (BMR) – Energy required for basic life functions at rest.

   • Measured in a thermoneutral environment after 8+ hours of sleep & fasting.

   • Influenced by age, body size, hormones, temperature, and stress.

2. Resting Metabolic Rate (RMR) – Similar to BMR but slightly higher due to minor daily movements.

3. Thermic Effect of Food (TEF) – Energy used to digest, absorb, and process food (~10% of daily energy use).

4. Physical Activity Energy Expenditure – Energy burned from exercise and daily activities (~15-30% of total).

💡 Elite athletes can burn up to 10,000 kcal/day!

2️⃣ Measuring Energy Expenditure

1. Direct Calorimetry (Heat Production Measurement)

✅ Pros:

• Accurate over time

• Measures total heat production

❌ Cons:

• Expensive & slow

• Sweat affects measurements

• Not practical for exercise testing

2. Indirect Calorimetry (Gas Exchange Measurement)

✅ Measures oxygen (O₂) consumption and carbon dioxide (CO₂) production to estimate ATP production.
✅ Only accurate during steady-state exercise.

🔹 Key Measurements in Indirect Calorimetry:

• V̇O₂ = Oxygen consumption per minute

• V̇CO₂ = Carbon dioxide production per minute

• Ve = Ventilation per minute

🔹 Equation:

Energy Expenditure=V˙O₂×Energy Yield per Liter of O₂\text{Energy Expenditure} = \text{V̇O₂} \times \text{Energy Yield per Liter of O₂}Energy Expenditure=V˙O₂×Energy Yield per Liter of O₂

3️⃣ Respiratory Exchange Ratio (RER) & Fuel Utilization

RER = V̇CO₂ / V̇O₂

Limitations of RER:
❌ Does not account for protein metabolism.
❌ Hyperventilation can cause false readings.
❌ Lactate buildup can cause RER >1.0 due to increased CO₂ exhalation.

4️⃣ Energy Expenditure During Exercise

Metabolic Equivalent (METs)

• 1 MET = 3.5 ml O₂/kg/min (Resting oxygen consumption).

• METs measure exercise intensity by comparing it to resting metabolism.

Energy Cost of Activities

• Walking = 3-4 METs

• Running = 8-12 METs

• Cycling = Varies by resistance & cadence

Cycling Power Output Measurement

• Measured in kg/m/min or Watts

• Higher resistance & speed = greater energy expenditure

5️⃣ Oxygen Consumption (V̇O₂) & Exercise

Oxygen Deficit & EPOC (Excess Post-Exercise Oxygen Consumption)

1️⃣ Oxygen Deficit – Early in exercise, oxygen demand exceeds oxygen supply, leading to anaerobic metabolism.
2️⃣ EPOC (After Exercise) – Oxygen consumption remains elevated to:

• Restore ATP-PCr stores.

• Convert lactate to glycogen.

• Restore hemoglobin & myoglobin O₂ levels.

• Remove accumulated CO₂.

V̇O₂ max (Maximal Oxygen Uptake)

• Best measure of aerobic fitness.

• Influenced by:
  ✅ Heart function (HR, SV, Cardiac Output).
  ✅ Mitochondrial efficiency.
  ✅ Training adaptations (plateaus after 8-12 weeks).

• Higher V̇O₂ max = greater endurance capacity.

6️⃣ Lactate Threshold & Fatigue

Lactate Threshold (LT) = When lactate production exceeds clearance

• Untrained individuals: LT occurs at ~50-60% of V̇O₂ max.

• Trained endurance athletes: LT occurs at ~70-80% of V̇O₂ max.

💡 Higher lactate threshold = better endurance performance!

7️⃣ Fatigue & Its Causes

Types of Fatigue:

1️⃣ Energy Depletion Fatigue:

• ATP-PCr depletion (short-term exercise).

• Glycogen depletion (long-term endurance exercise).

2️⃣ Metabolic Fatigue:

• Lactate accumulation & acidosis → Lowers muscle pH.

• Dehydration & electrolyte loss.

3️⃣ Neuromuscular Fatigue:

• Reduced neurotransmitter release.

• Decreased motor unit recruitment.

💡 Training improves fatigue resistance by increasing mitochondrial function, lactate clearance, and glycogen stores.

8️⃣ Economy of Effort & Training Adaptations

Economy of Movement = Less energy needed for the same output

• More trained athletes require less energy at a given pace.

• Influenced by:
  ✅ Experience/practice.
  ✅ Muscle fiber efficiency.
  ✅ Neuromuscular coordination.

🔹 Elite endurance athletes have:
✔ High V̇O₂ max
✔ High lactate threshold
✔ High economy of movement
✔ More Type I muscle fibers

📌 Study Questions:

1️⃣ What are the three main components of total energy expenditure?
2️⃣ How do we measure energy expenditure? What are the differences between direct and indirect calorimetry?
3️⃣ What does RER tell us about fuel use, and what are its limitations?
4️⃣ What is V̇O₂ max, and why is it important for endurance athletes?
5️⃣ What is oxygen deficit, and how does EPOC aid recovery?
6️⃣ How does lactate accumulation contribute to fatigue?
7️⃣ How do endurance-trained athletes delay fatigue?
8️⃣ Why do trained athletes have a higher lactate threshold?
9️⃣ What factors influence movement economy in endurance sports?

📚 In-Depth Study Guide: Chapter 6 – Fatigue, Muscle Soreness, and Muscle Cramps

(Based on your uploaded PowerPoint and general knowledge from Physiology of Sport and Exercise, 8th Edition)

1️⃣ Introduction to Fatigue

What is Fatigue?

• Fatigue is the inability to maintain required power output to continue muscular work at a given intensity.

• It is multifactorial, meaning it can be caused by various physiological and psychological factors.

Types of Fatigue

✅ Central Fatigue – Fatigue originating from the central nervous system (CNS).
✅ Peripheral Fatigue – Fatigue originating from muscle or neuromuscular junctions.

2️⃣ Causes of Fatigue

1. Inadequate Energy Delivery & Metabolism

• Phosphocreatine (PCr) Depletion

  • PCr is used for short-term, high-intensity efforts.

  • When PCr is depleted, ATP cannot be rapidly replenished, leading to fatigue.

  • Accumulation of inorganic phosphate (Pi) may also contribute to muscle fatigue.

• Glycogen Depletion

  • Glycogen stores deplete more quickly at higher exercise intensities.

  • Once muscle glycogen is gone, liver glycogen must provide glucose.

  • When both are depleted, hypoglycemia (low blood sugar) occurs, leading to fatigue.

2. Accumulation of Metabolic By-Products

• Phosphate (Pi) accumulation – From PCr breakdown, may disrupt contractile function.

• Heat – Increases carbohydrate metabolism but hastens glycogen depletion and impairs muscle function.

• Lactic Acid & H⁺ Ions – H⁺ accumulation lowers pH → Muscle acidosis → Inhibits enzyme activity → Fatigue.

  • pH below 6.9 inhibits glycolysis.

  • pH at 6.4 completely prevents glycogen breakdown.

• Reactive Oxygen Species (ROS) accumulation – Damages mitochondria, slowing ATP production.

3. Failure of Muscle Contractile Mechanism

• Slower rate of force development and slower relaxation.

• Disruption of excitation-contraction coupling:
  ✅ Reduced Ca²⁺ release from the sarcoplasmic reticulum.
  ✅ Magnesium (Mg²⁺) accumulation interferes with calcium release.

4. Altered Neural Control of Muscle Contraction

• Failure at the Neuromuscular Junction:

  • Reduced acetylcholine (ACh) release or synthesis.

  • Increased ACh breakdown in the synapse.

  • Altered muscle resting membrane potential.

• Central Nervous System (CNS) Fatigue:

  • Motor cortex excitability decreases → Fewer muscle fibers are activated.

  • Serotonin buildup in the brain decreases motivation and willpower.

  • Pain tolerance & motivation play a significant role in delaying fatigue.

3️⃣ Psychological Fatigue

✅ Fatigue can be psychological, as seen in ultra-endurance athletes and high-rep weightlifters.
✅ Motivation, self-talk, music, and external factors influence fatigue perception.
✅ Examples of extreme endurance events:

• John L. Sullivan’s 75-round boxing match in 104°F heat.

• Kilian Jornet’s 106-mile ultra-marathon over 32,940 feet elevation.

4️⃣ Heat & Muscle Temperature Effects on Fatigue

🔥 Heat alters metabolic rate → Increases carbohydrate use → Hastens glycogen depletion.
❄ Muscle Pre-Cooling (e.g., ice baths) can prolong exercise and improve endurance.

5️⃣ Critical Power

• The highest exercise intensity that can be sustained for an extended period.

• Correlated with endurance performance.

• Improves with both high-intensity training & endurance training.

6️⃣ Muscle Soreness & Recovery

Types of Muscle Soreness

1️⃣ Acute Muscle Soreness (during or immediately after exercise)

• Caused by metabolic by-product accumulation (H⁺ ions, edema).

• Disappears within minutes to hours.

2️⃣ Delayed-Onset Muscle Soreness (DOMS) (1-2 days after exercise)

• Major cause: Eccentric contractions (e.g., downhill running, heavy squats).

• Structural damage:

  • Z-disc streaming (disruption of sarcomere structure).

  • Myofilament damage (seen after intense eccentric work).

• Inflammation and soreness are connected:

  • White blood cell count increases with soreness.

  • Cytokines initiate inflammation and promote muscle healing.

💡 Should we ice injuries?

• Ice is useful for serious injuries but may slow the natural healing response.

7️⃣ Reducing & Managing DOMS

✅ Minimizing Eccentric Work (progressively increase load).
✅ Gradual training progression.
✅ Recovery methods:

• Stretching

• Massage & Foam Rolling

• Ice Baths / Sauna

• NSAIDs (Non-Steroidal Anti-Inflammatory Drugs)

• RICE Method (Rest, Ice, Compression, Elevation)

8️⃣ Exercise-Induced Muscle Cramps

Types of Muscle Cramps & Their Causes

1️⃣ Exercise-Associated Muscle Cramps (EAMC)

• Occurs in overworked muscles.

• Due to lack of conditioning, dehydration, or poor recovery.

• Treated with stretching and neuromuscular retraining.

2️⃣ Heat Cramps (Electrolyte Depletion Theory)

• Due to large sweat & electrolyte losses (Na⁺, Cl⁻, K⁺, Mg²⁺).

• Treatment: High-sodium drinks, stretching, ice, massage.

9️⃣ Neural Control of Cramps

Neuromuscular Control Theory

• Central origin: Cramps come from hyperexcitable motor neurons.

• Peripheral origin: Cramps caused by spontaneous discharges of motor nerves.

• Risk factors:
  ✅ Lack of fitness
  ✅ Cramping history
  ✅ High-intensity, prolonged exercise

📌 Study Questions:

1️⃣ What are the four major causes of fatigue?
2️⃣ How does PCr depletion contribute to fatigue?
3️⃣ Why does glycogen depletion lead to fatigue?
4️⃣ What metabolic by-products contribute to fatigue?
5️⃣ How does the neuromuscular junction contribute to muscle fatigue?
6️⃣ How does central nervous system fatigue impact performance?
7️⃣ What is the difference between acute soreness and DOMS?
8️⃣ How does inflammation contribute to muscle soreness?
9️⃣ What are the best strategies to reduce DOMS?
🔟 What are the two main types of muscle cramps and how are they treated?