ch 6,10,12,16 Sophia's flahscrads for the physiology of Exercise exam 4/7

What is VO2 max

the maximum amount of oxygen your body can use during intense exercise.

• Point at which O2 consumption does not increase with further increase in intensity

• Best single measurement of aerobic fitness

what is lactate threshold

the exercise intensity at which your body starts producing lactate faster than it can clear it, causing it to build up in your blood.

what does lactate threshold determie

• It determines how fast and long you can sustain effort

• A higher lactate threshold means you can:

  • Run/cycle faster without fatiguing

  • Maintain hard effort longer

VO2 max is not best predictor of…

endurance performance

VO2 max plateaus after…

8 to 12 weeks of training but can still increase

what is economy of effort

How much energy (or oxygen) you use to do the same amount of work

what is O2 deficit

O2 required − O2 consumed

• Occurs when anaerobic pathways are used for ATP

production (from rest to exercise)

why does oxygen deficit happen

O2 required (demand) > O2 consumed in early exercise

At the start of intense exercise, your body can’t deliver oxygen to the muscles fast enough, so it relies on anaerobic energy systems (like glycolysis and ATP-PC).

this is why you produce lactate early in exercise—it’s anaerobic energy filling the gap.

What is EPOC

O2 consumed > O2 required (demand) in early recovery

After exercise, your breathing stays elevated to “repay” the oxygen deficit and restore your body to pre-exercise state.

What physiologically happens during EPOC

ATP/PCr stores replenished, lactate to

glycogen, hemo/myoglobin replenished, excess CO2

cleared

Lactate threshold for trained vs untrained

Untrained: L threshold occurs at approx. 50-60% of

VO2max

Trained: L threshold occurs at approx. 70-80% of

VO2max

Higher lactate threshold =

higher sustained

exercise intensity = better endurance

performance

what improves economy of effort

PRACTICE

Fatigue in short, high-intensity exercise

seconds to few mins, Accumulation of inorganic phosphate (Pi) and other metabolites in the muscle

1. ATP breakdown releases Pi → binds with calcium → reduces muscle contraction efficiency

2. Hydrogen ions (from anaerobic glycolysis) can also contribute to acidosis, affecting enzyme function

• Result: Muscle can no longer contract maximally → fatigue occurs quickly

Fatigue in long-duration exercise

more than 90 mins, (endurance sports) Glycogen depletion

1. Muscle and liver glycogen stores decrease → less glucose available for ATP production

2. Body relies more on fat oxidation, which is slower → energy supply can’t meet demand

• Result: Reduced force output and slower contraction → “hitting the wall” or bonking in endurance events

PCr used for

short-term, high-intensity effort

• PCr depletes more quickly than total ATP

• Pi accumulation may be potential cause

Glycogen Depletes more quickly during…

first few minutes of

exercise versus later stages

Muscle glycogen depletion (hypoglycemia) =

fatigue via interference of Ca2+ release from SR

Certain rate of muscle glycogenolysis required to

maintain ….function

oxidative system

Products of fatigue

Inorganic Phosphate (Pi)

• Source: Rapid breakdown of phosphocreatine (PCr) and ATP during high-intensity exercise.

• Effect:

  • Inhibits the sarcoplasmic reticulum (SR) release of Ca²⁺, reducing the ability of muscles to contract efficiently.

Lactic Acid / Lactate + H⁺

• Source: Anaerobic glycolysis produces lactic acid, which dissociates into lactate and hydrogen ions (H⁺).

• Effect:

  • ↑ H⁺ concentration → reduces pH (acidosis)

Heat

• Source: Metabolic reactions generate heat; exercise increases core temperature.

• Effect:

  • High temperature → increased blood flow to skin for cooling → reduced blood supply to muscles

What is Hyperthermia

• Higher temperature causes a greater rate of carbohydrate utilization, which:

  • Hastens glycogen depletion

  • Leads to earlier onset of fatigue during prolonged exercise

High muscle temperature may impair muscle contraction

Cooling muscles before exercise can:

• Lower initial core and muscle temperature

• Delay glycogen depletion and metabolic strain

• Prolong exercise duration

is lacate present in lactic acid

no

lactate is

a valuable energy source within the

working muscle, non-working muscle, and heart, 2)

quantitatively the most important contributor to the

making of glucose in the liver, and 3) subject to training-

induced improvements in its use as a fuel

What do buffers do?

delay fatigue by maintaining pH.

Buffers minimize drop in pH (7.1 to 6.5)

• Cells survive but don’t function well

If muscle ph is less than 6.9, or is 6.4 then

pH <6.9 inhibits glycolytic enzymes, ATP

synthesis

• pH = 6.4 prevents further glycogen

breakdown

What causes fatigue??

NOT LACTATE

H⁺ ions (from glycolysis) contribute to fatigue by lowering pH, inhibiting enzymes, and reducing force production.

How is lactate useful

Fuel source via oxidation in type 1 fibers or gluconeogenesis (cori cycle)

What neural factors contribute to fatigue?

Neuromuscular junction failure: ↓ ACh synthesis/release, altered breakdown, increased fiber stimulus threshold, altered resting membrane potential → reduced muscle activation.

How does the central nervous system (CNS) contribute to fatigue?

CNS limits voluntary muscle activation, influences perception of effort (RPE), and acts as a protective warning; elite athletes can train to tolerate fatigue and pace better.

1 repetition maximum (1RM

maximal weight that can

be lifted with a single effort

Muscular power

rate of performing work

Power = force x (distance/time)

Endurance

capacity to perform repeated muscle contractions (or sustain a single

contraction over time)

Hypertrophy vs hyperplasia

Hypertrophy: muscle fiber bigger, hyperplasia: more muscle fibers

Aerobic power

rate of energy release by oxygen- dependent metabolic processes

Anaerobic power:

rate of energy release by oxygen-independent metabolic processes

What is the Principle of Individuality?

Performance and training adaptations vary between individuals due to genetics, differences in cell growth rates, metabolism, cardiorespiratory, and neuroendocrine regulation. Some are high responders, some low responders.

Why is the Principle of Individuality important in training?

Training programs must be personalized because not everyone responds the same way to the same program.

What is the Principle of Specificity?

Training adaptations are specific to the type, mode, and intensity of exercise performed. Programs must stress the most relevant physiological systems for the athlete’s sport.

How does the Principle of Specificity affect training program design?

Adaptations are highly specific to activity type, volume, and intensity, so exercises must mimic the demands of the sport.

What is the Principle of Reversibility?

“Use it or lose it.” Gains in strength and endurance from training are reversed if training stops (detraining).

How does detraining affect performance?

Stopping training leads to loss of strength, endurance, and physiological adaptations gained during training.

What is the Principle of Progressive Overload?

To improve, the body must be challenged beyond its normal load. Over time, resistance, repetitions, or intensity must increase to continue improving strength or endurance.

How do you apply progressive overload in strength training?

As strength increases, increase resistance or repetitions to keep challenging muscles and stimulate further gains.

What is the Principle of Variation?

Also called periodization; systematically changes training variables (volume, intensity, mode) to keep training challenging and avoid plateaus.

Why is variation/periodization important?

Prevents overtraining, promotes continuous adaptation, and allows recovery while targeting specific performance goals.

How can training variables be manipulated under this principle?

• increase volume / decrease intensity → builds endurance or base fitness

• Decrease volume / increase intensity → builds strength, power, or peak performance

• Can also change mode of training for variety and specificity

What is a microcycle?

the shortest training cycle, usually week-to-week, focusing on specific workouts and recovery periods.

What is a mesocycle?

A medium-length cycle, usually several weeks to a month, designed to achieve specific adaptations (e.g., hypertrophy, strength, endurance).

What is a macrocycle?

The longest cycle, often spanning an entire training year or season, incorporating multiple mesocycles for overall performance development and peaking.

How do microcycle, mesocycle, and macrocycle relate?

• Microcycle: weekly plan

• Mesocycle: 4–6 weeks or a month, made up of multiple microcycles

• Macrocycle: entire program/season, made up of multiple mesocycles

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What is concentric training (CON)?

Training that focuses on muscle shortening under load.

• Example: lifting phase of a bicep curl.

What is eccentric training (ECC)?

Training that focuses on muscle lengthening under load.

• Example: slowly lowering a squat or bench press.

In this phase, muscle’s ability to resist force greater than

with CON training

Theoretically produces  strength gains versus CON

What is isometric training?

Training where the muscle produces force without changing length.

• Example: holding a plank, wall sit, or static squat.

What is the exercise order (priority system) for training?

• Large muscle groups before small

• Multi-joint exercises before single-joint

• High-intensity exercises before low-intensity

How should rest periods be structured based on experience?

• Novice/intermediate lifters: 2–3 minutes between sets

• Advanced lifters: 1–2 minutes between sets

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What is isokinetic training?

Training in which movement occurs at a constant (fixed) speed, regardless of the force applied.

What are plyometrics?

Also called stretch-shortening cycle exercises; training that uses the stretch reflex to generate powerful movements.

purpose: bridge the gap between speed and strength training, improving explosive power.

How do plyometrics work?

Jump squats, Box jumps

• Eccentric (ECC) phase: muscle stretches and stores elastic energy

• Concentric (CON) phase: stored energy is released for powerful movement

• Minimal amortization phase: short transition between ECC and CON to maximize force

What are muscle spindles?

Sensory receptors in muscles that detect stretch and changes in muscle length, informing the brain about joint angles.

• Provide feedback on joint angles and muscle length

• Trigger the stretch reflex, which can cause a muscle contraction to resist overstretching

• Example: Brain knows when your arm is at 90° flexion or shoulder at 90° abduction

What are Golgi tendon organs (GTOs)?

Sensory receptors in tendons that detect excessive force or tension on a muscle-tendon unit.

• Inhibit maximal contraction to prevent injury when force is too high

• Acts as a protective mechanism against tendon or muscle damage

What is stroke volume (SV)?

The amount of blood ejected by the left ventricle of the heart per heartbeat.

•  (EDV)−(ESV)

What is cardiac output (CO)?

The total volume of blood pumped by the heart per minute.

CO=Stroke Volume (SV)×Heart Rate (HR)

Overall benefits of aerobic training adaptations

• Stronger, more efficient heart (↑ SV, LVH)

• Better oxygen delivery (↑ capillaries, blood volume)

• Improved energy production (↑ mitochondria)

• Enhanced endurance performance

What is left ventricular hypertrophy (LVH)?

Enlargement and thickening of the left ventricle from aerobic training.

• Purpose: Pumps more blood per beat → higher stroke volume

• Result: More efficient heart and improved endurance performance

How does capillarization adapt with aerobic training?

Increased number of capillaries around muscle fibers.

• Purpose: Delivers oxygen and nutrients more efficiently to active muscles

• Benefit: Enhances oxygen extraction and waste removal

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How do mitochondria adapt to aerobic training?

Increase in size and number of mitochondria in muscle fibers.

• Purpose: More ATP production via oxidative phosphorylation

• Benefit: Delays fatigue, supports sustained aerobic activity

How does blood volume change with aerobic training?

Plasma volume increases, improving:

• Stroke volume

• Cardiac output

• Thermoregulation

• Oxygen delivery to working muscles

does aerobic training affect resting heart rate (RHR)?

Yes, it decreases.

• Heart becomes more efficient due to increased stroke volume and cardiac output

• Typical reduction: 5–15 bpm

• Example: A trained athlete may have a resting HR of 50 bpm compared to 70–80 bpm untrained

does aerobic training affect submaximal heart rate?

Yes, it decreases.

• At a given submaximal workload, the heart doesn’t have to beat as fast

• Reason: higher stroke volume delivers the same cardiac output with fewer beats

• Benefit: less cardiovascular strain during moderate exercise

does aerobic training affect maximal heart rate (HRmax)?

No, HRmax does not change.

• HRmax is determined primarily by age:

HRmax=220−age

In aerobic training resting and submaximal BP…also blood volume

decreases, increases: rise in RBC, plasma volime, water and Na+ retention

in aerobic training maximal bp…

may increase or stay the same

How does resting , submax, and maxVO₂ change with aerobic training?and When is the highest VO₂max typically achieved?

resting: unchanged

submax: unchanged

max: substatially increases (15-20%)

After 12–18 months of consistent training.

How does training affect the ATP-PCr system?

• Little enzymatic change with general training

• System-specific training (sprints, explosive lifts) increases strength and power

How does training affect the glycolytic system?

Increase in key glycolytic enzymes: phosphorylase, PFK, LDH, hexokinase

• Performance gains mainly from increased strength and power, not just enzyme activity

How does aerobic training affect lactate accumulation vs clearance?

• Trained muscles produce less lactate at given workload

• Lactate is cleared faster via oxidation in type I fibers or gluconeogenesis in the liver

• Result: sustained high-intensity exercise is possible

What happens during glycolysis in short-duration high-intensity exercise (15 sec – 2 min)?

• Anaerobic glycolysis dominates

• ATP-PCr system contributes early (first 10–15 sec)

• Glycolytic enzyme activity can increase with training

• Training enhances lactate clearance, delaying fatigue

What is acute overload in training?

A short-term increase in training stress above the body’s normal workload to stimulate adaptation.

• Examples: lifting heavier weight than usual, running faster or longer for one session

What is detraining?

The loss of training-induced adaptations due to reduced training or complete cessation.

what is excessive training

Training where volume and/or intensity are taken to an extreme, beyond what the body can recover from.

• Can decrease performance in strength, speed, or endurance

Immune function

factor compromised in onset of overtraining syndrome (also seen in overreaching)

What is overreaching in training?

A short-term increase in training stress that temporarily reduces performance, but is planned and recoverable.

What is overtraining?

Unexplained decrease in performance, function for weeks, months, or years

Overtraining is a condition where exercise exceeds the body’s ability to recover, leading to decreased performance and fatigue.

What is Overtraining Syndrome (OTS) and how to treat?

A chronic condition caused by excessive training stress that leads to long-term performance decline and multiple physical/psychological symptoms.

• Causes: Not fully understood

• prevention: periodization training, adequate caloric intake

• Treatment:

  • Reduce training intensity or take weeks to months of rest

  • Counseling to manage stress

  • Address sleep disorders

  • Correct nutritional imbalances

What is periodization?

The systematic planning of training in cycles to maximize performance and recovery.

• Varies intensity, volume, and type of training over time

• Helps prevent overtraining and promotes progressive overload

• Includes cycles such as:

  • Microcycle: week-to-week

  • Mesocycle: month-long phases

  • Macrocycle: full training season or year

what is tapering

A planned reduction in training volume and/or intensity before a major competition to allow recovery and healing.

• Duration: 4–28 days or longer

• Increased muscular strength and power

• Muscle repair and replenished glycogen reserves

• May improve contractile mechanisms

How does tapering affect VO₂max and performance?

• Can reduce training by 60% while maintaining VO₂max

• Leads to improved performance:

  • ~3% better race times

  • 18–25% improved arm strength/power

What is undertraining?

A training situation where volume and/or intensity are too low to cause significant physiological adaptations.

What happens to resting testosterone and cortisol with excessive training?

• Testosterone decreases (anabolic hormone)

• Cortisol increases (catabolic hormone)

How is the T:C ratio related to overtraining syndrome (OTS)?

• A reduced ratio can be a marker of overtraining

• Suggests the body is under excessive training stress and not recovering properly

• Often seen in volume-related overtraining

What is the neural transmission theory?

• Fatigue occurs at the neuromuscular junction, preventing proper muscle activation

• Possible causes:

  • Decreased acetylcholine (ACh) synthesis/release

  • Altered ACh breakdown in synapse

  • Increased muscle fiber stimulus threshold

  • Changes in muscle resting membrane potential

What is the central nervous system (CNS) theory?

• Fatigue is partly regulated by the brain and spinal cord

• Factors:

  • Conscious fiber recruitment

  • Perception of pain (RPE)

  • Elite athletes can train the brain to tolerate fatigue and pace properly

Sympathetic Nervous System Responses to overtraining

Increased BP

Loss of appetite

Weight loss

Sleep and emotional disturbances

Increased basal metabolic rate

Overtraining Syndrome: Parasympathetic Responses

More common with endurance athletes

Early fatigue

Decreased resting HR

Decreased resting BP

Rapid heart rate recovery

What is transient hypertrophy?

Temporary increase in muscle size immediately after training due to fluid (edema) accumulation; disappears within hours

What is chronic hypertrophy?

Long-term structural increase in muscle fiber size from consistent resistance training (more myofibrils, sarcoplasm, connective tissue)

What are the key training variables to manipulate?

Volume (sets × reps × load), intensity (%1RM or effort), load (weight), frequency (days per week), and mode (exercise type)