Cardiorespiratory Fitness

Define cardiorespiratory fitness (CRF)

CRF is the ability of the circulatory, respiratory, and muscular systems to supply oxygen to working muscles during sustained physical activity and to utilize that oxygen efficiently for energy production.

The physiology of cardiorespiratory system

• Cardiac system pumps oxygenated blood from the heart to the muscles and returns deoxygenated blood to the lungs.

• Respiratory system facilitates gas exchange (O₂ in, CO₂ out) in the alveoli.

• Muscular system uses oxygen in the mitochondria to produce ATP via aerobic metabolism.
  All systems work together to maintain oxygen delivery, energy production, and carbon dioxide removal.

What can we determine by testing for CRF? Why do we measure CRF?

• Determines aerobic capacity, VO₂ max, and exercise tolerance.

• Helps establish training zones, predict performance, and monitor improvement or health status.

• Low CRF is associated with higher risk for cardiovascular disease and mortality.

Health implications and functional implications

Health:

• Higher CRF is linked to reduced risk of heart disease, hypertension, diabetes, obesity, and certain cancers.

• Improves longevity, mental health, and quality of life.

Functional:

• Enhances work capacity, endurance, movement efficiency, and recovery.

• Improves energy utilization and fat metabolism.

• Supports daily activities and athletic performance.

How do each of these systems adapt to cardiorespiratory exercise?

• Muscular system

• Cardiovascular system

• Respiratory system

Muscular:

• Increased mitochondrial density and oxidative enzymes.

• Greater capillary network and myoglobin content.

• Enhanced fat utilization and glycogen storage.

• Delayed onset of fatigue.

Cardiovascular:

• Increased stroke volume and cardiac output.

• Lower resting and submaximal heart rates.

• Improved circulation and capillary density.

• Enhanced oxygen delivery and reduced blood pressure.

Respiratory:

• Increased tidal volume and ventilatory efficiency.

• Improved oxygen diffusion capacity in alveoli.

• Stronger respiratory muscles (diaphragm, intercostals).

• Reduced ventilatory equivalent for oxygen (VE/VO₂) during submaximal exercise.

What is VO2 max and how do we measure it?

Definition:

VO₂ max is the maximum amount of oxygen the body can take in, transport, and utilize during intense exercise — the best measure of aerobic capacity.

How to measure:

• Directly through graded exercise testing (GXT) with gas analysis (measures O₂ intake and CO₂ output).

• Indirectly through submaximal tests (e.g., Rockport Walk, YMCA Cycle, 1.5-mile run).

Increases in cardiorespiratory fitness- explain what happens, changes in VO2 and lactate threshold?

• VO₂ max increases due to improved cardiac output and muscular oxygen extraction.

• Lactate threshold occurs at a higher intensity, allowing sustained effort with less fatigue.

Steady state vs Interval training

• Steady-State: Constant intensity exercise below VT1 (e.g., jogging, cycling).

• Interval Training: Alternating periods of high and low intensity, challenging both aerobic and anaerobic systems.

What are the physiological adaptations to steady-state and interval-based exercise?

Steady-state:

• Improved aerobic metabolism, fat oxidation, and endurance.

• Enhanced stroke volume and oxygen utilization efficiency.

Interval-based:

• Increased VO₂ max, lactate clearance, and anaerobic capacity.

• Improved speed, power, and metabolic flexibility.

Ventilatory Response to Increasing Exercise Intensity

As intensity rises, ventilation (VE) increases linearly until VT1, then nonlinearly after VT2 due to increased CO₂ production and lactic acid buffering.

Ventilatory Effects During Aerobic Exercise

• Tidal volume and respiratory rate increase.

• Gas exchange efficiency improves.

• Enhanced oxygen uptake supports prolonged activity.

Components of a workout session. Describe the purpose of the warm- up, conditioning phase, and cool- down. What should each phase look like

• Warm-Up: Gradually increases HR, blood flow, and temperature; prepares muscles and reduces injury risk (5–10 min, low-moderate intensity).

• Conditioning Phase: Main workout targeting specific goals (20–60 min, moderate to vigorous intensity).

• Cool-Down: Gradual recovery; aids venous return, prevents blood pooling, promotes flexibility (5–10 min of light activity).

Environmental Considerations When Exercising

• Heat: Increases HR and sweat rate; risk of dehydration and heat illness.

• Cold: Causes vasoconstriction, shivering, and risk of hypothermia; wear layers and protect extremities.

• Altitude: Lower O₂ availability; reduced endurance until acclimatization (~7–10 days).

• Air Pollution: Decreases performance and may irritate respiratory tract; exercise indoors if poor air quality.

ACE Integrated Fitness Training Model- cardiorespiratory Training, know the 3 phases, what is the focus and emphasis of each stage, and how do we train clients in each stage

1. Base Training: Develop consistent activity and aerobic base below VT1; focus on frequency and duration.

2. Fitness Training: Increase aerobic efficiency and performance; introduce intervals up to VT2.

3. Performance Training: Enhance anaerobic capacity and endurance; train near or above VT2.

Know the three zones of the training model and how they relate to the 3 phases.

• Zone 1 (Below VT1): Base Training – light/moderate intensity, building endurance.

• Zone 2 (Between VT1–VT2): Fitness Training – aerobic efficiency and threshold development.

• Zone 3 (Above VT2): Performance Training – high-intensity, anaerobic power and tolerance.

What is lactate threshold? Effect of training on lactate threshold

The point during exercise when lactate production exceeds clearance, leading to faster fatigue. Training raises the threshold, allowing higher intensities for longer durations.

What is VT1? What are some contraindications to performing this test?

VT1:

• The intensity where breathing becomes noticeably heavier but conversation is still possible.

• Represents the shift from primarily aerobic metabolism to partial anaerobic contribution.

Contraindications:

• Cardiovascular or pulmonary disease, uncontrolled hypertension, recent illness or injury, or lack of medical clearance for submaximal exertion.

What is VT2? What does it correspond with? (Onset of Blood Lactate Accumulation (OBLA and what is OBLA?)

• The point where talking becomes difficult; heavy breathing due to high CO₂ accumulation.

• Corresponds with OBLA (Onset of Blood Lactate Accumulation)—around 4 mmol/L of lactate.

OBLA definition:
The point where lactate rapidly accumulates in the blood, signaling transition to primarily anaerobic metabolism.

General Guidelines for Cardiorespiratory Exercise for Health and Fitness

• Frequency: ≥5 days/week (moderate) or ≥3 days/week (vigorous).

• Intensity: 64–95% HRmax (based on fitness).

• Time: 20–60 minutes per session.

• Type: Large muscle group, rhythmic activities (e.g., walking, cycling, swimming).

• Volume: ≥500–1000 MET-min/week.

• Progression: Gradual increases in duration, frequency, or intensity.

What does FITT-VP stand for? Know how to explain each component.

• F – Frequency

• I – Intensity

• T – Time

• T – Type

• V – Volume

• P – Progression
  Each component helps structure safe, effective exercise programming.

Karvonen Method to estimate exercise intensity for

Example: HRmax = 200, HRrest = 60, intensity = 70% → (200-60)×0.7 + 60 = 158 bpm target HR.

Reducing Sedentary Timehow do we apply the FITTformula to a sedentary client?

• Frequency: Begin with short bouts (2–3 times/day).

• Intensity: Light to moderate (RPE 2–3).

• Time: Start with 10–15 min, gradually increase.

• Type: Low-impact, enjoyable activities (walking, stationary cycling).
  Focus on consistency over intensity.

Know the difference between maximal, submaximal assessments and field assessments

• Maximal: Measures true VO₂ max via graded exercise test with gas analysis; lab-based.

• Submaximal: Estimates VO₂ max using HR response (e.g., YMCA Cycle, Rockport Walk).

• Field Assessments: Simple, practical tests (e.g., 1.5-mile run, step test) for large groups or limited resources.