Cardiorespiratory Fitness & Exercise Physiology

• Cardiorespiratory fitness (CRF) refers to the circulatory and respiratory systems' ability to supply oxygen to muscles during physical activity.
• VO2max measures CRF.
• VO2 is how well oxygen gets into the lungs (consumption-pulmonary), RBCs move to active skeletal muscle (transport), oxygen extracts from RBC inside muscle, and ATP produces (utilization).
• Having high CRF associates with health benefits and a reduced risk of cardiovascular disease (CVD) due to the systems that transport and utilize oxygen.
• Exercise demonstrates a dose-response relationship with reductions in chronic disease; improving any of the three systems affects VO2.
• The primary role of ACSM-EP is to promote the development and maintenance of CRF.

Anatomy and Physiology Review

• Heart Chambers include:
  • Atria as the upper chambers (left and right)
  • Ventricles as lower chambers (left and right.)
  • The left ventricle drives blood from the heart through the vasculature via stroke volume (SV), i.e., the amount of blood ejected from the left ventricle into the systemic circuit
• Vasculature includes:
  • Veins and venules carry deoxygenated blood.
  • Arteries and arterioles carry oxygenated blood.
  • Capillaries, responsible for gas and nutrient exchange.

Energy Systems

• Creatine phosphate acts as the most immediate source of ATP production.

Cardio Respiratory Response to Exercise: Oxygen Kinetics

• Upon starting exercising, oxygen consumption increases to meet the new energy demands
• Oxygen deficit is related to needed oxygen to perform the activity
• Steady-state oxygen consumption refers to when oxygen demand/consumption plateaus
• Oxygen debt, or EPOC, is correlated with making ATP again once exercise stops.
• Graded exercise can be used to determine baseline fitness and relevant health risks, using increasing intensity levels
• VO2max is determined using the Fick Equation: VO2max = Cardiac Outputmax × (a-vO24 diff max)
  • Cardiac Output is calculated with HR x Stroke Volume
• The a-vO2 difference measures O2 taken by muscles from arterial blood and reflects the difference in O2 content between arterial/venous blood.
• Heart rate increases proportional with workload increase until HRmax is reached, estimated by 220 - age.
• Stroke volume initially increases with workload (up to 40-60% max) w/ little change later in a graded exercise test (GXT).
  • Resting heart rate decreases as stroke volume increases with training.

Pulmonary Ventilation

• Pulmonary Ventilation (VE) linearly increases with workload through moderate intensity (up to ~50-80% max) with more rapid increases near max exertion
• Static diastolic, dynamic diastolic, dynamic systolic, static systolic are all measured during a blood pressure response to exercise
  • As cardiac output increases linearly with workload, so does SBP.
• Pre-exercise should be assessed in the exercise position.
• Assess during exercise at each intensity and post-exercise until stability is achieved.
• One should watch for pre-ex levels
• Rate Pressure Product is an overall assessment of myocardial demand derived from HR and SBP.

Cardiorespiratory Assessment

• Appropriately select CRF assessments in healthy populations.

Primary Considerations when selecting the Appropriate CRF Assessment:

• Intensity, length, and expense
• Type/ amount of personnel
• Needed equipment and facilities
• Physician supervision needs and safety concerns
• Expected results
• Appropriateness of mode
• Willingness of the participant

Metabolic Equivalent of Task (MET)

• MET stands for the metabolic equivalent of task
• MET is the ratio of energy expenditure relative to body weight.
• 1 MET equals 3.5 ml of O2/kg of bw/min.
• This is the amount of energy expended sedentary

FITT-VP

• FITT-VP gives a framework for establishing an exercise prescription program:
  • F = Frequency
  • I = Intensity
  • T = Time (Duration
  • T = Type (Mode)
  • V = Volume (Amount)
  • P = Progression (Advancement)

Aerobic Exercise Recommendations in FITT Variables:

• Frequency must be at least 3 days wk-1. Spreading sessions across 3-5 days wk−1.
• Moderate (40-59% HRR) and/or vigorous (60-89% HRR) intensity recommended for most adults.
• Adults should accumulate 30-60 min d−1 (≥150 min ∙wk-1) of moderate intensity, 20-60 min d−1 (≥75 min wk-1) of vigorous intensity, or a combo.
• Perform aerobic exercise in a continuous or intermittent manner involving major muscle groups is recommended for most adults.
• Volume and intensity are inversely proportional, that creates FITT-VP

Principles of Training:

• Progressive Overload shows a need for exercise exceeding accustomed levels
• Reversibility reverses the overload principle, i.e., "use it or lose it."
  • Cardiorespiratory training decreases/stops; previous improvements will reverse.
• Individual Differences recognize that the same stimulus gives different responses; Genetic factors may play roles.
• Specificity means specific exercise elicits specific adaptations/training effects, also the SAID principle dependent on the mode.

Safe & Effective Exercises to Enhance CRF:

• Walking does not require expensive equipment.
  • Walking has potential safety concerns.
• Jogging/Running is easily accessible.
  • Jogging/Running carries an increased risk of injury.
• Swimming has little impact.
  • Swimming demands skill and may negatively impact respiratory conditions.
• Aerobic machines have multiple options.
  • Aerobic machines are costly and need maintenance, if at home one needs a membership.

Determining Exercise Intensity:

• HRR Method uses heart rate to determine exercise intensity.
• Peak HR Method
• Peak VO2 Method
• Peak MET Method
• VO₂ Reserve Method
• Talk Test Method
• Perceived Exertion Method

Injury with CRF

• Intrinsic Risks include:
  • History of previous injury
  • Inadequate fitness/conditioning
  • Body composition
  • Bony alignment abnormalities
  • Strength or flexibility imbalances
  • Joint/ligamentous laxity.
  • Predisposing musculoskeletal disease.

Extrinsic Risks:

• Excessive load
  • Type/speed/number movement
  • Footwear/surface
  • Training errors/excessive distances/fast progression/high intensity/Poor technique/Fatigue
  • Weather (Adverse environmental conditions, Air quality, Darkness, Heat/cold, High humidity, Altitude, Wind)
  • Worn/faulty equipment.
• The percentage of oxygen (20.93%) in dry air is the same at all elevations.

Abnormal Responses to Exercise:

• Angina
• Drop in BP by 10 mmHg with work rate increase
• Excessive rise in BP: SBP >250 mm Hg and/or DBP >115 mm Hg
• Shortness of breath
• Signs of poor perfusion: light-headedness, confusion, ataxia
• HR failing to increase
• Noticeable change in heart rhythm
• Participant requests to stop
• Severe fatigue
• Testing equipment failure

Assess your knowledge of cardiorespiratory fitness, VO2max, and energy systems during exercise. Questions cover the impact of CRF on health, oxygen extraction efficiency, ATP regeneration, and the Fick equation. Focus on exercise physiology.