Cardiorespiratory Fitness (CRF)

• Cardiorespiratory fitness (CRF) assessments and exercise programs are designed for apparently healthy participants.

What is CRF?

• CRF is the ability of the circulatory and respiratory systems to supply oxygen to muscles during physical activity.
• VO2max is an indicator of CRF.
• VO2 depends on effectiveness of oxygen intake into the lungs, transport of RBCs to muscles, and oxygen extraction from RBCs for ATP production.
• High CRF is associated with health benefits and a reduced risk of cardiovascular disease.
• Improvement in any of the three systems—consumption, transport, or utilization—will be reflected in VO2.
• ACSM-EP's role is to develop and maintain CRF.

Anatomy and Physiology Review

• Heart Chambers consist of the atria and ventricles.
• The right and left Atria are the upper chambers.
• The Right and left Ventricles are the lower chambers.
• The left ventricle drives blood from the heart through the vasculature, known as stroke volume (SV)
• Vasculature consists of veins, venules, arteries, arterioles, and capillaries.
• Veins and venules transport deoxygenated blood.
• Arteries and arterioles transport oxygenated blood.
• Capillaries facilitate gas and nutrient exchange.

Cardio Respiratory Response to Exercise: Oxygen Kinetics

• During exercise, oxygen consumption increases to meet the demands of the activity.
• Oxygen deficit occurs at the start of exercise when oxygen supply is not yet adequate and steady-state oxygen consumption reflects a balance between supply and demand.
• After exercise, excess post-exercise oxygen consumption (EPOC) or oxygen debt, occurs as the body recovers to its resting state.

VO2max and the Fick Equation

• The Fick Equation determines VO2max.
• VO2max = Cardiac Outputmax × (a-vO2△ diff max)
• Cardiac Output = Heart Rate (HR) x Stroke Volume

Cardiovascular responses to GXT (Graded Exercise Test)

• a-vO2 Difference: difference in oxygen content between arterial and venous blood.
• At rest, the a-vO2 difference is low.
• The Heart Rate increases with workload untill maximum HR is reached.
• Maximum Heart Rate is calculated with 220-age.
• Stroke Volume increases with workload initially up to 40-60% max.
• Stroke Volume increases with training, and resting heart rate decreases.
• Pulmonary Ventilation (VE) linearly increases with workload through moderate intensity (50-80% max).

Blood Pressure Responses

• During exercise, dynamic systolic blood pressure increases.
• Dynamic diastolic blood pressure changes slightly.

Assessments During Exercise

• Pre-Exercise: assess in the set exercise position
• During Exercise: assess at each exercise intensity
• Post-Exercise: assess until reaching stability
• Rate Pressure Product measures the heart's myocardial demand by muliplying heart rate by systolic blood pressure.

Selecting CRF Assessments

• CRF assessments are performed in both healthy and clinical populations. Primary considerations include:
• Intensity, length, and expense of the test.
• Type and number of personnel.
• The needs for Equipment and facilities.
• Concerns Physican supervision and safety.
• Required accuracy of results.
• Appropriateness of mode of exercise.
• Willingness of the participant to perform the test.
• A "one-size-fits-all" approach should be avoided

Common CRF assessment techniques

• Maximal oxygen uptake (VO2max) tests the intensity at maximum and requires treadmill, cycle ergometer, or arm ergometer for equipment.
• Submaximal oxygen uptake tests the intensity at submaximal and requires cycle ergometer for equpment.
• Step tests tests at maximal or submaximal and requires aerobic step or specific height bench as well as a metronome for equipment.
• Field tests tests at maximal or submaximal and requires a level walking/running surface.

Metabolic Calculations and METs

• 1 MET (metabolic equivalent of task) equals 3.5 ml of O2/kg of body weight/minute,
• MET provides a way to express the energy cost of activities as a multiple of the resting metabolic rate.
• MET is the energy you expend when sitting.

FITT-VP

• FITT-VP is a framework for creating an exercise prescription program including Frequency, Intensity, Time, Type, Volume, and Progression.
• Aerobic exercise should be performed at least 3 days per week.
• Spreading exercise across 3–5 days per week is recommended.
• Most adults should participate at moderate, or vigorous intensity.
• 30-60 minutes per day of moderate-intensity exercise(150 minutes per week).
• Perform aerobic exercise performed continuously or intermittently.

4 Principles of Training

• Progressive Overload: Exercise needs to be greater than accustomed to induce adaptation.
• Reversibility: 'Use it or lose it' or the oppostive of the overload principle.
• Individual Differences: The same stimulus can produce varying responses within individuals impacted by genetic factors.
• Specificity: States that specific adaptations from specific training effects will occur from exercising (ex. if you want to get good at sprinting, you sprint).

Safe & Effective Exercises

• Walking is effective because it can be done indoors or outdoors, and does not require expensive equipment or skill.
• Downside of walking is potential safety concerns.
• Jogging/Running is a good option that is easily accessible and promotes bone health.
• Can provide a high risk of injury.
• Bicycling can reduce impact to joints and bones.
• Weather and safely are needed.
• Swimming doesn't impact the joints and is known to aliviate asthma.
• It requires skill and the pool may aggravate respiratory conditions.
• Aerobic machines have multiple options allowing exercise, regardless of weather conditions.
• Can lead to expenses.

Determining Exercise Intensity

• Measuring using direct or subjective approaches
• Heart Rate Reserve (HRR) Method
• Peak Heart Rate Method
• Peak VO2 Method
• Peak MET Method
• VO₂ Reserve Method
• Talk Test Method
• Perceived Exertion Method

Abnormal Responses to Exercise

• Angina or angina-like symptoms
• Significant drop in SBP with increased work rate
• Excessive rise in blood pressure
• Shortness of breath
• Signs of bad profusion
• Heart rate's failure to increase with exercise
• Participant requests to stop
• Bad fatigue
• Equipment failure

Injury Risks During Exercise

• Intrinsic risk factors are history of injury, bad fitness, body composition, strength imbalances, and predisposing diseases.
• Extrinsic factors are the load of the body, type, speed and number of repetitions of the movement, footwear, training errors, or poor technique.
• Additional factors are distance, progression, intensity, running on hills, fatigue, environmental conditions, darkness, altitude, wind, and equipment issues.

Cardiorespiratory fitness (CRF) is the circulatory and respiratory systems' ability to supply oxygen to muscles during activity. VO2max indicates CRF and depends on oxygen intake, RBC transport, and oxygen extraction for ATP production. High CRF is associated with health benefits and reduced cardiovascular disease risk.