Mastering the Science of Blood Flow

Ejection Fraction and Stroke Volume

• Ejection fraction (EF) can be calculated using the equation: EF = (stroke volume / end-diastolic volume) x 100%.
• Average ejection fraction value is typically around 55% to 70%.
• Factors affecting stroke volume (SV) include preload, afterload, and contractility.
• Average stroke volume per beat ranges from 60 to 100 mL.

Cardiac Output and Mean Arterial Pressure

• Cardiac output (Q) is calculated using the equation: Q = heart rate (HR) x stroke volume (SV).
• Mean arterial pressure (MAP) can be calculated with the formula: MAP = (cardiac output x total peripheral resistance) or MAP = DBP + 1/3(SBP - DBP).
• Pulse pressure (PP) is calculated as: PP = systolic blood pressure (SBP) - diastolic blood pressure (DBP).

Heart Contractions and Hemodynamics

• The phase before heart contractions is known as diastole.
• The pressure the heart pumps against to eject blood is referred to as afterload.

Body Composition and Training

• Body composition, size, and training status influence various cardiovascular parameters.
• Increased muscle mass positively correlates with increased stroke volume.

Maximum Heart Rate

• Maximum heart rate (HR) is estimated with the formula: 220 - age, with slight differences noted between males and females.

Exercise, Blood Clotting, and ATP Production

• Exercising generally reduces the risk of thrombosis (blood clot formation).
• Glycolysis yields a net production of 2 ATP molecules per glucose molecule.
• The Krebs cycle generates 2 ATP molecules from the breakdown of one glucose molecule.
• The electron transport chain produces an additional 28-34 ATP molecules from one glucose.

Training and Detraining

• Detraining leads to physiological declines in strength and endurance.
• Longer training duration is directly associated with greater improvements in fitness levels.
• Cardiac hypertrophy increases muscle mass and efficiency of the heart.

Baroreceptors and Blood Flow

• Baroreceptors function to monitor blood pressure and help regulate heart rate.
• Capillarization enhances oxygen and nutrient delivery to tissues.
• According to Poiseuille's Law, vessel diameter significantly impacts blood flow rate.
• Vasodilation results in widening of blood vessels, reducing resistance and increasing blood flow.

Reynold's Number and Blood Flow Distribution

• Reynold's number predicts flow patterns in different fluid conditions, with low values indicating laminar flow.
• Blood flow distribution is influenced by metabolic needs and exercise intensity.
• During static exercise, blood flow may be reduced to non-active muscle groups in favor of those participating in the activity.