Definition of CO
Volume of blood ejected by heart each minute
CO equation
CO = HR x SV
How does CO change during exercise?
- Increases during exercise
- Due to increase in HR, SV via increased venous return, sympathetic stimulation and Frank-Starling mechanism
How does SV change during exercise?
- Increases during exercise as end-diastolic volume rises and end-systolic volume falls
Minute Ventilation definition
Total volume of air moved into or out of the lungs per minute
Minute Ventilation equation
VE = TV x RR
Tidal volume definition
Volume of air breathed out with each normal breath
Respiratory Rate definition
Breaths per minute
Anaerobic threshold/Ventilatory threshold definition
Exercise intensity at which the body beings to supplement aerobic metabolism with a significant amount go anaerobic energy production, causing lactate and hydrogen ion accumulation in the blood
Ventilatory Efficiency definition
How effectively the respiratory system increases ventilation relative to carbon dioxide production to maintain normal arterial blood gases during exercise; how much O2 is needed to eliminate a given amount of CO2
Why does coronary flow increase during exercise?
To meet increased myocardial consumption; coronary blood flow is the main determinant of myocardial O2 supply
Determinants of myocardial O2
- Heart rate
- Contractility
- Wall tension
Importance of ventilatory efficiency
Gives information on cardiopulmonary health and prognosis in diseases such as HF
When does anaerobic threshold/ventilatory threshold occur?
When VCO2 and VE increases disproportionately to VO2 due to buffering of lactic acid
Autonomic control of exercise response (what is activated/inactivated)
- Exercise triggers increases sympathetic outflow and withdrawal of parasympathetic tone
- Baroreflex and chemoreflex interact during exercise to maintain arterial pressure and gas homeostasis
Types of muscle contractions
- Isotonic = dynamic concentric/eccentric
- Isometric = static
- Isokinetic = constant velocity
Aerobic exercise
Sustained dynamic exercise
Benefits of aerobic exercise
- Increased VO2 max
- Improved mitochondrial density
- Enhanced capillary supply
Resistance exercise
Short bursts of high force
Systemic effects of aerobic exercise
Increases CO, ventilation and peripheral oxygen extraction
Systemic effects of resistance exercise
Causes transient large increases in systolic and diastolic BP
Stimulates muscle hypertrophy and neural adaptations
VO2 and VCO2 changes with exercise
- Increases with workload
- Ventilatory thresholds occur at characteristic points useful for performance and clinical interpretation
Minute ventilation changes with exercise
Increases to meet metabolic CO2 elimination and O2 uptake
SBP changes with exercise
Increases approximately linearly
