1. Introduction
- During
exercise, muscle activity increases, which raises the demand for
oxygen and nutrients.
- The cardiovascular
system (CVS) responds by adjusting heart rate, cardiac output, and
blood flow to match the metabolic needs of the body.
2. Types of Exercise
- Dynamic
(Isotonic): Running, swimming, cycling
- Static
(Isometric): Weightlifting, plank
Each affects CVS differently.
3. Cardiovascular
Changes During Exercise
A. Heart Rate (HR)
- Increases
due to sympathetic stimulation
- Proportional
to intensity of exercise
B. Stroke Volume (SV)
- Increases
due to:
- ↑ Venous
return
- ↑
Myocardial contractility
C. Cardiac Output (CO)
- CO = HR ×
SV
- Increases
4–6 times in intense exercise
D. Blood Pressure (BP)
- Systolic
BP increases
- Diastolic
BP:
- May
remain normal or slightly ↓ in dynamic exercise
- ↑ in
isometric/static exercise
E. Peripheral Resistance
- Decreases
in active muscles due to vasodilation
- Increases
in non-essential areas (like GIT)
F. Blood Flow Redistribution
|
Organ/Tissue |
Change in Blood Flow |
|
Skeletal muscles |
↑↑↑ (active muscles) |
|
Skin (later phase) |
↑ (for cooling) |
|
GIT & kidneys |
↓ |
|
Heart & brain |
Maintained or slightly ↑ |
4. Mechanisms of CVS
Regulation in Exercise
A. Neural Mechanisms
- Central
command from brain activates sympathetic system
- Baroreceptor
resetting maintains BP despite high CO
B. Local Mechanisms
- Metabolic
vasodilation in muscles:
- ↑ CO₂, ↑
H⁺, ↑ temperature, ↓ O₂ → vasodilation
C. Hormonal Factors
- Adrenaline
and noradrenaline → ↑ HR & contractility
5. Benefits of Regular
Exercise on CVS
- Improves cardiac
efficiency
- Lowers resting
heart rate
- Improves circulation
- Reduces risk
of cardiovascular diseases
- Enhances oxygen
delivery to tissues
6. Clinical Importance
|
Condition |
Exercise Response |
|
Hypertension |
Monitor BP; avoid isometric |
|
Ischemic heart disease |
Graded exercise, avoid overexertion |
|
Heart failure |
Low-intensity supervised exercise helps |
Mnemonic for CVS
Changes During Exercise – "H-CO-BP-VD"
- H – ↑ Heart
Rate
- CO – ↑
Cardiac Output
- BP – ↑
Systolic BP
- VD –
Vasodilation in active muscles
