Physiology · Cardiovascular System

Exercise physiology and cardiovascular responses

5 min read

Definition

Isotonic (dynamic) exercise: isotonic muscle contraction, muscle length changes, external work is done, e.g. walking, jogging.
Isometric (static) exercise: isometric muscle contraction, muscle length unchanged, no external work is done, e.g. pushing against a wall.

Degrees of Exercise

Degrees of exercise by heart rate rise

Degree	HR rise	O2 consumption	Work done
Mild	~25% (80 to 100/min)	0.5 to 1 L/min	150 to 350 watts
Moderate	~50% (80 to 120/min)	1 to 2 L/min	350 to 550 watts
Severe	~80% (80 to 144/min)	1.8 to 2.5 L/min	550 to 700 watts
Very severe	~100% (80 to 160/min)	>2.5 L/min	>700 watts

Degree

Mild

HR rise: ~25% (80 to 100/min)
O2 consumption: 0.5 to 1 L/min
Work done: 150 to 350 watts

Moderate

HR rise: ~50% (80 to 120/min)
O2 consumption: 1 to 2 L/min
Work done: 350 to 550 watts

Severe

HR rise: ~80% (80 to 144/min)
O2 consumption: 1.8 to 2.5 L/min
Work done: 550 to 700 watts

Very severe

HR rise: ~100% (80 to 160/min)
O2 consumption: >2.5 L/min
Work done: >700 watts

Isotonic contraction is concentric (muscle shortens against a force, e.g. climbing stairs) or eccentric (muscle lengthens resisting a load, e.g. walking down stairs).