Biomechanics: Muscle contractions
Notes
Introduction to OMM
Biomechanics: Muscle contractions
A contraction is defined simply as the generation of tension within a muscle fiber. Muscle fibers generate tension through actin and myosin cross-bridge cycling. Under tension, a muscle belly can either lengthen, shorten, or remain the same length. The names of contractions are based upon how the muscle belly length changes during this tension.
Isokinetic contractions are those in which there is a consistent rate of speed.
Isotonic contractions are those in which there is consistent tension as the muscle length changes. These can be either concentric (muscle shortening) or eccentric (muscle elongation).
Isometric contractions are those in which the length of the muscle does not change.
Isokinetic contractions are those in which there is a consistent rate of speed.
Isotonic contractions are those in which there is consistent tension as the muscle length changes. These can be either concentric (muscle shortening) or eccentric (muscle elongation).
Isometric contractions are those in which the length of the muscle does not change.
TYPES OF MUSCLE CONTRACTIONS | ||
| TYPE OF CONTRACTION | DEFINITION / CHARACTERISTICS | EXAMPLE |
| Isokinetic | When the velocity of the muscle contraction remains constant while muscle length changes | Riding a stationary bike |
| Concentric (isotonic) | When a muscle is activated and required to lift a load which is less than the maximum tension it can generate, resulting in muscle shortening | Raising a dumbbell with a bicep curl |
| Eccentric (isotonic) | When the external force on a muscle is greater than the maximal force it can generate, resulting in muscle lengthening | Walking down stairs |
| Isometric | When a muscle is activated at a constant length | Holding a shopping bag |
Figure 1. Riding a stationary bike, raising a dumbbell with a bicep curl, and holding a weight at a constant height are examples of isokinetic, isotonic, and isometric contractions, respectively.