Each muscle in our body contains a mixture of different types of muscle fibers. This diversity in muscle fibers provides different functions.
There are three types of muscle fibers. These are slow oxidative, fast oxidative, and fast glycolytic. Most of the muscles in our body contain these three fibers. These fibers are able to adapt to physical demands and change size and fiber size.
There are three types of muscle contractions used to gain strength. Those contractions are classified as isotonic, isometric, and isokinetic.
Muscle Fiber Classification
Type 1: Slow oxidative fibers contract slowly and use aerobic respiration ( oxygen and glucose) to generate energy. This is a low power endurance fiber that is slow to fatigue.
Type 2A: Fast oxidative fibers have a fast contraction and use aerobic respiration, but can switch to anaerobic respiration (glycolysis), causing them to fatigue quicker than Type 1.
Type 2B: Fast glycolytic fibers demonstrate fast contractions and are used for anaerobic glycolysis. These fibers fatigue the quickest, but generate a large force.
Muscle Contraction Classification
Isotonic: When the muscle changes length through the exercise. There are two types of this contraction:
- Concentric: Type of contraction where the muscle shortens to generate force to overcome a load. E.g., performing a bicep curl.
- Eccentric: Type of contraction where the muscle elongates to generate force. E.g., lowering the weight after the bicep curl.
Isometric: Type of muscle contraction that generates force without changing the length of the muscle. E.g., hold up your arms for 30 seconds.
Isokinetic: Type of muscle contraction similar to isotonic but the movement is done at a constant speed under a constant resistance. E.g. breast stroke.
If you’re an athlete interested in improving your mobility and performance, contact us to learn more about our physical therapy and sports chiropractic treatments in NYC.
