What are the muscle fiber characteristics of Olympic lifters?

for full article click here What are the muscle fiber characteristics of Olympic lifters?

A great deal of research has been performed in relation to muscle fiber type indifferent athletes and in different muscle groups. In most cases, strength and power athletes are grouped into one category for analysis.

On Monday, I reviewed the muscle fiber types of powerlifters. But what do we know about the muscle fiber types of competitive Olympic lifters? This study set out to find out…

The study: Muscle Fiber Characteristics and Performance Correlates of Male Olympic-Style Weightlifters, by Fry, Schilling, Staron, Hagerman, Hikida, and Thrush, in Journal of Strength and Conditioning Research, 2003

What is the background?

Muscular adaptations to resistance exercise are well-known to occur. They include changes in physiological cross-sectional area, muscle fiber type, fascicle length and pennation angle, as well as the ability to produce increased force. Additionally, while endurance training appears to lead to an increased degree of muscle capillarization, some researchers have reported that resistance training results in reduced muscle capillarization because of the larger muscle fiber cross-sectional areas.

Muscle fiber type can be assessed by using myosin adenosine triphosphatase (mATPase) histochemistry, and researchers generally classify fibers along a continuum of fiber types from 1 to 1/IIA to IIA to IIA/X to IIX, where type IIX was previously referred to as type IIB. It is thought that the contraction speed of the muscle fibers may correlate with the type, with type I fibers contracting most slowly and type IIX fibers most quickly.

Although type IIX fibers are thought to be the most beneficial for power, resistance training generally leads to a shift in fiber type in the direction of type IIA from type IIX. It appears that any resistance training causes the muscles to adapt in ways to allow them to endure the strenuous training sessions.

Upon taking a break from resistance training, this shifting in type IIX to IIA fiber type reverses, possibly allowing speed and power athletes to produce even greater power outputs temporarily. Detraining can actually cause an overshoot of type IIX fibers, meaning that the proportion of type IIX fibers reaches a greater level following a period of training and then detraining compared to baseline values (see Anderson and Aagaard, 2010). There is little if any indication that any shift from type I to type II fibers occurs as a result of training.

Additionally, the presence of different titin isoforms may lead to differences in muscular performance. Titin is an elastic structural protein, which contributes to the passive and active force–producing capabilities of skeletal muscle. There are two isoforms of titin and each isoform is associated with different force-producing capabilities that could influence the stored elastic energy of muscle.

Given the importance of the stretch-shortening cycle in Olympic weightlifting, it is possible that differences in titin isoforms could be observed between the Olympic weightlifters and controls. However, whether titin isoforms alter with resistance training is currently unclear.

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