How Muscles Work

First, we must clarify how muscles work. It is too easy to descend into the world of bioscience, where the biggest guy in the gym is considered a professor and the gym his lecture hall. Time for a short biology lecture! (I know you're excited.) There are three types of muscle fibers. Type 1 muscle fibers are slow endurance fibers that have a lot of mitochondria. Thus, they are mainly used in aerobic activity. Type IIb muscle fibers are fast muscle fibers that have a very low resistance to fatigue. These fibers are mainly used for anaerobic

activities with high exertion levels. Type IIa fibers are intermediate fibers that are between type I and type IIb muscle fibers. The type IIa and IIb muscle fibers are the fibers with the most potential for growth. A muscle fiber is surrounded by a membrane with many holes in it, called transverse tubules or T-tubules. These tubules descend deep into the muscle fiber. Inside the muscle fiber, you can find the sarcoplasm (everything else besides the contractile elements of the muscle fiber) and the myofibrils. Muscle strands have thick filaments and thin filaments, which are used in muscle contraction.

their contraction and resting phases. It is not necessary to memorize the names of the bands, but realize that basically, the thick filament (red) is pulling on the thin filament (blue) to contract the muscle. Now let's examine this process in finer detail. To activate a muscle fiber, a motor neuron releases a signal into the T-tubules. This signal is then transferred to the sarcoplasmic reticulum, which releases calcium ions into the muscle. This is how the muscle cell is activated. The calcium ions bind with a myosin complex on the thin

filaments. By bonding with this complex, the tropomyosin protein that keeps the thick filament from bonding with the thin filament moves. Once the thick and thin filaments are able to bond, the thick filament can pull on the thin filaments, contracting the muscle. A muscle fiber has two states: relaxed and contracting. There is no partial muscle fiber contraction, so mammals control the force they produce by changing the number of muscle fibers that are contracting. Your body also recruits muscle fibers in a specific order, from smallest to the largest motor

neuron. Type I muscle fibers have the smallest motor neuron, with type IIa fibers having large motor neurons and type IIb fibers having very large neurons. Therefore, to activate the most muscle fibers, it's important to use near maximal loads. This is why to build muscle you use relatively low rep ranges, not ten sets of twenty reps. The main point of exceeding 15 reps when lifting weights is to increase glycogen storage in the muscle, which doesn't change the muscle itself but rather helps with endurance.

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