Basics Of Bodybuilding Part 2

Start of this concentric contraction only a small number of motor units are activated, generating minimal force. As more force is required additional motor units are called upon. If the weight being lifted is relatively light many motor units will remain inactive only a fraction of the total muscle contracts. However, if the weight is heavy the muscle is fatigued or both the muscle must recruit as many motor unit fibers as possible to accommodate the demands being placed upon it.

The amount of force that a muscle can generate increases with the number of motor units that are utilized. For most exercises, the concentric phase comes first although on exercises such as the Squat & Bench press, you actually descend through the eccentric half to assume the real start position.

Reaching Your Peak:

At the end of the concentric contraction, a muscle is in its shortest position. Some exercise physiologists sports coaches & many bodybuilders recommend that you pause here for a second or two to contract the working muscle as intensely as possible a technique called Peak Contraction.

For example holding something like a Triceps extension at the bottom as opposed to just lightly ‘tapping’ there adds to the total Time Under Tension (TUT) which has a lot of physiological benefits in terms of activating hard-to-hit muscle fibers, establishing new neural pathways & so forth.

Others question the need to stop at any point during the rep the appropriate resistance is more important than generating a peak contraction. “If the weight is light you can never reach maximal contraction. But if you manage the resistance right you’ll get near-maximal contraction at some point during the range of motion your best bet is probably to include Peak.

Contraction as a tool without relying on it entirely to produce maximum growth stimulation. Heavy weights are better known to promote the highest levels of stimuli, activate more motor units & hence fatigue your muscles to a much greater extent than ‘peaking’ while going light.

What Goes Up Must Come Down:

Before another concentric contraction can be made again the muscle has to relax and lengthen. This happens in eccentric contraction. As you lower a dumbbell during a curl for example the bicep lengthens even though it’s still contracted to some degree. A common misconception is that a muscle contract during the first half of the movement & then relaxes as you return the weight to the start position.

In fact a muscle contracts during both phases. The difference is that the muscle shortens during the concentric half & lengthens during the eccentric half. During the eccentric phase, nerve impulses continue to signal motor units to fire even though fewer motor units are used here than during the concentric contraction. As a result, more stress is placed upon each of the activated muscle fibers.

Unfortunately, this eccentric half of the repetition many Bodybuilders mistakenly treat as an afterthought. Research confirms that the eccentric component of a lift may be just as important or even more important than the concentric phase for promoting muscle growth. What not too many are aware of is that this “Negative” portion of a rep causes more tissue breakdown & has important implications for muscle soreness and key issues in muscle-building. Since during an eccentric contraction you lower the same weight with fewer muscle fibers, each fiber involved has to sustain the greater force. Therefore a higher percentage is damaged which could lead to increased growth.