All muscle contractions are equally important for muscle growth. Overloading the eccentric component results in more muscle damage and soreness at first. The muscle then protects itself from further damage through the repeated bout effect. After that, muscle damage and soreness are diminished. If you incorporate heavy eccentric exercise into your routine, you will probably need to reduce your workout frequency to accommodate the excess muscle damage and soreness.
CONCENTRIC VS ECCENTRIC EXERCISE FOR GAINING MUSCLE SUMMARY
- There is no superiority of eccentric exercise compared to concentric contractions when high levels of effort or the sets are taken to failure.·
- Muscle damage becomes less over time due to the repeated bout effect, but muscle growth still occurs.
- Excess muscle damage can reduce muscle growth.
- When using the same amount of weight, concentric contractions (lifting the weight) are highly fatiguing, whereas eccentric contractions (lowering the weight) are relatively fatigue-resistant.
- Muscle growth can occur with both heavy and light weight, independent of the load.
THE TYPES OF CONTRACTIONS THAT CAN INFLUENCE MUSCLE GROWTH: CONCENTRIC VS ECCENTRIC EXERCISE
Repetitions are further broken down into three components: a concentric phase (concentric meaning lifting the weight), an isometric phase (muscle contracting, but no joint movement is occurring), and an eccentric phase (eccentric meaning lowering the weight). The difference between concentric and eccentric exercises is during the concentric phase, the muscle shorts, whereas during the eccentric phase, the muscle is lengthened or stretched.
If you were using the leg extension, the lift would begin with a concentric phase in which the weight is lifted. The isometric phase is when the weight is paused in the middle of the movement, and finally, the eccentric phase is when the weight is lowered.
Isometric exercise places tension on the muscle, but the active contracting and stretching of muscle results in superior muscle growth. It’s not uncommon to see people in the gym lifting a weight with no control; however, it’s important to understand that tension and tension duration on the muscle are much more important than the weight.
This means that a maximal lift lasting a few seconds will be inferior to muscle growth using a lesser weight but more tension on a muscle over a longer duration. Researchers found that when subjects trained with 75% of a maximal voluntary contraction, sustained muscle contractions in the leg extension (contracted the legs explosively for 1 sec but held the contraction for 3 seconds) resulted in more than a 3-fold greater increase in muscle growth than explosive contractions (contracting as hard and as fast as possible). This shows that muscle growth depends on the weight and loading duration (i.e., time).
This simple study is a good analogy for muscle growth responses between powerlifting and bodybuilding protocols. Powerlifting protocols use peak tension for a short time frame, whereas bodybuilding protocols result in greater sustained tension for a more prolonged period.
Isometric exercise places tension on the muscle, but no active stretch will result in lesser muscle growth than actively contracting the muscle. You expose different muscle fibers to various external stressors by actively stretching and contracting the muscle.