Updated: Nov 21, 2022
Helder, so I had time to think and make notes on the concentric training, can we look into the eccentric?
Sure, so when a muscle fibres lengthen, they produce force because of active and passive elements inside them. Last time I told you about the active elements, so now I will tell you about the passive.
Passive elements are elastic structures that exert force by resisting being deformed, rather than by using energy to move. This means the muscle fibre can exert higher forces in lowering the weight, compared to when we lift a weight.
Does that mean I am stronger when lowering a weight?
Yes, around 20-30% stronger than when lifting a weight in the same exercise.
Why does this happen?
Most likely because the muscle is being tested during electrical stimulation rather than a voluntary movement, in which the central nervous system will limit how much force we can exert, as safety mechanism.
So when I lift the weight, the muscle bulges, why does this not happen when I am lowing the weight?
As a muscle fibre produces force on lowering the weight, the actin and myosin myofilaments I mentioned in the last talk experience progressively less and less overlap and this is why they do not bulge outwards. Since the muscle fibre does not change in volume, they actually reduce in diameter as they increase in length.
Does the muscle deform as it does when we lift it?
Yes, but more longitudinal rather than outward, which also stimulates muscle growth.
The take way from the conversations on eccentric and concentric training
The lifting phase of an exercise (concentric), and the lowering phase of an exercise (eccentric) both lead to similar increases in muscular fibre volume (size).
The lowering phase causes greater gains in fibre length, as well as greater increases in the size of the distal region of the muscle.
The lifting phase causes greater increases in fibre diameter, as well as greater increases in the middle range of the muscle.
They are both as important as each other and we must make sure each exercise is performed with this in mind.