How can Eccentric Contractions cause more muscle damage

How can Eccentric Contractions cause more muscle damage ?⭕️

We know that eccentric contractions tend to cause more muscle damage than concentric ones.. but how ?

Well, it turns out that when we perform hard consecutive repetitions as our muscles stretch under load, the sheer force that acts upon the sarcomeres, can disrupt them!

This first hypothesis, first introduced by Morgan DL in the ’90s, suggested that as the muscles stretch under load, the weakest sarcomeres “pop” (literally), and so do the following weak ones in the following reps. This leads to an increased number of disrupted sarcomeres, which of course reduces our ability to produce force (since less total actin-myosin cross bridges can be formed).

But that’s not all. Following this “stretch-induced injury” there’s an increased permeability of the membrane, which allows a greater amount of Calcium (Ca2+) and Sodium (Na+) influx, which trigger an inflammatory response, which leads to cellular degradation. As a result, we experience muscle damage!