Audio Abstracts are changing the way scientific research is being communicated. WatchMartino’s video below where he delves into his article ‘Architectural, Functional and Molecular Responses to Concentric and Eccentric Loading in Human Skeletal Muscle’, highlighting the purpose of the study, its limitations and the practical applications. If you want to read the abstract or access the full paper (where available), all links are below.

The full paper can be found on Researchgate

Martino can be found on Twitter @MVFranchi

Abstract: We investigated architectural, functional, and molecular responses of human skeletal muscle to concentric (CON) or eccentric (ECC) resistance training (RT). Twelve young males performed 10 weeks of concentric (CON) or eccentric (ECC) resistance training (RT) (n = 6 CON, 6 ECC). An additional 14 males were recruited to evaluate acute muscle fascicle behaviour and molecular signalling in biopsies collected from vastus lateralis (VL) after 30 min of single bouts of CON or ECC exercise. VL volume was measured by magnetic resonance imaging. Muscle architecture (fascicle length, Lf; pennation angle, PA) was evaluated by ultrasonography. Muscle remodelling signals to CON or ECC loading (MAPK/AKT-mammalian target of rapamycin (mTOR) signalling) and inflammatory pathway (TNFα/Murf-1-MAFbx) were evaluated by immunoblotting. Despite the ~1.2 fold greater load of the ECC group, similar increases in muscle volume (+8% CON and +6% ECC) and in maximal voluntary isometric contraction (+9% CON and +11% ECC) were found after RT. However, increases in Lf were greater after ECC than CON (+12 vs. +5%) while increases in PA were greater in CON than ECC (+30 vs. +5%). Distinct architectural adaptations were associated with preferential growth in the distal regions of VL for ECC (+ECC +8% vs. +CON +2) and mid-belly for CON (ECC +7 vs. CON +11%). While MAPK activation (p38MAPK, ERK1/2, p90RSK) was specific to ECC, neither mode affected AKT-mTOR or inflammatory signalling 30 min after exercise. Muscle growth with CON and ECC RT occurs with different morphological adaptations reflecting distinct fibre fascicle behaviour and molecular responses.