Frequent Manipulation of Resistance Training Variables Promotes Myofibrillar Spacing Changes in Resistance-Trained Individuals

• Published in: Frontiers in physiology 2021-12, Vol.12, p.773995-773995
• Main Authors: Fox, Carlton D, Mesquita, Paulo H C, Godwin, Joshua S, Angleri, Vitor, Damas, Felipe, Ruple, Bradley A, Sexton, Casey L, Brown, Michael D, Kavazis, Andreas N, Young, Kaelin C, Ugrinowitsch, Carlos, Libardi, Cleiton A, Roberts, Michael D
• Format: Article
• Language: English
• Subjects: actin; muscle fiber; myofibrils; myosin; Physiology; sarcoplasm
• ISSN: 1664-042X; 1664-042X
• DOI: 10.3389/fphys.2021.773995

We sought to determine if manipulating resistance training (RT) variables differentially altered the expression of select sarcoplasmic and myofibril proteins as well as myofibrillar spacing in myofibers. Resistance-trained men (  = 20; 26 ± 3 years old) trained for 8 weeks where a randomized leg performed either a standard (CON) or variable RT protocol (VAR: manipulation of load, volume, muscle action, and rest intervals at each RT session). A pre-training (PRE) vastus lateralis biopsy was obtained from a randomized single leg, and biopsies were obtained from both legs 96 h following the last training bout. The sarcoplasmic protein pool was assayed for proteins involved in energy metabolism, and the myofibril protein pool was assayed for relative myosin heavy chain (MHC) and actin protein abundances. Sections were also histologically analyzed to obtain myofibril spacing characteristics. VAR resulted in ~12% greater volume load (VL) compared to CON (