Home > Riviste > The Journal of Sports Medicine and Physical Fitness > Fascicoli precedenti > Articles online first > The Journal of Sports Medicine and Physical Fitness 2020 Oct 22

ULTIMO FASCICOLO
 

JOURNAL TOOLS

eTOC
Per abbonarsi PROMO
Sottometti un articolo
Segnala alla tua biblioteca
 

ARTICLE TOOLS

Publication history
Estratti
Permessi
Per citare questo articolo

 

 

The Journal of Sports Medicine and Physical Fitness 2020 Oct 22

DOI: 10.23736/S0022-4707.20.10469-9

Copyright © 2020 EDIZIONI MINERVA MEDICA

lingua: Inglese

Myosin heavy chain expression relationships to power-load and velocity-load curves

Michael T. LANE 1 , Andrew C. FRY 2

1 Exercise Physiology Laboratory, Eastern Kentucky University, Richmond, KY, USA; 2 Osness Human Performance Laboratories, University of Kansas, Lawrence, KS, USA


PDF


BACKGROUND: Velocity- and power-based training are popular methods of determining training session loads and volumes. One factor that may influence load-velocity and load-power properties of an individual is the myosin heavy chain (MHC) composition of the muscle.
PURPOSE: To examine the relationship between MHC composition and both load-velocity and load-power properties of muscle performance.
METHODS: 42 Men with a variety of training backgrounds took part in this study ( ±SD; age=22.4±3.5 yrs, hgt=1.78±0.07 m, BW=78.7±13.3 kg). After testing leg extension one repetition maximum (1 RM), subjects performed maximal effort leg extensions at loads from 30% - 90% 1 RM. Muscle biopsies from the vastus lateralis were analyzed via SDS-PAGE electrophoresis technique for MHC content (IIx=13.8±12.9%, IIa=49.4±10.3%, I=36.8±11.3%). Leg extension rotational velocity and power were plotted against relative loads for all subjects.
RESULTS: Significant correlations (p<.05) were observed for MHC IIa with all performance variables (i.e., slopes, intercepts, peaks and relative loads). Relationships indicated that greater %MHC IIa was associated with greater velocity intercepts, more negative load-velocity slopes, greater maximal power, and with maximal power occurring at a lower relative intensity (% 1 RM).
CONCLUSIONS: These data indicate that muscle velocity and power characteristics appear to be partially influenced by MHC content in a manner consistent with single muscle fiber contractile properties.


KEY WORDS: Skeletal muscle; Fiber type; Leg extension; Kinetics; Kinematics

inizio pagina