Correlation between contractile strength and myosin heavy chain isoform composition in human skeletal muscle.
OBJECTIVE
The purpose of this study was to investigate the relationship between myosin heavy chain (MHC) composition and maximal contraction strength of the human quadriceps femoris muscle.


METHODS
Muscle biopsies were obtained from m. vastus lateralis in your highly physical active males (N = 7). The MHC composition of muscle homogenates was determined by electrophoresis techniques (SDS-PAGE). Isokinetic peak torque and constant-angle torque (50 degrees knee flexion) were obtained during slow (30 degrees.s-1), medium (120 degrees.s-1), and fast (240 degrees.s-1) maximal concentric and eccentric quadriceps contractions and expressed relative to muscle volume.


RESULTS
The percentage of MHC II in the quadriceps muscle was positively correlated (rs = 0.61-0.93; P < 0.05-0.01) to maximal concentric quadriceps strength obtained at medium to high knee angular velocity. In contrast, no consistent pattern of correlation was observed for maximal eccentric quadriceps strength.


CONCLUSIONS
The relationship observed between muscular MHC composition and maximal contractile strength is suggested to appear as a consequence of MHC -related differences in contractile force-velocity characteristics and/or contractile Rate of Force Development (RFD).
Aagaard
P
P
Department of Medical Physiology Panum Institute, Denmark p.aagaard@mfi.ku.dk
Andersen
J L
JL
D000328:Adult; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000737:chemistry* / Q000502:physiology*; D018995:Myosin Heavy Chains / Q000032:analysis*; D013848:Thigh
D018995:Myosin Heavy Chains