Contractile properties of motor units and expression of myosin heavy chain isoforms in rat fast-type muscle after volitional weight-lifting training

Dynamic resistance training increases the force and speed of muscle contraction, but little is known about modifications to the contractile properties of the main physiological types of motor units (MUs) that contribute to these muscle adaptations. Although the contractile profile of MU muscle fiber...

Full description

Saved in:
Bibliographic Details
Published in:Journal of applied physiology (1985) 2016-10, Vol.121 (4), p.858-869
Main Authors: Łochyński, Dawid, Kaczmarek, Dominik, Mrówczyński, Włodzimierz, Warchoł, Wojciech, Majerczak, Joanna, Karasiński, Janusz, Korostyński, Michał, Zoladz, Jerzy A, Celichowski, Jan
Format: Article
Language:English
Subjects:
Adaptation, Physiological - physiology
Animals
Calcium Signaling - physiology
Endoplasmic reticulum
Exercise
Gene expression
Gene Expression Regulation - physiology
Male
Motor Neurons - physiology
Muscle Contraction - physiology
Muscle Fatigue - physiology
Muscle Fibers, Fast-Twitch - physiology
Muscle, Skeletal - cytology
Muscle, Skeletal - physiology
Myosin Heavy Chains - metabolism
Physical Conditioning, Animal - methods
Proteins
Rats
Rats, Wistar
Resistance Training - methods
Ribonucleic acid
RNA
Rodents
Volition - physiology
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Dynamic resistance training increases the force and speed of muscle contraction, but little is known about modifications to the contractile properties of the main physiological types of motor units (MUs) that contribute to these muscle adaptations. Although the contractile profile of MU muscle fibers is tightly coupled to myosin heavy chain (MyHC) protein expression, it is not well understood if MyHC transition is a prerequisite for modifications to the contractile characteristics of MUs. In this study, we examined MU contractile properties, the mRNA expression of MyHC, parvalbumin, and sarcoendoplasmic reticulum Ca pump isoforms, as well as the MyHC protein content after 5 wk of volitional progressive weight-lifting training in the medial gastrocnemius muscle in rats. The training had no effect on MyHC profiling or Ca -handling protein gene expression. Maximum force increased in slow (by 49%) and fast (by 21%) MUs. Within fast MUs, the maximum force increased in most fatigue-resistant and intermediate but not most fatigable MUs. Twitch contraction time was shortened in slow and fast fatigue-resistant MUs. Twitch half-relaxation was shortened in fast most fatigue-resistant and intermediate MUs. The force-frequency curve shifted rightward in fast fatigue-resistant MUs. Fast fatigable MUs fatigued less within the initial 15 s while fast fatigue-resistant units increased the ability to potentiate the force within the first minute of the standard fatigue test. In conclusion, at the early stage of resistance training, modifications to the contractile characteristics of MUs appear in the absence of MyHC transition and the upregulation of Ca -handling genes.
ISSN:8750-7587
1522-1601
DOI:10.1152/japplphysiol.00330.2016