Motor unit contractile properties and myosin heavy chain protein expression after resistance extercise

• Autorzy: Lochynski D. , Kaczmarek D. , Mrowczynski W. , Majerczak J. , Karasinski J. , Zoladz J. , Celichowski J.
• Języki publikacji: EN

Abstrakty

EN

BACKGROUND AND AIMS: Expression of distinct types of myosin heavy chain (MHC) isoforms in skeletal muscle is accepted as one of critical factors providing the molecular basis of muscle fibre functional diversity and plasticity. However, chronic nerve stimulation experiments have provided a strong evidence that modifications in the contractile regulatory and the energy metabolism systems occur much earlier than transition of myosin isoforms. METHODS: In this study we investigated expression of MHC isoforms, contractile kinetics (twitch time characteristics), force regulation (force-frequency relationship), and fatigability of motor units in rat fast-type skeletal muscle at the early stage of voluntary progressive resistance exercise program. Motor units classified into slow (S), fast resistant to fatigue (FR) and fast fatigable (FF) were functionally isolated from medial gastrocnemius muscles of rats subjected to weight lifting (WL) exercises or control, sedentary animals. RESULTS: MHC isoform expression was not changed. Shortening of the twitch contraction was observed in both types of fast MUs. The twitch half-relaxation time of FF units was prolonged in WL animals. The contraction-to-half-relaxation time ratio (twitch shape) was significantly decreased in fast MUs of WL rats. Forcefrequency curve was shifted towards higher stimulation rates in FR but not FF units. In FF MUs of WL rats force declined less in time during initial 15 seconds and then was better maintained during the next 75 seconds of performed 180-second fatigue test. In FR units of WL rats force declined more in time during the last 120 seconds of the test. S MUs contractile parameters were not changed. CONCLUSIONS: At the early stage of resistance training modifications in the contractile regulatory and energy metabolism systems of fast MUs, as acknowledged by observed alterations in their contractile kinetics and fatigability, occur before any transition in muscle MHC isoforms is observed.

• Wydawca: -
• Czasopismo: Acta Neurobiologiae Experimentalis
• Rocznik: 2015
• Tom: 75
• Numer: Supl.
• Opis fizyczny: p.S72-S73

Twórcy

autor

Lochynski D.

• Department of Neurobiology, Department of Motor Rehabilitation, University School of Physical Education, Poznan, Poland

autor

Kaczmarek D.

• Department of Biochemistry and Department of Neurobiology, University School of Physical Education, Poznan, Poland

autor

Mrowczynski W.

• Chair of Physiology and Biochemistry, Department of Muscle Physiology, University School of Physical Education, Krakow, Poland

autor

Majerczak J.

• Faculty of Rehabilitation, University School of Physical Education, Krakow, Poland

autor

Karasinski J.

• Department of Cell Biology and Imaging, Institute of Zoology, Jagiellonian University, Krakow, Poland

autor

Zoladz J.

• Faculty of Rehabilitation, University School of Physical Education, Krakow, Poland

autor

Celichowski J.

• Chair of Physiology and Biochemistry, Department of Muscle Physiology, University School of Physical Education, Krakow, Poland