Properties of rhythmic firing of motoneurons are altered in response to weight-lifting training in rats

• Autorzy: Krutki P. , Mrowczynski W. , Baczyk M. , Lochynski D. , Celichowski J.
• Języki publikacji: EN

Abstrakty

EN

INTRODUCTION: Repeated short-term and high--intensity exercises with a progressive external load are defined as strength or resistance training, which is responsible for an increase in muscle mass and force. AIM(S): The aim of this study was to determine whether strength training induces adaptive changes in firing properties of motoneurons (MNs) innervating the trained muscles. METHOD(S): The study was performed on adult male Wistar rats. Animals from the training group were subjected to a five‑week voluntary progressive weight‑lifting program, while control rats were restricted to standard cage activity. Intracellular recordings from lumbar spinal MNs innervating gastrocnemius and soleus muscles were made under pentobarbital anesthesia. RESULTS: The strength training evoked adaptive changes in both slow and fast-type MNs, indicating their increased excitability: a higher input resistance, a lower rheobase, a decrease in the minimum currents required to evoke rhythmic firing. The maximum frequencies of the early‑state firing (ESF) and of the steady‑state firing (SSF) were increased. Moreover, higher ESF and SSF slopes of the frequency-current relationship were observed in MNs of the trained group. Higher maximum firing rates of MNs as well as higher discharge frequencies evoked at the same level of intracellular depolarization current imply higher levels of tetanic forces developed by motor units over the operating range of force production after the strength training. CONCLUSIONS: This study provides evidence that the changes in spinal excitability following strength training observed in humans may be due to changes in the intrinsic properties of the MNs. The findings largely explain why some adaptations in the twitch and tetanus force development of motor units could be observed in response to the dynamic resistance training without qualitative changes in the muscle myosin heavy-chain expression. FINANCIAL SUPPORT: The study was supported by the National Science Center grant 2013/11/B/NZ7/01518.

• Wydawca: -
• Czasopismo: Acta Neurobiologiae Experimentalis
• Rocznik: 2017
• Tom: 77
• Numer: Suppl.1
• Opis fizyczny: p.81

Twórcy

autor

Krutki P.

• Department of Neurobiology, Poznan University of Physical Education, Poznan, Poland

autor

Mrowczynski W.

• Department of Neurobiology, Poznan University of Physical Education, Poznan, Poland

autor

Baczyk M.

• Department of Neurobiology, Poznan University of Physical Education, Poznan, Poland

autor

Lochynski D.

• Department of Musculoskeletal Rehabilitation, Poznan University of Physical Education, Poznan, Poland

autor

Celichowski J.

• Department of Neurobiology, Poznan University of Physical Education, Poznan, Poland