Changes of motor unit contractile properties after long-term exposure to the whole-body vibration in the rat

• Autorzy: Krutki P. , Kaczmarek D. , Lochynski D. , Celichowski J.
• Języki publikacji: EN

Abstrakty

EN

Whole-body vibration (WBV) evokes increased activity of motor units (MUs) what is attributed to the enhanced afferent feedback and descending drive to the motoneuronal pool. In comparison to voluntary contractions, high-threshold MUs are more effectively activated during WBV due to lower recruitment thresholds of MUs during reflex contractions induced by mechanical vibration. Therefore WBV has been proposed to be a specific training for fast-twitch muscle fibers. Indeed, a 5-week WBV has been previously shown to induce the considerable increase of twitch and tetanic forces of FF MUs. The aim of the present study was to determine long-term effects of WBV on MU contractile properties. Two groups of Wistar rats were trained on the vibratory platform (Power Plate, USA) for 3 months or 6 months (4×30 s daily, at 50 Hz frequency, the peak-to-peak amplitude of 2.5 mm, the maximum acceleration of the platform 4.79 g). Results were compared to two control groups of normally active rats (matched with respect to age and body weight). Contractile properties were measured from functionally isolated MUs of the medial gastrocnemius muscle. Contrary to effects of short exposure to WBV, the long-term WBV did not changed significantly force parameters of FF units, only minor tendencies for an increase of tetanic forces of FF units were found after 3 or 6 months of WBV. It seems that effects of the WBV are temporary in FF MUs that adapt to longterm vibration stimuli. On the other hand, lower twitch forces, higher tetanic forces and a significant decrease of the twitch-totetanus force ratios were observed for FR and S MUs. Moreover, changes in proportion of fast MUs were observed after 3 and 6 months of WBV: the increase of a relative number of FF and the decrease of FR units. This suggests that the long-term WBV induces deeper processes that influence mechanisms of MU contraction (e.g., altered myosin heavy-chain expression or changed properties of motoneurones).

• Wydawca: -
• Czasopismo: Acta Neurobiologiae Experimentalis
• Rocznik: 2011
• Tom: 71
• Numer: S
• Opis fizyczny: p.81-82

Twórcy

autor

Krutki P.

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

autor

Kaczmarek D.

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

autor

Lochynski D.

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

autor

Celichowski J.

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

Uwagi

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