Abstract details
| Abstract-ID: | 1940 |
| Title of the paper: | The effect of superimposed local vibration on isometric submaximal knee contractions |
| Authors: | TIMBERT, T., Amiez, N., Martin, A., Cometti, C., Paizis, C. |
| Institution: | University of Burgundy |
| Department: | Inserm - CAPS |
| Country: | France |
| Abstract text | INTRODUCTION: While the acute application of localised vibration (LV) at rest induces a loss of strength in most cases, it would appear that its application during contraction can prolong the duration of fatiguing exercise with a potential increase in motor unit recruitment (2). Therefore, this study investigated the effect of superimposed local vibration (SLV) to enhance strength production on submaximal knee extension. METHODS: Following a warm-up, 10 participants performed maximal voluntary isometric contractions (MVIC) and Rate of Force Development (RFD) contractions before (PRE) and after (POST) one fatiguing protocol. The protocol consists of alternating isometric contractions at 50% of the MVIC in an intermittent format (15 ON/ 5 OFF). The fatiguing task was stopped when the force produced was below 40% of the MVIC. A control condition (CON) and a condition with SLV (VIB, 100Hz, 2-3mm, quadricipital tendon) were performed in the same session, randomised, and interspersed with 45 minutes of rest. The Time Torque Integral (TTI), electromyographic activity (EMGA) of the Vastus Medialis (VL), the Vastus Lateralis (VL), and the Rectus Femoris (RF) were used to compare both fatiguing protocols. RESULTS: The fatiguing task induces a decrease in the MVIC for both conditions (p = 0.079). Similar TTI values (p = 0.100) were found for both conditions (CON: 2.38×107 ± 0.9×107 Nm.s-1 and VIB: 2.68×107 ± 1.0×107 Nm.s-1). RFD was unchanged between conditions (p = 0.913). For EMGA, no significant differences were found between conditions for either the MVIC (p > 0.070) or the fatiguing task (p > 0.184). CONCLUSION: Our study shows no change in the work produced by the two conditions or in EMGA for the quadriceps muscles. Although various studies have shown a positive effect on strength for a weak submaximal contraction (1) or sustained maximal contraction (2), our results do not support that SLV affect the ability to repeat isometric submaximal knee contractions. (1) Grande et al., “Ia afferent input alters the recruitment thresholds and firing rates of single human motor units”, Exp Brain Res, 2003. (2) Bongiovanni, et al., “Tonic vibration reflexes elicited during fatigue from maximal voluntary contractions in man”. J Physiol, 1990. |
| Topic: | Physiology |
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