Effects of different vibration frequencies, amplitudes and contraction levels on lower limb muscles during graded isometric contractions superimposed on whole body vibration stimulation

Amit N. Pujari (Corresponding Author), Richard D. Neilson, Marco Cardinale

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Abstract

Background Indirect vibration stimulation, i.e., whole body vibration or upper limb vibration, has been investigated increasingly as an exercise intervention for rehabilitation applications. However, there is a lack of evidence regarding the effects of graded isometric contractions superimposed on whole body vibration stimulation. Hence, the objective of this study was to quantify and analyse the effects of variations in the vibration parameters and contraction levels on the neuromuscular responses to isometric exercise superimposed on whole body vibration stimulation. Methods In this study, we assessed the ‘neuromuscular effects’ of graded isometric contractions, of 20%, 40%, 60%, 80% and 100% of maximum voluntary contraction, superimposed on whole body vibration stimulation (V) and control (C), i.e., no-vibration in 12 healthy volunteers. Vibration stimuli tested were 30 Hz and 50 Hz frequencies and 0.5 mm and 1.5 mm amplitude. Surface electromyographic activity of the vastus lateralis, vastus medialis and biceps femoris were measured during V and C conditions with electromyographic root mean square and electromyographic mean frequency values used to quantify muscle activity and their fatigue levels, respectively. Results Both the prime mover (vastus lateralis) and the antagonist (biceps femoris) displayed significantly higher (P < 0.05) electromyographic activity with the V than the C condition with varying percentage increases in EMG root-mean-square (EMGrms) values ranging from 20% to 200%. For both the vastus lateralis and biceps femoris, the increase in mean EMGrms values depended on the frequency, amplitude and muscle contraction level with 50 Hz–0.5 mm stimulation inducing the largest neuromuscular activity. Conclusions These results show that the isometric contraction superimposed on vibration stimulation leads to higher neuromuscular activity compared to isometric contraction alone in the lower limbs. The combination of the vibration frequency with the amplitude and the muscle tension together grades the final neuromuscular output.
Original languageEnglish
Number of pages23
JournalJournal of Rehabilitation and Assistive Technologies Engineering
Volume6
DOIs
Publication statusPublished - Jan 2019

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Isometric Contraction
Vibration
Lower Extremity
Muscles
Quadriceps Muscle
Neuromuscular Agents
Exercise Therapy
Muscle Tonus
Muscle Contraction
Upper Extremity
Fatigue
Healthy Volunteers
Exercise

Keywords

  • Vibration stimulation
  • electromyography
  • neuromuscular response
  • isometric contraction
  • co-contraction

Cite this

@article{4178c417b16c4cf0a9751da9d267b6f2,
title = "Effects of different vibration frequencies, amplitudes and contraction levels on lower limb muscles during graded isometric contractions superimposed on whole body vibration stimulation",
abstract = "Background Indirect vibration stimulation, i.e., whole body vibration or upper limb vibration, has been investigated increasingly as an exercise intervention for rehabilitation applications. However, there is a lack of evidence regarding the effects of graded isometric contractions superimposed on whole body vibration stimulation. Hence, the objective of this study was to quantify and analyse the effects of variations in the vibration parameters and contraction levels on the neuromuscular responses to isometric exercise superimposed on whole body vibration stimulation. Methods In this study, we assessed the ‘neuromuscular effects’ of graded isometric contractions, of 20{\%}, 40{\%}, 60{\%}, 80{\%} and 100{\%} of maximum voluntary contraction, superimposed on whole body vibration stimulation (V) and control (C), i.e., no-vibration in 12 healthy volunteers. Vibration stimuli tested were 30 Hz and 50 Hz frequencies and 0.5 mm and 1.5 mm amplitude. Surface electromyographic activity of the vastus lateralis, vastus medialis and biceps femoris were measured during V and C conditions with electromyographic root mean square and electromyographic mean frequency values used to quantify muscle activity and their fatigue levels, respectively. Results Both the prime mover (vastus lateralis) and the antagonist (biceps femoris) displayed significantly higher (P < 0.05) electromyographic activity with the V than the C condition with varying percentage increases in EMG root-mean-square (EMGrms) values ranging from 20{\%} to 200{\%}. For both the vastus lateralis and biceps femoris, the increase in mean EMGrms values depended on the frequency, amplitude and muscle contraction level with 50 Hz–0.5 mm stimulation inducing the largest neuromuscular activity. Conclusions These results show that the isometric contraction superimposed on vibration stimulation leads to higher neuromuscular activity compared to isometric contraction alone in the lower limbs. The combination of the vibration frequency with the amplitude and the muscle tension together grades the final neuromuscular output.",
keywords = "Vibration stimulation, electromyography, neuromuscular response, isometric contraction, co-contraction",
author = "Pujari, {Amit N.} and Neilson, {Richard D.} and Marco Cardinale",
note = "Acknowledgements The authors would like to thank Scottish Funding Council (SFC) for funding to support the study. The authors thank the volunteers for their participation. ANP would also like to thank Royal Society of Edinburgh for the J M Lessells Travelling Fellowship and to Prof. Kevin Englehart of University of New Brunswick, Canada for his expert advice during the fellowship in relation to this work. Funding The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Scottish Funding Council’s North of Scotland Technology (NESTech) Seed Fund. ANP was also supported by a Royal Society of Edinburgh’s J M Lessells Travelling Fellowship in relation to this work.",
year = "2019",
month = "1",
doi = "10.1177/2055668319827466",
language = "English",
volume = "6",
journal = "Journal of Rehabilitation and Assistive Technologies Engineering",
issn = "2055-6683",
publisher = "SAGE Publications Ltd STM",

}

TY - JOUR

T1 - Effects of different vibration frequencies, amplitudes and contraction levels on lower limb muscles during graded isometric contractions superimposed on whole body vibration stimulation

AU - Pujari, Amit N.

AU - Neilson, Richard D.

AU - Cardinale, Marco

N1 - Acknowledgements The authors would like to thank Scottish Funding Council (SFC) for funding to support the study. The authors thank the volunteers for their participation. ANP would also like to thank Royal Society of Edinburgh for the J M Lessells Travelling Fellowship and to Prof. Kevin Englehart of University of New Brunswick, Canada for his expert advice during the fellowship in relation to this work. Funding The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Scottish Funding Council’s North of Scotland Technology (NESTech) Seed Fund. ANP was also supported by a Royal Society of Edinburgh’s J M Lessells Travelling Fellowship in relation to this work.

PY - 2019/1

Y1 - 2019/1

N2 - Background Indirect vibration stimulation, i.e., whole body vibration or upper limb vibration, has been investigated increasingly as an exercise intervention for rehabilitation applications. However, there is a lack of evidence regarding the effects of graded isometric contractions superimposed on whole body vibration stimulation. Hence, the objective of this study was to quantify and analyse the effects of variations in the vibration parameters and contraction levels on the neuromuscular responses to isometric exercise superimposed on whole body vibration stimulation. Methods In this study, we assessed the ‘neuromuscular effects’ of graded isometric contractions, of 20%, 40%, 60%, 80% and 100% of maximum voluntary contraction, superimposed on whole body vibration stimulation (V) and control (C), i.e., no-vibration in 12 healthy volunteers. Vibration stimuli tested were 30 Hz and 50 Hz frequencies and 0.5 mm and 1.5 mm amplitude. Surface electromyographic activity of the vastus lateralis, vastus medialis and biceps femoris were measured during V and C conditions with electromyographic root mean square and electromyographic mean frequency values used to quantify muscle activity and their fatigue levels, respectively. Results Both the prime mover (vastus lateralis) and the antagonist (biceps femoris) displayed significantly higher (P < 0.05) electromyographic activity with the V than the C condition with varying percentage increases in EMG root-mean-square (EMGrms) values ranging from 20% to 200%. For both the vastus lateralis and biceps femoris, the increase in mean EMGrms values depended on the frequency, amplitude and muscle contraction level with 50 Hz–0.5 mm stimulation inducing the largest neuromuscular activity. Conclusions These results show that the isometric contraction superimposed on vibration stimulation leads to higher neuromuscular activity compared to isometric contraction alone in the lower limbs. The combination of the vibration frequency with the amplitude and the muscle tension together grades the final neuromuscular output.

AB - Background Indirect vibration stimulation, i.e., whole body vibration or upper limb vibration, has been investigated increasingly as an exercise intervention for rehabilitation applications. However, there is a lack of evidence regarding the effects of graded isometric contractions superimposed on whole body vibration stimulation. Hence, the objective of this study was to quantify and analyse the effects of variations in the vibration parameters and contraction levels on the neuromuscular responses to isometric exercise superimposed on whole body vibration stimulation. Methods In this study, we assessed the ‘neuromuscular effects’ of graded isometric contractions, of 20%, 40%, 60%, 80% and 100% of maximum voluntary contraction, superimposed on whole body vibration stimulation (V) and control (C), i.e., no-vibration in 12 healthy volunteers. Vibration stimuli tested were 30 Hz and 50 Hz frequencies and 0.5 mm and 1.5 mm amplitude. Surface electromyographic activity of the vastus lateralis, vastus medialis and biceps femoris were measured during V and C conditions with electromyographic root mean square and electromyographic mean frequency values used to quantify muscle activity and their fatigue levels, respectively. Results Both the prime mover (vastus lateralis) and the antagonist (biceps femoris) displayed significantly higher (P < 0.05) electromyographic activity with the V than the C condition with varying percentage increases in EMG root-mean-square (EMGrms) values ranging from 20% to 200%. For both the vastus lateralis and biceps femoris, the increase in mean EMGrms values depended on the frequency, amplitude and muscle contraction level with 50 Hz–0.5 mm stimulation inducing the largest neuromuscular activity. Conclusions These results show that the isometric contraction superimposed on vibration stimulation leads to higher neuromuscular activity compared to isometric contraction alone in the lower limbs. The combination of the vibration frequency with the amplitude and the muscle tension together grades the final neuromuscular output.

KW - Vibration stimulation

KW - electromyography

KW - neuromuscular response

KW - isometric contraction

KW - co-contraction

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DO - 10.1177/2055668319827466

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