Research Report Abstracts - Gesundheit

WPT2011, Research Report Abstracts eS467
older adult patients; however, what influenced their confidence
was not identified and warrants further investigation.
In addition, the more important therapists believed HP was,
the more likely they were to incorporate it into their practice.
In this study, geographical location, work experience, and
level of education did not appear to influence PTs’ practice
of HP.
Implications: Given the obesity epidemic and increasing
numbers of older adults, it’s alarming that physical fitness
was not addressed more often during PT-patient encounters.
The growing numbers of at-risk children and older adults
around the world may benefit from PTs learning how to better
implement a holistic approach to HP in their clinical practice.
Keywords: Health promotion; Survey; Lifespan
Funding acknowledgements: None.
Ethics approval: IRB approval was obtained from Northwestern
University.
Research Report Poster Display
Number: RR-PO-303-7-Thu Thursday 23 June 13:00
RAI: Exhibit Halls 2&3
DETERMINING PEAK EMG AMPLITUDE OF THE
TRICEPS SURAE MUSCLES DURING MAXIMUM
VOLUNTARY ISOMETRIC CONTRACTION:
WHICH POSITION IS BEST FOR WHICH MUSCLE?
Hebert-Losier K. 1 , Schneiders A.G. 1 , Sullivan S.J. 1 , Garcia
J.A. 2 , Simoneau G.G. 3
1University of Otago, School of Physiotherapy, Dunedin,
New Zealand, 2University of Otago, Preventive and Social
Medicine, Dunedin, New Zealand, 3Marquette University,
Department of Physical Therapy, Milwaukee, United States
Purpose: To determine which knee position during maximum
voluntary isometric contraction (MVIC) elicits peak
EMG amplitudes for soleus (SOL), gastrocnemius medialis
(GM) and gastrocnemius lateralis (GL).
Relevance: Normalisation of EMG signals to peak EMG
amplitudes elicited by MVIC is common practice in physical
therapy research. The peak activities of the triceps surae
(TS) muscles are currently acquired during plantar-flexion
MVICs performed in various knee positions; which are suggested
to selectively activate gastrocnemius and/or soleus.
While inferred muscle selectivity has construct validity primarily
based on anatomical and physiological premises, there
is only limited research on the actual amplitudes of TS muscle
activity during MVIC performed in different knee positions.
Participants: Forty-eight healthy males and females (18–45
years).
Methods: Participants performed three 3 seconds MVIC trials
with their dominant lower-limb in each of the following
positions: 1. Standing 0 ◦ knee flexion; 2. Standing 45 ◦ knee
flexion; 3. Sitting 90 ◦ knee flexion. Surface EMG signals for
SOL, GM and GL were collected using a Noraxon TeleMyo
2400 T G2 TM device.
Analysis: Peak root-mean-square (rms) amplitudes were calculated
in 250 milliseconds epochs from each MVIC trial.
The trials which elicited the highest rms amplitudes for each
muscle were retained and tabulated in contingency tables
according to knee position. Chi-square tests were used to
determine if the counts were similar across positions, considering
the repeated-measures design of the study.
Results: There was a significant difference in the number
of times the positions generated the highest peak rms amplitudes
for each TS muscle (p < .001). Positions (1), (2), and
(3) respectively provided 75%, 21% and 4% of the highest
rms amplitudes for GM; 65%, 27% and 8% for GL; and 42%,
56% and 2% for SOL. All TS muscles considered, the sitting
position (3) only generated 5% of the highest rms amplitudes
compared to 95% in standing (1) (2). Analyses demonstrated
that while standing with 0 ◦ knee flexion compared to 45 ◦
more frequently generated the highest rms amplitudes for GM
(p < .001) and for GL (p = .007); no difference was observed
for SOL (p = .307).
Conclusions: None of the three investigated knee positions
consistently captured the peak EMG amplitudes of the
TS muscles during MVIC, with sitting seldom generating
the highest amplitudes. Researchers are advised to perform
MVIC of the TS muscles in standing 0 ◦ and 45 ◦ knee flexion.
The peak activity of soleus is not selectively elicited in 90 ◦
knee flexion, nor is the peak gastrocnemius activity in 0 ◦ .
Implications: Employing different knee flexion positions in
standing is optimal for determining peak TS muscle activity
during MVIC, whereas sitting is considered ineffective
even for soleus. The knowledge will assist in future EMG
research and help to refine the physical therapeutic evaluation,
rehabilitation, training, and development of injury
prevention strategies specific to the TS muscles.
Keywords: Triceps surae muscles; Surface electromyography;
Maximum voluntary isometric contraction
Funding acknowledgements: School of Physiotherapy
Mark Steptoe Trust Fund.
Ethics approval: University of Otago Human Ethics Committee.