Neck Muscle Synergy During Arm Raise Exercises in Individuals With

Chronic Neck Pain of a Traumatic and Non-Traumatic Onset

Curtis SA1, Kallenberg LAC2, Burridge JH1

1 University of Southampton, Southampton, UK2 Roessingh Research and Development, Enschede, The

Netherlands

E-mail: S.A.Curtis@southampton.ac.uk

Aim of the study

To determine whether muscle activity differed in individuals

with chronic neck pain in the upper trapezius (UTRP) and

sternocleidomastoid (SCM) muscles during a sustained arm

raise task.

Subjects:• Traumatic onset (TO, n =4)

• Non-traumatic onset (NTO, n =13)

• Healthy controls (HC, n =18)

Method

Projected line

Relaxed hand position

Subjects performed bilateral shoulder abduction and maintained

the position until fatigue resulted in the arms dropping below 90o.

Method

Simultaneous recordings of the UTRPs and SCMs were obtained

using 4 x 4 linear array electrodes

After Hermens & Freriks (1999). After Falla et al. (2002).

Method – Array electrodes

Data

RUTRP

LUTRP

RSCM

LSCM

Channels 1-3

Channels 5-7

Channels 9-11

Channels 13-15

The UTRPs were directly recruited in the arm raise activity. The SCMs could be recruited to stabilise the arm

raise position.

Signal processing

Wavelet template

MUAP identified on

three consecutive

channels

Motor unit action potentials (MUAPs) were detected from the recorded signals using an algorithm based on

the Continuous Wavelet Transform.

Parameters measured•Global root-mean-square (GRMS)

•Motor unit action potential root-mean-square

(MRMS)

•Motor unit action potential rate (MR), the number

of MUAPs per second

The above parameters were estimated and changes over time, as well as differences between the groups, were investigated.

Results – right upper trapezius

Lower MRMS (p<0.042) and higher MR (p< 0.075) were seen in the TO group compared to the HC and NTO groups.

µVµV

Epoch Epoch Epoch

Global RMS (GRMS) MUAP RMS (MRMS) MUAP RATE (MR)

Results – left upper trapezius

A trend for lower MRMS (p<0.134) and higher MR values (p<0.011)

were seen in the TO group compared to the HC and NTO groups.

µV

µV

Epoch Epoch Epoch

Global RMS (GRMS) MUAP RMS (MRMS) MUAP RATE (MR)

Results – right sternocleidomastoid

The TO group showed lower values for GRMS (p<0.027),

MRMS (p< 0.042) and a trend for lower MR values (p<0.184) as compared to the HC and NTO groups.

µV

µV

Epoch Epoch Epoch

µV

Epoch Epoch

Global RMS (GRMS) MUAP RMS (MRMS) MUAP RATE (MR)

µV

Results – right sternocleidomastoid

The TO group showed lower values for GRMS (p<0.027),

MRMS (p< 0.042) and a trend for lower MR values (p<0.184) as compared to the HC and NTO groups.

µV

µV

Epoch Epoch Epoch

µV

µV

Epoch EpochEpoch

Global RMS (GRMS) MUAP RMS (MRMS) MUAP RATE (MR)

Conclusions• The lower MRMS and higher MR values in the

UTRPS (TO group) suggest a greater proportion of small, low-threshold MUs activated more frequently.

• Increasing SCM activity was seen in all groups, possibly to help stabilise the arm raise position when the muscles directly involved became fatigued.

• However, reduced GRMS, MRMS and MR values seen in the TO group in the right SCM suggest they did not employ this muscle as much as the HC and NTO groups.

References• Falla, D., Dall'Alba, P., Rainoldi, A., Merletti, R., &

Jull, G. 2002b, Location of innervation zones of sternocleidomastoid and scalene muscles - a basis for clinical and research electromyography applications., Clinical Neurophysiology, vol. 113, pp. 57-63.

• Hermens, H. J., & Freriks, B. 1999, European recommendations for surface electromyography. Results of the SENIAM project. Roessingh Research and Development b.v., ISBN: 90-75452-14-4. (CD-ROM).

Acknowledgements

I would like to thank

Gerald Kerkut Trust

and the School of Health Sciences

(University of Southampton)

for their generous support of this project