Variations in Manual Muscle Testing Affect Middle and Lower Trapezius EMG Activity

Emily Ramsay, Jasmine Lau, Thomas Komor, Jason Cherry, Denise Romano, Gurpreet Singh, Samantha Mason, Gillian Laco
Purpose:

To examine the EMG activity of the MT and LT during three MMT techniques to determine which method best isolates the targeted muscle. 


Methods:

A convenience sample of 20 individuals (12 females, 8 males) were recruited with a mean age of 32 years [22-59 years]. Participants were excluded if they had conditions affecting their shoulder or implanted devices. Inclusion criteria were being between the ages of 18-65 with normal dominant shoulder range-of-motion. Surface EMG electrodes were placed on the participant’s dominant posterior deltoid (PD), UT, MT, and LT muscles. Participants performed 3 MMT conditions for the MT and LT. The first condition was LT and MT MMT, as Kendall described. The second condition replicated the first, with the examiner providing VC to facilitate the target muscle. In the final condition, the examiner resisted the scapula while the participant was in the exact positioning described by Kendall. Three trials of each condition were performed with 2-minute breaks between trials. The normalized percentages of the MMT with VC and resistance at the scapula were compared to 100% activation using the Kendall MMTs through a one-sample t-test.




Results:

There was a significant decrease (p=.02) in maximal voluntary isometric contraction (MVIC) of the MT during MMT of the LT when VC was provided, resulting in an 88% MVIC compared to the Kendall method. There was a significant decrease in PD (73% MVIC,p.001), UT (72% MVIC,p.001), and MT (59% MVIC,p.001) during MMT of the LT when manual resistance was applied to the scapula compared to the traditional Kendall method. There were no significant differences in any muscle MVIC in MT MMT when VC was provided. There was a significant decrease (p=.002) in UT MVIC (75%) during MMT of the MT compared to the Kendall method.


Conclusion(s):

Providing resistance at the scapula during MMT of the LT and MT results in greater isolation of the LT and MT than the Kendall method. MMT of the LT with resistance at the scapula demonstrated the greatest isolation, as surrounding muscles had a decrease in MVIC. VC improved with isolation of the LT during MMT but did not affect the MMT of the MT.


Implications:

Providing manual resistance at the scapula during MMT of the MT and LT will allow clinicians to assess the targeted muscle's isolated strength.


Funding acknowledgements:
Binghamton University Division of Physical Therapy
Keywords:
Trapezius
Manual Muscle Test
Examination
Primary topic:
Musculoskeletal: upper limb
Second topic:
Orthopaedics
Did this work require ethics approval?:
Yes
Name the institution and ethics committee that approved your work:
Binghamton University
Provide the ethics approval number:
STUDY00004929
Has any of this material been/due to be published or presented at another national or international conference prior to the World Physiotherapy Congress 2025?:
No

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