Research Review: Serratus Anterior Activation During Wall Slides
By Stefanie DiCarrado DPT, PT, NASM CPT & CES
Edited by Brent Brookbush DPT, PT, MS, PES, CES, CSCS, ACSM H/FS
Original Citation: Hardwick DH, Beebe JA, McDonnell MK, Lang CE. (2006). A comparison of serratus anterior muscle activation during a wall slide exercise and other traditional exercises. Journal of Orthopaedic & Sports Physical Therapy. 36(12) 903-910 - ARTICLE
The serratus anterior attaches to the anterior medial border of the scapula and to the upper 8-9 ribs. These attachments allow for protraction, posterior tilting, and upward rotation of the scapula.
Why is this relevant?: The serratus anterior (SA) is a frequently targeted muscle to rehabilitate shoulder dysfunction as it helps maintain normal scapulohumeral rhythm (1,2,3). Papers by Ludewig & Cook (2000) and Lukasiewicz et al (1999) indicated a dysfunctional serratus anterior may be related to subacromial impingement syndrome. This article compares the level of SA activation during several common rehabilitation exercises to determine how the "wall slide" exercise compares.
Study Summary
| Study Design | Single group, repeated measures |
| Level of Evidence | |
| Subject Demographics |
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| Outcome Measures |
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| Results |
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| Conclusions | All 3 exercises will activate the SA equally at 90° of arm elevation; however, previous research has suggested scapular dyskinesis occurs above 90° and therefore wall slides or scaption may be a better choice for treating common shoulder dysfunction, such as subacromial impingement syndrome. |
| Conclusions of the Researchers | SA activation during a wall slide is comparable to that of a push-up with plus and scaption at 90° of arm elevation implying that walls slides are an effective exercise selection for a shoulder rehabilitation program (particularly for subacromial impingement). |
Serratus Anterior Isolated Activation.
Review & Commentary:
Despite the small sample size (statistically determined to provide a meaningful clinical change), this research study provides strong evidence in support of exercises such as the wall slide and scaption to activate the serratus anterior (SA) with arm elevation above 90°. These findings confirm previous research by Moseley et al (1992) who found the highest EMG activity in the SA during scaption (6). The authors implemented a standardized protocol to ensure the dominant arm (R arm) was used by each subject, movement sensor and EMG electrode placement was adequately documented and described, equipment used was named and the method of movement assessment was appropriately referenced. The researchers provided sufficient references to other research studies that implemented similar protocols. To eliminate interference and cross talk, a typical limitation of surface EMG, researchers taped down and secured the movement sensors and EMG electrodes. Additionally, the researchers recorded EMG activity from the latissimus dorsi (LD) to help recognize and filter out cross talk from the electrode on the SA as it was close to the LD lateral border. Prior to testing, subjects performed a modified manual muscle test for each muscle evaluated to ensure proper electrode placement and signal to noise ratio. Subjects performed a maximal voluntary isometric contraction (MVIC) for the SA in proper MMT position (as described by Kendall et al, 1993); however, researchers explained this was only used to create % of MVIC for comparisons with other studies (7). They explained their reasons for using raw EMG data to compare each exercise rather than % of MVIC and explained each exercise in sufficient detail for future replication.
The authors used several different statistical analyses to compare the various exercises at various degrees of elevation and clearly explained the purpose of each. They did not analyze data based on age and since there was approximately a 20 year gap between the oldest and youngest, it would have been interesting to see if SA activation and muscle recruitment varied based on age of the tissue.
The researchers described the limitations of the study to be sample variation and the use of a modified push up plus. The sample did not include individuals over 40 y.o. or those with shoulder dysfunction, but the researchers do list citations where those with mild dysfunction were found to have the same activation patterns with movement. It would be interesting to repeat the study with individuals that have impingement or other shoulder dysfunction to see if the levels of recruitment differ. Researchers explained they used the push-up with plus on the wall because those with shoulder pain require this modification. The floor version has been found to allow for greater SA activation, however the authors explained that both the wall slide and the wall push up plus are typical "starting phases" for SA recruitment training and were adequate for comparison.
Future studies comparing these exercises should include EMG activity of the pectoralis minor (PMn) and further detailed evaluation of scapular movement with arm elevation. The PMn is a synergistic scapular protracter and the push up with plus exercise may prove to activate that muscle as much or even more so than the SA, rendering it inappropriate as an activation exercise for the SA.
Why is this study important?
This study is important because it validates the wall slide and scaption as appropriate exercises to activate the SA above the 90° plane, where impingement and scapular dyskinesis tend to occur.
How does it affect practice?
Clinicians looking to treat scapular or shoulder dysfunction occurring with arm elevation above 90° should consider adding scaption and/or the wall slide to their treatment plan. The authors suggested that clinicians implement scaption for individuals displaying excessive scapular elevation as the wall slide resulted in more EMG activity for the upper trapezius (UT) .
Past research has revealed decreased activation and duration of the serratus anterior in those with neck pain (see Altered Neuromuscular Activity of the Serratus Anterior in Individuals with Neck Pain ). This particular study does not mention involvement of the cervical spine but clinically, in individuals with cervical pain and dysfunction, it is crucial to include exercises that concurrently target the SA for proper rehabilitation.
How does it relate to Brookbush Institute Content?
The Brookbush Institute's predictive model of Upper Body Dysfunction (UBD) categorizes the SA as long and under-active, being reciprocally inhibited by scapular downward rotators such as the pectoralis minor (PMn) , rhomboids , and levator scapulae (LS) . Included in this model, is the upper trapezius (UT) which may present as long and under-active as it upwardly rotates the scapula along with the lower trapezius and the SA, or present as short and overactive due to its ability to anteriorly tip the scapula. As noted in the UBD write up: "Most often the upper trap is deconditioned as an upward rotator of the scapula (should be activated), and only short and overactive in the most extreme cases of UBD; in these cases the upper trap should be released." The authors of this study found increased UT activity during the wall slide, but did not describe any subsequent scapular dyskinesis that would imply how the UT may have contributed to optimal or altered scapular mechanics. This study does support the recommended serratus anterior progression by the Brookbush Institute, which includes scaption and wall slides. The videos below demonstrate serratus anterior isolated activation, wall slide progressions, and reactive integration.
Serratus Anterior Isolated Activation
Serratus Anterior Activation Progressions
Serratus Anterior Reactive Integration
Sources
1. Ekstrom RA, Bifulco KM, Lopau CJ, Andersen CF, Gough JR. (2004). Comparing the function of the upper and lower parts of the serratus anterior muscle using surface electromyography. Journal of Orthopaedic Sports Physical Therapy. 34. 235-243.
2. Inman VT, Saunders JB, Abbott LC. (1944). Observations on the functions of the shoulder joint. Journal of Bone Joint Surgery. American Volume. 26A. 1-30
3. Norkin C, Levangie P. Joint Structure and Function. A Comprehensive Analysis. Philadelphia, PA: F.A. Davis; 1983.
4. Ludewig PM, Cook TM. (2000) Alterations in shoulder kinematics and associated muscle activity in people with symptoms of shoulder impingement. Physical Therapy. 80. 276-291.
5. Lukasiewicz AC, McClure P, Michener L, Pratt N, Sennett B. (1999). Comparison of 3-dimensional scapular position and orientation between subjects with and without shoulder impingement. Journal of Orthopaedic Sports Physical Therapy 29:574-583; discussion 584-576.
6. Moseley JB, Jr., Jobe FW, Pink M, Perry J, Tibone J. EMG analysis of the scapular muscles during a shoulder rehabilitation program. Am J Sports Med. 1992;20:128- 134
7. Kendall FP, McCreary EK, Provance PG. Muscles: Testing and Function. 4th ed. Baltimore, MD: Williams & Wilkins; 1993.
© 2014 Brent Brookbush
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