Effect of Motor-Control Exercises on Scapulohumeral and Scapulothoracic Muscle Activations in Athletes With Secondary Subacromial Impingement Syndrome.
Borjipour M & Taghizadeh Delkhoush C • Journal of athletic training • 2026
Scapulohumeral and scapulothoracic progressive resistance exercises reduced corresponding muscle activations during scapular arm abduction in overhead athletes with secondary subacromial impingement syndrome, while facilitatory motor-control exercises integrated into progressive resistance exercises preserved those muscle activations.
Key Findings
Results
Progressive resistance exercises (PREs) alone reduced scapulohumeral and scapulothoracic myoelectric activities during scapular arm abduction within treatment groups.
Reductions in myoelectric activity were statistically significant within groups (P ≤ .02)
Effect sizes were at least moderate (partial η² ≥ 0.127)
Measurements were taken during scapular arm abduction between 80° and 110°
Treatment was administered every other day for 8 weeks
All intervention participants also received contemporary physical therapy modalities
Results
Facilitatory biofeedback-guided motor-control exercises (MCEs) integrated into PREs preserved scapulohumeral and scapulothoracic myoelectric activities, preventing the reductions seen with PREs alone.
Preservation of muscle activations was statistically significant (P ≤ .03)
MCEs targeted specifically the infraspinatus and lower trapezius muscles
The preservation effect applied to both scapulohumeral and scapulothoracic muscle groups
Teres minor myoelectric activity was the one exception, showing no significant difference (P > .99)
Exercises were described as 'facilitatory' and 'biofeedback-guided'
Methods
The study compared three parallel groups of overhead athletes diagnosed with secondary subacromial impingement syndrome (SAIS) in a randomized controlled clinical trial design.
Participants were overhead athletes diagnosed with secondary SAIS
Three groups were used: two intervention groups and one control group
Intervention Group I received PREs integrated with facilitatory MCEs; Intervention Group II received PREs without MCEs
All groups received contemporary physical therapy modalities every other day for 8 weeks
The study was conducted at a Neuromuscular Rehabilitation Research Center
Background
Unbalanced or uncoordinated activity across scapulohumeral or scapulothoracic muscles may impair scapulohumeral rhythm during arm elevation in athletes with secondary SAIS.
Scapulohumeral rhythm during arm elevation was identified as the key biomechanical concern
Both scapulohumeral and scapulothoracic muscle groups were assessed
Myoelectric activity was the primary outcome measure recorded
The 80°–110° range of scapular arm abduction was selected as the measurement window
Secondary SAIS was the specific diagnosis used for participant inclusion
Results
Motor-control exercises specifically targeting infraspinatus and lower trapezius muscles were effective at preserving activation in most measured muscles when integrated with PREs.
Infraspinatus (scapulohumeral) and lower trapezius (scapulothoracic) were the targeted muscles for MCEs
Preservation extended beyond the directly targeted muscles to other scapulohumeral and scapulothoracic muscles
Teres minor was the only muscle that did not show a significant preservation effect (P > .99)
The MCEs were described as 'facilitatory,' suggesting an activation-enhancing approach
Integration of MCEs into PREs was the distinguishing feature between the two intervention groups
What This Means
This research suggests that in overhead athletes (such as swimmers, volleyball players, or baseball pitchers) who have a shoulder condition called secondary subacromial impingement syndrome, the type of exercise program used during rehabilitation matters significantly for how the shoulder muscles activate. The study found that standard progressive resistance exercises — where the difficulty of the exercises gradually increases over time — actually reduced the electrical activity in the shoulder blade and upper arm muscles during a key arm-raising movement. This might seem counterintuitive, as exercise is generally expected to improve muscle function, and suggests that resistance training alone may not fully address the neuromuscular coordination problems underlying this condition.
However, when motor-control exercises using biofeedback were added to the resistance training program, the muscle activations were preserved rather than reduced. These motor-control exercises specifically targeted two muscles — the infraspinatus (which helps rotate and stabilize the shoulder) and the lower trapezius (which helps control the shoulder blade) — and used biofeedback to help athletes consciously improve how they activate these muscles. The beneficial effect spread beyond just those two targeted muscles to the broader shoulder blade muscle group, with the exception of one muscle called the teres minor.
This research suggests that simply performing strengthening exercises may not be enough for overhead athletes recovering from shoulder impingement — the way muscles are coordinated and consciously activated appears to be an important factor in rehabilitation. Adding targeted motor-control and biofeedback exercises to a standard resistance training program may help maintain proper muscle activation patterns during shoulder movements, which could be relevant to designing more effective rehabilitation protocols for this population.
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Borjipour M, Taghizadeh Delkhoush C. (2026). Effect of Motor-Control Exercises on Scapulohumeral and Scapulothoracic Muscle Activations in Athletes With Secondary Subacromial Impingement Syndrome.. Journal of athletic training. https://doi.org/10.4085/1062-6050-0761.25