Related Experiment Video
Updated: Jun 19, 2026
10:07
Measurement of Dynamic Scapular Kinematics Using an Acromion Marker Cluster to Minimize Skin Movement Artifact
Published on: February 10, 2015
Quantifying scapula orientation and its influence on maximal hand force capability and shoulder muscle activity
Bryan R Picco1, Steven L Fischer, Clark R Dickerson
1Department of Kinesiology, University of Waterloo, Waterloo, Canada.
Clinical Biomechanics (Bristol, Avon)
|October 24, 2009
Summary
Neutral scapular orientation balances muscle use for reduced injury risk. Downward exertions may enhance force production and lower muscle activity, supporting clinical recommendations for shoulder health.
Area of Science:
- Biomechanics
- Human Movement Science
- Orthopedics
Background:
- Non-neutral scapular orientations are frequently linked to shoulder pathologies.
- The precise impact of scapular orientation on shoulder functional capabilities remains under-researched.
Purpose of the Study:
- To objectively measure scapular orientation.
- To quantify the influence of scapular orientation on shoulder muscle activity and hand force during manual exertions.
Main Methods:
- Ten healthy males performed exertions in varied scapular orientations (protracted, neutral, retracted) and directions.
- Scapular orientation was measured using an acromion marker cluster method.
- Statistical analyses (ANOVA) assessed the effects of orientation and exertion on muscle activity and force.
Main Results:
- Distinct scapular orientations were consistently achieved and statistically different.
- Scapular orientation and exertion direction significantly influenced muscle recruitment.
- Scapular orientation did not affect hand force capability, but exertion direction did.
Conclusions:
- Findings support neutral scapular orientations for injury risk reduction due to balanced muscle activation.
- Downward exertions may be preferable, potentially leading to lower muscle activity and higher maximal forces.
Related Concept Videos
01:23Muscles of the Shoulder
The muscles surrounding the shoulder girdle, including the clavicle and scapula, primarily stabilize the scapula. This stable base allows other muscles to move the humerus effectively. Scapular movements often mirror those of the humerus and extend its range of motion. For instance, raising the arm above the head would not be feasible without simultaneous upward rotation of the scapula.
Anterior Thoracic Muscles
The anterior thoracic muscles include the serratus anterior, subclavius, and...
Anterior Thoracic Muscles
The anterior thoracic muscles include the serratus anterior, subclavius, and...
01:31Muscles that Move the Arm
Nine muscles are involved in arm movements. Two of these, the pectoralis major and latissimus dorsi, originate from the axial skeleton and are called axial muscles. The other seven originate from the scapula and are called the scapular muscles.
The pectoralis major has two origins. Its clavicular head originates on the medial half of the clavicle. In contrast, the sternocostal head originates on the costal cartilages of ribs 1-6, the sternum, and the aponeurosis of the external oblique of the...
The pectoralis major has two origins. Its clavicular head originates on the medial half of the clavicle. In contrast, the sternocostal head originates on the costal cartilages of ribs 1-6, the sternum, and the aponeurosis of the external oblique of the...
01:19Bones of the Upper Limb: Humerus
The upper limb consists of the arm, forearm, wrist, and hand bones. The humerus is the single bone of the upper arm region. Proximally, it has a large, spherical, smooth head that articulates with the glenoid cavity of the scapula to form the glenohumeral or shoulder joint. The margin of the head is the anatomical neck, a residual epiphyseal plate. Laterally it extends to form bony projections called the greater tubercle and the lesser tubercle. Next to the tubercles is the surgical neck, a...