The effect of head position on scapular orientation and muscle activity during shoulder elevation

Abstract BackgroundMechanically passive (i.e. spring-powered) exoskeletons may be a practical and affordable solution to meet a growing clinical need for continuous, home-based movement assistance. We designed, fabricated, and preliminarily evaluated the performance of a wearable, passive, cam-driven shoulder exoskeleton (WPCSE) prototype. MethodsThe novel feature of the WPCSE is a modular spring-cam-wheel module, which generates an assistive force that can be customized to compensate for any proportion of the shoulder elevation moment due to gravity. We performed a benchtop experiment to validate the mechanical output of the WPCSE against our theoretical model. We also conducted a pilot biomechanics study (four able-bodied subjects) to quantify the effect of a WPCSE prototype on muscle activity and shoulder kinematics during three one-degree-of-freedom shoulder movements. ResultsThe shoulder elevation moment produced by the spring-cam-wheel module alone closely matched the desired, theoretical moment. However, when measured from the full WPCSE prototype, the moment was lower (up to 30%) during positive shoulder elevation and higher (up to 120%) during negative shoulder elevation compared to the theoretical moment, due primarily to friction. Even so, a WPCSE prototype, compensating for about 25% of the shoulder elevation moment due to gravity, showed a trend of reducing root mean square (up to 50%) and peak (up to 53%) electromyogram magnitudes of several muscles crossing the shoulder during shoulder elevation and horizontal adduction/abduction movements. Subjects verbally reported that the WPCSE did not physically constrain them during the tested movements. ConclusionThe results provide proof-of-concept evidence that our WPCSE can potentially assist shoulder movements. The proposed WPCSE, once refined, could provide clinical and home-based rehabilitation for patients with shoulder disability.

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Changes in upper airway muscle activity related to head position in awake cats

Respiration Physiology ◽

10.1016/0034-5687(85)90102-1 ◽

1985 ◽

Vol 60 (2) ◽

pp. 181-192 ◽

Cited By ~ 29

Author(s):

Monique Bonora ◽

Donald Bartlett ◽

Susan L. Knuth

Keyword(s):

Muscle Activity ◽

Upper Airway ◽

Head Position ◽

Awake Cats

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Effect of halo-type frontal cockpit protection on overtaking

BMJ Case Reports ◽

10.1136/bcr-2018-225427 ◽

2018 ◽

pp. bcr-2018-225427 ◽

Cited By ~ 2

Author(s):

Simon M Rosalie ◽

James M Malone

Keyword(s):

Cervical Spine ◽

Muscle Activity ◽

Visual Cues ◽

National Level ◽

Compressive Loading ◽

Head Position ◽

Type Structure ◽

Erector Spinae ◽

Neck Muscle ◽

Central Pillar

In 2018, the Fédération Internationale de l’Automobile introduced the halo frontal cockpit protection system into Formula 1. While extensive testing was conducted to confirm that the halo protects the driver from contact, the halo’s effect on the driver during overtaking was not tested prior to its introduction. Here, we describe the effect of a halo-type structure on the neck muscle activity of one of the authors, a national-level amateur racing driver, during on-track simulations designed to practise overtaking. We found that the halo-type structure caused an increase in the rates of fatigue and workloads of sternocleidomastoid and cervical erector spinae. The results suggest that the driver adopted a forward and right laterally flexed head position, presumably to clear the central pillar from his visible field. This has the potential to increase compressive loading of the cervical spine and affect the ability to use visual cues during steering manoeuvres.

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Electromyographic Study of Neck Muscle Activity According to Head Position in Rugby Tackles

Journal of Physical Therapy Science ◽

10.1589/jpts.25.563 ◽

2013 ◽

Vol 25 (5) ◽

pp. 563-566 ◽

Cited By ~ 5

Author(s):

Koji Morimoto ◽

Masaaki Sakamoto ◽

Takashi Fukuhara ◽

Kazuo Kato

Keyword(s):

Muscle Activity ◽

Head Position ◽

Neck Muscle

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Comparing trapezius muscle activity in the different planes of shoulder elevation

Journal of Physical Therapy Science ◽

10.1589/jpts.27.1495 ◽

2015 ◽

Vol 27 (5) ◽

pp. 1495-1497 ◽

Cited By ~ 3

Author(s):

Tomonobu Ishigaki ◽

Tomoya Ishida ◽

Mina Samukawa ◽

Hiroshi Saito ◽

Motoki Hirokawa ◽

...

Keyword(s):

Muscle Activity ◽

Trapezius Muscle ◽

Shoulder Elevation

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Incorporation of the Kinetic Chain Into Shoulder-Elevation Exercises: Does It Affect Scapular Muscle Activity?

Journal of Athletic Training ◽

10.4085/1062-6050-136-19 ◽

2020 ◽

Vol 55 (4) ◽

pp. 343-349

Author(s):

Dorien Borms ◽

Annelies Maenhout ◽

Ann M Cools

Keyword(s):

Lower Limb ◽

Muscle Activity ◽

Mean Difference ◽

Hand Position ◽

Electromyographic Activity ◽

Kinetic Chain ◽

Serratus Anterior ◽

Single Plane ◽

Rehabilitation Exercises ◽

Shoulder Elevation

Context Scapular rehabilitation exercises should focus on selective activation of weaker muscles and minimal activation of hyperactive muscles. For rehabilitation of overhead athletes, single-plane open chain exercises below 90° of shoulder elevation are often recommended. Moreover, incorporating the kinetic chain in shoulder rehabilitation exercises is advised and has been suggested to influence scapular muscle activity levels. Objective To study the influence of kinetic chain incorporation during 5 variations of a shoulder-elevation exercise on scapular muscle activity. Design Cross-sectional study. Setting University laboratory. Patients or Other Participants Thirty-one asymptomatic participants (15 men, 16 women). Main Outcome Measure(s) The electromyographic activity of the upper (UT), middle (MT), and lower (LT) trapezius, and serratus anterior was determined during 5 variations of bilateral elevation with external rotation: (1) open-hand position (reference exercise), (2) closed-hand position, (3) dynamic bipedal squat, (4) static unipedal squat, and (5) dynamic unipedal squat on the contralateral leg. All data were normalized as a percentage of maximal voluntary isometric contraction (MVIC). Results A closed-hand position (exercise 2) instead of an open-hand position (exercise 1) resulted in lower MT (mean difference = 3.44% MVIC) and LT (mean difference = 7.76% MVIC) activity. Incorporating the lower limb (exercises 3–5) increased UT activity when compared with exercise 1 (mean differences = 3.67, 2.68, 5.02% MVIC, respectively), which in general resulted in increased UT : MT ratios. Additionally, LT activity decreased when a dynamic unipedal squat was added (mean difference: 4.90% MVIC). For the serratus anterior, the greatest activity occurred during elevation in a static unipedal squat position (exercise 4, 22.90% MVIC). Conclusions Incorporating the kinetic chain during shoulder-elevation exercises influenced scapular muscle activity and ratios. In particular, incorporating the lower limb resulted in more UT activity, whereas the open-hand position increased MT and LT activity.

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Relevance of Arm Position and Muscle Activity on Three-Dimensional Glenohumeral Translation in Patients with Traumatic and Atraumatic Shoulder Instability

The American Journal of Sports Medicine ◽

10.1177/03635465020300041101 ◽

2002 ◽

Vol 30 (4) ◽

pp. 514-522 ◽

Cited By ~ 55

Author(s):

Ruediger M. O. von Eisenhart-Rothe ◽

Alwin Jäger ◽

Karl-Hans Englmeier ◽

Thomas J. Vogl ◽

Heiko Graichen

Keyword(s):

Shoulder Instability ◽

Muscle Activity ◽

Clinical Relevance ◽

External Rotation ◽

Three Dimensional ◽

Contralateral Side ◽

Therapeutic Strategies ◽

Head Position ◽

Resonance Imaging ◽

Open Magnetic Resonance Imaging

Background No quantitative data on glenohumeral translation exist allowing one to distinguish insufficiency of the active or passive stabilizers in different forms of shoulder instability. Hypothesis To determine whether 1) in traumatic or atraumatic shoulder instability an increase of glenohumeral translation can be observed in specific relevant arm positions, 2) muscle activity leads to recentering of the humeral head, and 3) there exist differences between traumatic and atraumatic instability. Study Design Prospective clinical trial. Methods In 12 patients with traumatic and 10 patients with atraumatic instability, both shoulders were examined in different arm positions—with and without muscle activity—by using open magnetic resonance imaging and a three-dimensional postprocessing technique. Results At 90° of abduction and external rotation, translation (anterior-inferior) was significantly higher in patients with traumatic unstable shoulders compared with their contralateral side (3.6 ± 1.5 versus 0.7 ± 1.6 mm). In patients with atraumatic instability, significantly increased translation (4.7 ± 2.0 mm) was observed, with the direction being nonuniform. Muscle activity led to significant recentering in traumatic but not in atraumatic instability. Conclusions In traumatic instability, increased translation was observed only in functionally important arm positions, whereas intact active stabilizers demonstrate sufficient recentering. In atraumatic instability, a decentralized head position was recorded also during muscle activity, suggesting alterations of the active stabilizers. Clinical Relevance Clinical Relevance: These data are relevant for optimizing diagnostics and therapeutic strategies.

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