Arm posture influences on regional supraspinatus and infraspinatus activation in isometric arm elevation efforts

Alenabi, Talia; Whittaker, Rachel L.; Kim, Soo Y.

doi:10.1016/j.jelekin.2018.12.005

Cited by 20 publications

(17 citation statements)

References 28 publications

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“…he modulation of infraspinatus (IS) muscle activity has been identified in a variety of intervention exercises for injury prevention. [1][2][3]9,24,28 However, professional tennis players present with IS atrophy syndrome to which the cause is uncertain. 31 Another shoulder external rotator muscle, the teres minor (TMi) muscle, generates up to 45% of external rotation (ER) force compared with the IS muscle.…”

mentioning

confidence: 99%

The Application of Double Elastic Band Exercise in the 90/90 Arm Position for Overhead Athletes

Tsuruike

Ellenbecker²,

Lauffenburger

2020

Sports Health

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Background: Traditional exercises performed with the shoulder in the position of 90° abduction and external rotation with elbow flexion (90/90) while using a single elastic band showed moderate activity of both the lower trapezius (LT) and infraspinatus (IS) muscle. The purpose of this study was to investigate activity of the teres minor (TMi) and the LT muscles during standing external rotation exercise with the shoulder in the 90/90 position with 2 elastic bands in both the frontal and the scapular plane. Hypothesis: TMi, IS, and LT muscle activities will vary depending on whether the shoulder is positioned in the frontal or scapular plane with the application of 2 elastic bands. Also, the serratus anterior (SA) and teres major (TMa) muscles will produce different muscular activity patterns during exercises performed with 2 elastic bands in the frontal plane compared with the TMi and LT muscles. Study Design: Controlled laboratory study Level of Evidence: Level 4. Methods: A total of 21 collegiate baseball players volunteered to participate. The electromyography (EMG) activities of the TMi, IS, LT, SA, TMa, middle deltoid (MD), posterior deltoid, and upper trapezius (UT) muscles were measured with the 90/90 arm position during both isometric and oscillation resistance exercises with 2 elastic bands oriented in the frontal and scapular planes. Results: A significant difference was observed in EMG activity of both the TMi and the LT muscles between single and double elastic band applications in the frontal plane ( P < 0.05). In contrast, EMG activity of the IS, SA, and TMa muscles was significantly increased in the scapular plane compared with the frontal plane ( P < 0.05). Conclusion: The standing 90/90 position effectively increased both TMi and LT muscle EMG activity with the double elastic band in the frontal plane while minimizing UT and MD muscle activity. EMG activity of the IS, SA, and TMa muscles increased with exercise in the scapular plane as compared with the frontal plane. Clinical Relevance: Oscillation movement under double elastic band application differentiated external rotator muscle and scapular muscle activities between the frontal and scapular plane during the 90/90 exercise in the frontal plane compared with the scapular plane. Clinicians can utilize each of the scapular and frontal positions based on their desired focus for muscular activation.

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mentioning

confidence: 99%

The Application of Double Elastic Band Exercise in the 90/90 Arm Position for Overhead Athletes

Tsuruike

Ellenbecker²,

Lauffenburger

2020

Sports Health

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“…These results coincide with the activity values in the middle partition observed in our study. Some investigators measured independent activation of those partitions using EMG, and concluded that the muscle partitions have different roles [ 1 , 2 , 4 , 14 ]. However, EMG measurements from the partitions were not obtained during scaption, rather during specific positions, e.g.…”

Section: Discussionmentioning

confidence: 99%

“…empty can test. On the other hand, Alenabi et al 2019 [ 2 ] measured EMG in the superior and middle partitions of the ISP muscle at 30°, 90°, and 150° during scaption and demonstrated that the activation of both the superior and middle partitions of the ISP muscle, with 50% maximal voluntarily contraction, increased with increasing angle. These results are not in line with those obtained in the current study for the middle partition.…”

Section: Discussionmentioning

confidence: 99%

“…While some investigators tried to measure independent activations of the partitions of the ISP muscle using EMG, it is difficult to measure the activation of each partition, especially in the inferior partition, throughout various shoulder motions as the fine wires can be displaced out of the muscle during contraction [ 1 , 2 , 4 , 14 ]. Shear-wave ultrasound elastography (SWE) has been previously implemented to measure shear modulus of muscles, as a surrogate for muscle stiffness.…”

Section: Introductionmentioning

confidence: 99%

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Shoulder scaption is dependent on the behavior of the different partitions of the infraspinatus muscle

et al. 2021

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Purpose The purpose of this study was to investigate if the three partitions (superior, middle, and inferior partitions) of the infraspinatus muscle previously described in anatomical studies will present different behavior during scapular plane abduction (scaption) as described using shear-wave elastography, especially during initial range of motion. Methods Eight volunteers held their arm against gravity 15° intervals from 30° to 150° in scaption. Shear-wave elastography was implemented at each position to measure shear modulus at rest and during muscle contraction, as a surrogate for muscle stiffness, of each partition. Muscle activity was defined as the difference in stiffness values between the resting positions and those during muscle contraction (ΔE = stiffness at contraction—stiffness at rest). Results The activity value for the middle partition was 25.1 ± 10.8 kPa at 30° and increased up to 105° (52.2 ± 10.8 kPa), with a subsequent decrease at larger angle positions (p < .001). The superior partition showed a flatter and constant behavior with smaller activity values except at higher angles (p < .001). Peak activity values for the superior partition were observed at 135° (23.0 ± 12.0 kPa). Increase activity for inferior partition began at 60° and showed a peak at 135° (p < .001; 32.9 ± 13.8 kPa). Conclusion Stiffness measured using shear-wave elastography in each partition of the infraspinatus muscle demonstrated different behavior between these partitions during scaption. The middle partition generated force throughout scaption, while the superior and inferior partitions exerted force at end range.

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“…Kim et al subdivided the anterior and the posterior regions into superficial, middle and deep sub-regions each based on fiber bundle arrangement (8). EMG studies have evaluated the functions of the morphologically divided regions (11,12). EMG data were obtained from the anterior and posterior regions suggesting that the anterior region was a mover and the posterior region acted as stress control for the anterior region (11,12).…”

Section: Introductionmentioning

confidence: 99%

Coordination of the Sub-Regions of the Supraspinatus and Deltoid Muscles During Shoulder Scaption: a Shear Wave Elastography Study

Hoshikawa¹,

Yuri²,

Mura³

et al. 2021

Muscle Ligaments and Tendons J

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Background. Understanding the functional role of the supraspinatus (SSP) and deltoid muscles during shoulder motion is a basis for understanding rotator cuff pathology and for the development of appropriate rehabilitation protocols. The purpose of this study was to elucidate the coordination, focusing on activation timing, of the sub-regions of the SSP muscle and of the middle region of deltoid muscle during scapular plane abduction (scaption) using shear wave elastography (SWE). Methods. Twelve healthy male volunteers without any restrictions in their shoulder joints, altered posture or scapulothoracic dyskinesis were recruited to this study. Participants were instructed to sit on a chair with their back against the back-rest. Measurements of the non-dominant arm were obtained at rest and during isometric contraction at a neutral position and every 15° interval from 30° to 150° during scaption. Muscle activity was defined as the difference in SWE-measured stiffness between resting outcomes and those measured during muscle contraction (∆E = stiffness during contraction -stiffness at rest). Results. The anterior-middle sub-region of the SSP muscle and the middle region of the deltoid muscle presented a mountain-shape type curve with peaks at 60° (146.2 ± 26.6 kPa) and at 90° (142.0 ± 25.9 kPa), respectively. The anterior-superficial sub-region of SSP muscle peaked at 30° (102.1 ± 27.4 kPa), linearly decreasing thereafter. Conclusions. The anterior-superficial sub-region of the SSP muscle showed activity during initial range of motion, while the anterior-middle sub-region showed activity at early mid-range. On the contrary, the middle region of the deltoid muscle showed increased SWE-measured activity at late mid-range. A more refined approach focusing on the muscles sub-regions may lead to improved rehabilitation protocols.

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Arm posture influences on regional supraspinatus and infraspinatus activation in isometric arm elevation efforts

Cited by 20 publications

References 28 publications

The Application of Double Elastic Band Exercise in the 90/90 Arm Position for Overhead Athletes

The Application of Double Elastic Band Exercise in the 90/90 Arm Position for Overhead Athletes

Shoulder scaption is dependent on the behavior of the different partitions of the infraspinatus muscle

Coordination of the Sub-Regions of the Supraspinatus and Deltoid Muscles During Shoulder Scaption: a Shear Wave Elastography Study

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