Thoracic posture, shoulder muscle activation patterns and isokinetic strength of semi-professional rugby union players

Background. Shoulder injuries are the most severe injuries in rugby union players, accounting for almost 20% of injuries related to the sport and resulting in lost playing hours.Objective. To profile the thoracic posture, scapular muscle activation patterns and rotator cuff muscle isokinetic strength of semi-professionalrugby union players.Methods. Using the hand-behind-the-neck and -back methods, we manually tested the range of motion (ROM) of the shoulder joints of 91 uninjured semi-professional rugby union players who consented to participate in the study. Profiling and classification of thoracic posture was performed according to the New York Posture Test. Activation patterns of the upper and lower trapezius, serratus anterior and infraspinatus scapular muscles were determined by electromyography. The isokinetic muscle strength of the rotator cuff muscles was determined at 60°/sec by measuring the concentric and eccentric forces during internal rotation (IR) and external rotation (ER).Results. Participants presented with non-ideal or unsatisfactory internal (59%) and external (85%) rotators of the shoulder. A slightly abnormal or abnormal forward head posture was observed in 55% of participants, while 68% had an abnormal shoulder position in the lateral view. The muscle activation sequence of the rotator cuff muscles was: (i) serratus anterior, (ii) lower trapezius, (iii) infraspinatus, and (iv) upper trapezius. The isokinetic ER/IR muscle-strength ratio during concentric muscle contraction was 64% (standard deviation (SD) ±14) for the left shoulder and 54% (SD ±10) for the right shoulder. The ER/IR ratio for eccentric muscle contraction was 67% (SD ±12) and 61% (SD ±9) for the left and right shoulders, respectively.Conclusions. Non-ideal or unsatisfactory flexibility of the external rotators of the shoulder, a forward shoulder posture in the lateral view, and weakness of the external rotators did not result in an abnormal rotator cuff muscle activation pattern in this study. Postural deviations may, however, increase the risk of shoulder injury in rugby union players in the long term, and should be corrected.

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Thoracic posture, shoulder muscle activation patterns and isokinetic strength of semi-professional rugby union players

South African Journal of Sports Medicine ◽

10.7196/sajsm.366 ◽

2013 ◽

Vol 25 (1) ◽

Author(s):

Sarah J Moss ◽

Garth Bolton ◽

Martinique Sparks ◽

Pierre C Venter

Keyword(s):

Muscle Activation ◽

Rugby Union ◽

Isokinetic Strength ◽

Activation Patterns ◽

Muscle Activation Patterns ◽

Shoulder Muscle

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Aging Related Changes in the Kinematics of Walking: A Potential Pathway to Changes in Cartilage Morphology

ASME 2012 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2012-80677 ◽

2012 ◽

Author(s):

K. A. Boyer ◽

T. P. Andriacchi

Keyword(s):

Muscle Strength ◽

Knee Osteoarthritis ◽

Muscle Activation ◽

Sagittal Plane ◽

Activation Patterns ◽

Muscle Activation Patterns ◽

Age Related ◽

Ligament Stiffness ◽

Spatio Temporal ◽

Age Related Changes

Age-related changes in spatio-temporal and sagittal plane walking mechanics are well documented [1, 2]. These changes along with age-related changes in muscle strength, muscle activation patterns and ligament stiffness [3] may also lead to changes in both rotational and translation motions at the knee. It has been suggested that alterations in the normal kinematics of the knee related to aging may be a contributing factor to the increased incidence of knee osteoarthritis (OA) with aging [4].

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Assessing the validity of surface electromyography for recording muscle activation patterns from serratus anterior

Journal of Electromyography and Kinesiology ◽

10.1016/j.jelekin.2014.01.007 ◽

2014 ◽

Vol 24 (2) ◽

pp. 221-227 ◽

Cited By ~ 21

Author(s):

Lucien Hackett ◽

Darren Reed ◽

Mark Halaki ◽

Karen A. Ginn

Keyword(s):

Surface Electromyography ◽

Muscle Activation ◽

Serratus Anterior ◽

Activation Patterns ◽

Muscle Activation Patterns

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Pathological muscle activation patterns in patients with massive rotator cuff tears, with and without subacromial anaesthetics

Manual Therapy ◽

10.1016/j.math.2006.07.004 ◽

2006 ◽

Vol 11 (3) ◽

pp. 231-237 ◽

Cited By ~ 61

Author(s):

F. Steenbrink ◽

J.H. de Groot ◽

H.E.J. Veeger ◽

C.G.M. Meskers ◽

M.A.J. van de Sande ◽

...

Keyword(s):

Rotator Cuff ◽

Muscle Activation ◽

Rotator Cuff Tears ◽

Activation Patterns ◽

Massive Rotator Cuff Tears ◽

Muscle Activation Patterns

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Scapular Bracing and Alteration of Posture and Muscle Activity in Overhead Athletes With Poor Posture

Journal of Athletic Training ◽

10.4085/1062-6050-48.1.13 ◽

2013 ◽

Vol 48 (1) ◽

pp. 12-24 ◽

Cited By ~ 28

Author(s):

Ashley K. Cole ◽

Melanie L. McGrath ◽

Shana E. Harrington ◽

Darin A. Padua ◽

Terri J. Rucinski ◽

...

Keyword(s):

Muscle Activity ◽

Muscle Activation ◽

Surface Emg ◽

Lateral View ◽

Controlled Clinical Trial ◽

Serratus Anterior ◽

Overhead Athletes ◽

Forward Flexion ◽

Upper Trapezius ◽

Lower Trapezius

Context: Overhead athletes commonly have poor posture. Commercial braces are used to improve posture and function, but few researchers have examined the effects of shoulder or scapular bracing on posture and scapular muscle activity. Objective: To examine whether a scapular stabilization brace acutely alters posture and scapular muscle activity in healthy overhead athletes with forward-head, rounded-shoulder posture (FHRSP). Design: Randomized controlled clinical trial. Setting: Applied biomechanics laboratory. Patients or Other Participants: Thirty-eight healthy overhead athletes with FHRSP. Intervention(s): Participants were assigned randomly to 2 groups: compression shirt with no strap tension (S) and compression shirt with the straps fully tensioned (S + T). Posture was measured using lateral-view photography with retroreflective markers. Electromyography (EMG) of the upper trapezius (UT), middle trapezius (MT), lower trapezius (LT), and serratus anterior (SA) in the dominant upper extremity was measured during 4 exercises (scapular punches, W's, Y's, T's) and 2 glenohumeral motions (forward flexion, shoulder extension). Posture and exercise EMG measurements were taken with and without the brace applied. Main Outcome Measure(s): Head and shoulder angles were measured from lateral-view digital photographs. Normalized surface EMG was used to assess mean muscle activation of the UT, MT, LT, and SA. Results: Application of the brace decreased forward shoulder angle in the S + T condition. Brace application also caused a small increase in LT EMG during forward flexion and Y's and a small decrease in UT and MT EMG during shoulder extension. Brace application in the S + T group decreased UT EMG during W's, whereas UT EMG increased during W's in the S group. Conclusions: Application of the scapular brace improved shoulder posture and scapular muscle activity, but EMG changes were highly variable. Use of a scapular brace might improve shoulder posture and muscle activity in overhead athletes with poor posture.

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Is the Occurrence of the Sticking Region in Maximum Smith Machine Squats the Result of Diminishing Potentiation and Co-Contraction of the Prime Movers among Recreationally Resistance Trained Males?

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18031366 ◽

2021 ◽

Vol 18 (3) ◽

pp. 1366

Author(s):

Roland van den Tillaar ◽

Eirik Lindset Kristiansen ◽

Stian Larsen

Keyword(s):

Muscle Activity ◽

Muscle Activation ◽

Gluteus Maximus ◽

Knee Extensors ◽

Force Output ◽

Activation Patterns ◽

Muscle Activation Patterns ◽

Prime Movers ◽

Almost All ◽

Height Data

This study compared the kinetics, barbell, and joint kinematics and muscle activation patterns between a one-repetition maximum (1-RM) Smith machine squat and isometric squats performed at 10 different heights from the lowest barbell height. The aim was to investigate if force output is lowest in the sticking region, indicating that this is a poor biomechanical region. Twelve resistance trained males (age: 22 ± 5 years, mass: 83.5 ± 39 kg, height: 1.81 ± 0.20 m) were tested. A repeated two-way analysis of variance showed that Force output decreased in the sticking region for the 1-RM trial, while for the isometric trials, force output was lowest between 0–15 cm from the lowest barbell height, data that support the sticking region is a poor biomechanical region. Almost all muscles showed higher activity at 1-RM compared with isometric attempts (p < 0.05). The quadriceps activity decreased, and the gluteus maximus and shank muscle activity increased with increasing height (p ≤ 0.024). Moreover, the vastus muscles decreased only for the 1-RM trial while remaining stable at the same positions in the isometric trials (p = 0.04), indicating that potentiation occurs. Our findings suggest that a co-contraction between the hip and knee extensors, together with potentiation from the vastus muscles during ascent, creates a poor biomechanical region for force output, and thereby the sticking region among recreationally resistance trained males during 1-RM Smith machine squats.

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Electromyographic activation patterns during swallowing in older adults

Scientific Reports ◽

10.1038/s41598-021-84972-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jin Young Ko ◽

Hayoung Kim ◽

Joonyoung Jang ◽

Jun Chang Lee ◽

Ju Seok Ryu

Keyword(s):

Older Adults ◽

Viscous Fluid ◽

Muscle Activation ◽

Fatty Infiltration ◽

Liquid Volume ◽

Type I ◽

Type Ii ◽

Activation Patterns ◽

Muscle Activation Patterns ◽

Age Related

AbstractAge-related weakness due to atrophy and fatty infiltration in oropharyngeal muscles may be related to dysphagia in older adults. However, little is known about changes in the oropharyngeal muscle activation pattern in older adults. This was a prospective and experimental study. Forty healthy participants (20 older [> 60 years] and 20 young [< 60 years] adults) were enrolled. Six channel surface electrodes were placed over the bilateral suprahyoid (SH), bilateral retrohyoid (RH), thyrohyoid (TH), and sternothyroid (StH) muscles. Electromyography signals were then recorded twice for each patient during swallowing of 2 cc of water, 5 cc of water, and 5 cc of a highly viscous fluid. Latency, duration, and peak amplitude were measured. The activation patterns were the same, in the order of SH, TH, and StH, in both groups. The muscle activation patterns were classified as type I and II; the type I pattern was characterized by a monophasic shape, and the type II comprised a pre-reflex phase and a main phase. The oropharyngeal muscles and SH muscles were found to develop a pre-reflex phase specifically with increasing volume and viscosity of the swallowed fluid. Type I showed a different response to the highly viscous fluid in the older group compared to that in the younger group. However, type II showed concordant changes in the groups. Therefore, healthy older people were found to compensate for swallowing with a pre-reflex phase of muscle activation in response to increased liquid volume and viscosity, to adjust for age-related muscle weakness.

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