Effect of continuous, mechanically passive, anti-gravity assistance on kinematics and muscle activity during dynamic 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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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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The effect of head position on scapular orientation and muscle activity during shoulder elevation

Journal of Occupational Rehabilitation ◽

10.1007/bf02110752 ◽

1996 ◽

Vol 6 (3) ◽

pp. 147-158 ◽

Cited By ~ 30

Author(s):

Paula M. Ludewig ◽

Thomas M. Cook

Keyword(s):

Muscle Activity ◽

Head Position ◽

Shoulder Elevation

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Comparison of Muscle Activity Ratio of Upper Trapezius to Serratus Anterior During Shoulder Elevation Between Subjects With and Without Pain Experienced in Upper Trapezius

Physical Therapy Korea ◽

10.12674/ptk.2014.21.2.067 ◽

2014 ◽

Vol 21 (2) ◽

pp. 67-73 ◽

Cited By ~ 2

Author(s):

Sun-Hee Ahn ◽

Oh-Yun Kwon ◽

Sung-Dae Choung ◽

Si-Hyun Kim ◽

In-Cheol Jeon

Keyword(s):

Muscle Activity ◽

Activity Ratio ◽

Serratus Anterior ◽

Upper Trapezius ◽

Shoulder Elevation

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Myoelectric Activity Differences in Three Learning Sessions

Journal of Psychophysiology ◽

10.1027//0269-8803.16.2.92 ◽

2002 ◽

Vol 16 (2) ◽

pp. 92-96

Author(s):

Tiina Ritvanen ◽

Reijo Koskelo ◽

Osmo H„nninen

Keyword(s):

High School Students ◽

Muscle Activity ◽

Muscle Tension ◽

Emg Activity ◽

Traditional Learning ◽

Myoelectric Activity ◽

School Students ◽

Language Laboratory ◽

Upper Trapezius ◽

Muscle Groups

Abstract This study follows muscle activity in three different learning sessions (computer, language laboratory, and normal classroom) while students were studying foreign languages. Myoelectric activity was measured in 21 high school students (10 girls, 11 boys, age range 17-20 years) by surface electromyography (sEMG) from the upper trapezius and frontalis muscles during three 45-min sessions. Root mean square (RMS) average from both investigated muscles was calculated. The EMG activity was highest in both muscle groups in the computer-aided session and lowest in the language laboratory. The girls had higher EMG activity in both investigated muscle groups in all three learning situations. The measured blood pressure was highest at the beginning of the sessions, decreased within 10 min, but increased again toward the end of the sessions. Our results indicate that the use of a computer as a teaching-aid evokes more constant muscle activity than the traditional learning situations. Since muscle tension can have adverse health consequences, more research is needed to determine optimal classroom conditions, especially when technical aids are used in teaching.

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