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Bill Stodart, Maria Cup, and Curtis Kindel

 al . Electromyographic activity of selected shoulder muscles in commonly used therapeutic exercises . Phys Ther . 1993 ; 73 : 668 – 677 . PubMed ID: 8378423 doi:10.1093/ptj/73.10.668 10.1093/ptj/73.10.668 8378423 14. Leggin BG , Neuman RM , Lannotti JP , Williams GR , Thompson EC . Intrarater and

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Renan Lima Monteiro, Joana Hoverter Facchini, Diego Galace de Freitas, Bianca Callegari, and Sílvia Maria Amado João

Context:

Pelvic-drop exercises are often used to strengthen the gluteus medius (GM) muscle with the aim of increasing or prioritizing its recruitment. However, the effect of hip rotation on the performance of the action of the GM is unknown.

Objective:

To evaluate the effect of hip rotation on the recruitment of the GM, tensor fasciae latae (TFL), and quadratus lumborum (QL).

Method:

Seventeen healthy subjects performed 2 sets of 4 repetitions of pelvic-drop exercise in random order with pelvic-drop lateral, medial, and neutral rotation of the hip.

Main Outcome Measures:

The electromyographic (EMG) activity of the GM, TFL, and QL was evaluated using surface electromyography.

Results:

There were significant increases in the activation of the GM with medial and neutral rotation compared with lateral rotation (P = .03, P = .01, respectively), and there was no difference between medial and neutral rotation (P = 1.00). There was no difference in EMG activity of the TFL and QL in any of the positions. The GM:TFL ratio was the same in all analyzed positions. Regarding the GM:QL ratio, there was a significant increase with medial rotation compared with lateral rotation (P = .02).

Conclusions:

Pelvic-drop exercises are more efficient for activating the GM when the hip is in medial rotation and neutral position.

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Gary E. Morin, David Tiberio, and Gary Austin

A characteristic of scapulothoracic dysfunction is the tendency for the upper regions of the trapezius to hypertrophy in relation to its middle and lower portions. This creates a muscular imbalance that can alter scapular position and subsequently the length–tension relationship of the shoulder muscles. Tape was applied over the right upper trapezius to inhibit electrical activity in the muscles of 10 uninjured subjects. EMG activity was recorded in two locations of the upper trapezius and one location in the middle to lower trapezius region while each subject maintained an isometric contraction designed to activate both muscles. With the tape applied, there was a statistically significant reduction in EMG activity of the upper trapezius with a corresponding increase in the middle/lower trapezius. The ability of the tape to alter trapezius activity in this fashion may help correct muscular imbalances in the trapezius muscle.

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Viire Talts, Jaan Ereline, Tatjana Kums, Mati Pääsuke, and Helena Gapeyeva

Our aim with the current study was to compare upper extremity and cue kinematics, and electromyographic (EMG) activation of shoulder muscles during novus (a special form of billiards) shots of different difficulty levels. Ten proficient and 10 less-skilled novus players performed 3 types of novus shots (penalties, cuts, rebounds) 10 times each. During each shot, elbow flexion and cue–forearm angles (using a movement analysis system), and surface EMG activity of the trapezius, posterior, and lateral deltoid muscles of each subject’s dominant side, were measured. Data were compared between more- and less-skilled players, and successful compared with unsuccessful shots. Elbow flexion angle among the more-skilled players was 24.5% larger (P < .001) during unsuccessful cut shots than successful ones. The more-skilled players performed successful penalty and rebound shots with 26.8% and 49.8% lower (P < .01 and P < .001, respectively) EMG activity of the trapezius muscle than unsuccessful ones. Less-skilled players’ shots were characterized by higher EMG activity in the trapezius muscle. The obtained findings suggest that the more-skilled novus players had acquired a different muscle recruitment pattern than less-skilled players.

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Ui-jae Hwang, Oh-yun Kwon, In-cheol Jeon, Si-hyun Kim, and Jong-hyuck Weon

Context:

The push-up-plus (PP) exercise has been recommended for strengthening of the serratus anterior (SA). Previous studies have investigated the effect of different stability properties of the base of support to adjust the difficulty level of SA muscle-strengthening exercises in the PP position. However, the optimal humeral-elevation angle (HEA) for selective activation and maximum contraction of the SA during PP has not been investigated.

Objectives:

To assess the effects of HEA during PP on electromyographic (EMG) activity in the SA, upper trapezius (UT), and pectoralis major (PM) and on the UT:SA and PM:SA activity ratios.

Design:

Comparative, repeated-measures design.

Setting:

University research laboratory.

Participants:

29 healthy men.

Main Outcome Measures:

The subjects performed PP at 3 different HEAs (60°, 90°, and 120°); EMG activity in the SA, UT, and PM was measured, and the UT:SA and PM:SA activity ratios were calculated. Differences in muscle activity and ratios between the 60°, 90°, and 120° HEAs were assessed using 1-way repeated-measures analysis of variance; the Bonferroni correction was applied.

Results:

SA muscle activity was significantly increased, in order of magnitude, at the 120°, 90°, and 60° HEAs. UT:SA and PM:SA activity ratios were significantly greater during performance of the PP at an HEA of 60° than at HEAs of 120° and 90°.

Conclusion:

The results suggest that an HEA of 120° should be used during performance of the PP because it produces greater SA activation than HEAs of 60° and 90°.

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Esther Suter, Walter Herzog, and Robert Bray

This study assessed muscle inhibition in patients with chronic anterior cruciate ligament (ACL) deficiency or ACL reconstruction. A series of protocols were tested for their effectiveness in increasing activity of the individual knee extensor muscles and decreasing muscle inhibition of the whole quadriceps group. Quadriceps muscle inhibition was measured by superimposing an electrical twitch onto the quadriceps muscle during a maximal voluntary knee extension. The level of activation of the individual knee extensor and knee flexor muscles was assessed via electromyography (EMG). Patients with ACL pathologies showed strength deficits and muscle inhibition in the knee extensors of the involved leg and the contralateral leg. Muscle inhibition was statistically significantly greater in ACL-deficient patients compared to ACL-reconstructed patients. When a knee extension was performed in combination with a hip extension, there was a significant increase, p < 0.05, in activation of the vastus medialis and vastus lateralis muscles compared to isolated knee extension. The use of an anti-shear device, designed to help stabilize the ACL-deficient knee, resulted in increased inhibition in the quadriceps muscle. Furthermore, a relatively more complete activation of the vasti compared to the rectus femoris was achieved during a fatiguing isometric contraction. Based on the results of this study, it is concluded that performing knee extension in combination with hip extension, or performing fatiguing knee extensor contractions, may be more effective in fully activating the vasti muscles than an isolated knee extensor contraction. Training interventions are needed to establish whether these exercise protocols are more effective than traditional rehabilitation approaches in decreasing muscle inhibition and achieving better functional recovery, including equal muscle strength in the injured and the contralateral leg.

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Bret Contreras, Andrew D. Vigotsky, Brad J. Schoenfeld, Chris Beardsley, and John Cronin

The back squat and barbell hip thrust are both popular exercises used to target the lower body musculature; however, these exercises have yet to be compared. Therefore, the purpose of this study was to compare the surface electromyographic (EMG) activity of the upper and lower gluteus maximus, biceps femoris, and vastus lateralis between the back squat and barbell hip thrust. Thirteen trained women (n = 13; age = 28.9 years; height = 164 cm; mass = 58.2 kg) performed estimated 10-repetition maximums (RM) in the back squat and barbell hip thrust. The barbell hip thrust elicited significantly greater mean (69.5% vs 29.4%) and peak (172% vs 84.9%) upper gluteus maximus, mean (86.8% vs 45.4%) and peak (216% vs 130%) lower gluteus maximus, and mean (40.8% vs 14.9%) and peak (86.9% vs 37.5%) biceps femoris EMG activity than the back squat. There were no significant differences in mean (99.5% vs 110%) or peak (216% vs 244%) vastus lateralis EMG activity. The barbell hip thrust activates the gluteus maximus and biceps femoris to a greater degree than the back squat when using estimated 10RM loads. Longitudinal training studies are needed to determine if this enhanced activation correlates with increased strength, hypertrophy, and performance.

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Jayshree Shah, Tarushi Tanwar, Iram Iram, Mosab Aldabbas, and Zubia Veqar

hypothesis, that an increased lumbar lordosis will alter SEMG activity (percentage of MVC of MF, LT, and MF–LT activity ratio) during quadruped stabilization exercise. A surge of 9.7% and 16.9% MVC of MF electromyographic activity with increased lumbar lordosis posture as compared with a neutral posture in

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Karinna Sonálya Aires da Costa, Daniel Tezoni Borges, Liane de Brito Macedo, Caio Alano de Almeida Lins, and Jamilson Simões Brasileiro

improve neuromuscular performance, balance, and bone mineral density in different populations. 7 – 9 Some studies have shown that the use of a vibrating platform can increase amplitude of electromyographic activity, muscle strength, and average power and can improve postural balance. 10 – 12 Literature

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Kunal Bhanot, Navpreet Kaur, Lori Thein Brody, Jennifer Bridges, David C. Berry, and Joshua J. Ode

PG , Rodgers MM , Romani WA . Muscles: Testing and Function, With Posture and Pain . 5th ed. Baltimore, MD : Lippincott Williams & Wilkins ; 2005 . 30. Souza GM , Baker LL , Powers CM . Electromyographic activity of selected trunk muscles during dynamic spine stabilization