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Josu Gomez-Ezeiza, Jordan Santos-Concejero, Jon Torres-Unda, Brian Hanley and Nicholas Tam

electromyography, were found to be higher in race walking than in running. 15 However, the key factor that might facilitate a more efficient oxygen cost of transport is the timing of muscle activation during the gait cycle, 16 as preactivation of lower limb posterior musculature has been found to relate to the

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Denver M.Y. Brown and Steven R. Bray

). In the exercise domain, studies have measured muscle activation (i.e., motor unit activation) while performing isometric muscle contractions ( Bray et al., 2008 ; Graham, Sonne, & Bray, 2014 ) and endurance cycling ( Pageaux, Marcora, Rozand, & Lepers, 2015 ). These studies have shown that

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Jeff A. Nessler, Thomas Hastings, Kevin Greer and Sean C. Newcomer

the bladder as needed while paddling in the ocean for extended periods of time. If the bladder can assist the surfer in maintaining the proper prone posture while paddling through passive extension of the trunk, this may result in less muscle activation of back, neck, and shoulder extensor muscles

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Graeme G. Sorbie, Fergal M. Grace, Yaodong Gu, Julien S. Baker and Ukadike C. Ugbolue

attention on predicting muscle activation levels in order to reduce injury risks and increase performance in the sport. 6 , 14 , 15 Golf-related EMG studies that have investigated the trunk muscles often include the erector spinae muscle. 8 , 13 , 16 These studies, however, have only investigated the

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Kristi Edgar, Aimee Appel, Nicholas Clay, Adam Engelsgjerd, Lauren Hill, Eric Leeseberg, Allison Lyle and Erika Nelson-Wong

-tolerant). These differences can be identified during standing a priori to LBP onset and include muscle activation patterns. 5 – 7 , 11 Individuals classified as standing-intolerant demonstrated a reversal of the typical muscle activation sequence during return-to-stand from forward flexion and atypical flexion

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Chad Van Ramshorst and Woochol Joseph Choi

  1 ). In each trial, vertical contact forces (ground reaction forces) were recorded through a force plate (NC-4060; Bertec). Muscle activation of the rectus femoris and gluteus medius muscles was also acquired by a wireless electromyography (EMG) system (EMG DTS system; Noraxon, Scottsdale, AZ

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S. Jayne Garland, Vicki L. Gray and Svetlana Knorr

Many stroke survivors have residual sensorimotor deficits that impact negatively on balance and quality of life. The purpose of this review is to provide an overview of the impairments in motor control following stroke and the impact of those impairments on muscle activation patterns during postural control in stroke. Motor control impairments following stroke result in force production that is slow, weak and lacking in precision making it difficult to produce a fast rate of force development with sufficient magnitude to be effective for postural responses. Whether postural perturbations require feedback or feedforward responses, there is impairment to the timing, magnitude and sequencing of muscle activation following stroke. The impairment in muscle activation is dependent on the extent of the motor control impairments and strategies used by the individuals following stroke to compensate for the impairments. The central nervous system uses a variety of mechanisms to improve the muscle activation patterns needed for the recovery of postural responses following stroke.

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Cameron Mitchell, Rotem Cohen, Raffy Dotan, David Gabriel, Panagiota Klentrou and Bareket Falk

Previous studies in adults have demonstrated power athletes as having greater muscle force and muscle activation than nonathletes. Findings on endurance athletes are scarce and inconsistent. No comparable data on child athletes exist.

Purpose:

This study compared peak torque (Tq), peak rate of torque development (RTD), and rate of muscle activation (EMG rise, Q30), in isometric knee extension (KE) and fexion (KF), in pre- and early-pubertal power- and endurance-trained boys vs minimally active nonathletes.

Methods:

Nine gymnasts, 12 swimmers, and 18 nonathletes (7–12 y), performed fast, maximal isometric KE and KF. Values for Tq, RTD, electromechanical delay (EMD), and Q30 were calculated from averaged torque and surface EMG traces.

Results:

No group differences were observed in Tq, normalized for muscle cross-sectional area. The Tq-normalized KE RTD was highest in power athletes (6.2 ± 1.9, 4.7 ± 1.2, 5.0 ± 1.5 N·m·s–1, for power, endurance, and nonathletes, respectively), whereas no group differences were observed for KF. The KE Q30 was significantly greater in power athletes, both in absolute terms and relative to peak EMG amplitude (9.8 ± 7.0, 5.9 ± 4.2, 4.4 ± 2.2 mV·ms and 1.7 ± 0.8, 1.1 ± 0.6, 0.9 ± 0.5 (mV·ms)/(mV) for power, endurance, and nonathletes, respectively), with no group differences in KF. The KE EMD tended to be shorter (P = .07) in power athletes during KE (71.0 ± 24.1, 87.8 ± 18.0, 88.4 ± 27.8 ms, for power, endurance, and nonathletes), with no group differences in KF.

Conclusions:

Pre- and early-pubertal power athletes have enhanced rate of muscle activation in specifically trained muscles compared with controls or endurance athletes, suggesting that specific training can result in muscle activation-pattern changes before the onset of puberty.

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Kerry E. Costello, Janie L. Astephen Wilson, William D. Stanish, Nathan Urquhart and Cheryl L. Hubley-Kozey

gastrocnemius, quadriceps, and hamstrings muscle activation and prolonged quadriceps and hamstrings activation through mid-stance were found at baseline in those who progressed. 23 Higher peak KFM, thought to indicate greater compressive loads on the joint, has been associated with progression of a structural

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Eleni Bassa, Dimitrios Patikas, Konstantinos Hatzikotoulas and Christos Kotzamanidis

We would like to comment on the paper by Dotan et al. (8) entitled “Child-adult differences in muscle activation—a review.” Dotan et al.’s review (8) in conjunction with the commentary of O’Brien et al. (20) constitutes an important contribution to the question “who are stronger: children or adults?” based on specific force comparisons between children and adults and not on absolute values. For simplification reasons, we would like to limit the context of this question to single-joint isometric and isokinetic contractions only. Hence, we will not discuss multi-joint dynamic actions.