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Zong-Ming Li, Shouchen Dun, Daniel A. Harkness and Teresa L. Brininger

The purpose of the current study was to examine motion enslaving characteristics of multiple fingers during isolated flexion of the distal interphalangeal joints. Because the distal interphalangeal joints are flexed by multiple tendons of the single flexor digitorum profundus, the current experimental design provided a unique advantage to understand inter-finger enslaving effects due to the flexor digitorum profundus. Eight subjects were instructed to flex the distal inter-phalangeal joint of each individual finger from the fully extended position to the fully flexed position as quickly as possible. Maximal angular displacements, velocities, or accelerations of individual fingers were used to calculate the enslaving effects. An independence index, defined as the ratio of the maximal displacement of a master finger to the sum of the maximal displacements of the master and slave fingers, was used to quantify relative independence of each finger. The angular displacements of the index, middle, ring, and little fingers were 68.6° (±7.7), 68.1° (±10.1), 68.1° (±9.7), and 74.7° (±13.3), respectively. The motion of a master finger was invariably accompanied by motion of 1 or 2 slave fingers. Angular displacements of master and slave fingers increased to maximum values with time monotonically. Velocity curves demonstrated bell-shaped profile, and the acceleration curves were sinusoidal. Enslaving effects were generated mainly on the neighboring fingers. The amount of enslaving on the middle and ring fingers exceeded more than 60% of their own maximum angular displacements when a single adjacent finger moved. The index finger had the highest level of independence as indicated by the lowest enslaving effects on other fingers or by other fingers. The independence indices of the index, middle, ring, and little fingers were 0.812 (±0.070), 0.530 (±0.051), 0.479 (±0.099), and 0.606 (±0.148), respectively. In all tasks, motion of slave fingers always lagged with respect to the master finger. Time delays, on average, ranged from 7.8 (±5.0) to 35.9 (±22.1) ms. Our results suggest that there exist relatively large enslaving effects among the compartments of the flexor digitorum profundus, and functional independence of fingers in daily activities is likely enhanced through synergistic activities of multiple muscles, including flexors and extensors.

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Brittany N. Kiefer, Kyle E. Lemarr, Christopher C. Enriquez, Kristin A. Tivener and Todd Daniel

Even though adaption of the Voodoo Floss Band is gaining momentum, evidence-based literature on its effectiveness remains sparse. The purpose of this quantitative observational design study was to investigate the effects of the Voodoo Floss Band on soft-tissue flexibility and perception of movement. A repeated-measures ANOVA with between-subjects factor demonstrated both groups significantly improved GH flexion range of motion from pretest to post-test but there was not a statistically significant difference between the groups. Perceptions of flexibility increased more for the Voodoo Floss Band group, demonstrating a psychological increase in GH flexion, but not a physical increase.

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Cheng-Feng Lin, Wan-Chin Lee, Yi-An Chen and Bih-Jen Hsue

Fatigue in ballet dancers may lead to injury, particularly in the lower extremities. However, few studies have investigated the effects of fatigue on ballet dancers’ performance and movement patterns. Thus, the current study examines the effect of fatigue on the balance, movement pattern, and muscle activities of the lower extremities in ballet dancers. Twenty healthy, female ballet dancers performed releve on demi-pointe before and after fatigue. The trajectory of the whole body movement and the muscle activities of the major lower extremity muscles were recorded continuously during task performance. The results show that fatigue increases the medial-lateral center of mass (COM) displacement and hip and trunk motion, but decreases the COM velocity and ankle motion. Moreover, fatigue reduces the activities of the hamstrings and tibialis anterior, but increases that of the soleus. Finally, greater proximal hip and trunk motions are applied to compensate for the effects of fatigue, leading to a greater COM movement. Overall, the present findings show that fatigue results in impaired movement control and may therefore increase the risk of dance injury.

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Clément Theurillat, Ilona Punt, Stéphane Armand, Alice Bonnefoy-Mazure and Lara Allet

of motion (ROM). A limited ankle dorsiflexion can increase re-injuries. 5 Recurrent ankle sprains can lead to chronic ankle instability or degenerative bone disorder. 6 , 7 Therefore, a precise clinical evaluation of ROM and a tailored rehabilitation program are necessary to prevent recurrent ankle

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Gustavo Ramos Dalla Bernardina, Tony Monnet, Heber Teixeira Pinto, Ricardo Machado Leite de Barros, Pietro Cerveri and Amanda Piaia Silvatti

Optoelectronic motion capture systems (MOCAP), such as Vicon (Oxford Metrics Ltd, Oxford, United Kingdom), Elite (BTS, Milan, Italy), Qualisys (Göteborg, Sweden), Motion Analysis (Motion Analysis Corp, Santa Rosa, CA), and OptiTrack (NaturalPoint, Inc, Corvallis, OR), are considered to be the

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Kornelius Kraus, Elisabeth Kraus, Boris Gojanovic and Francois Fourchet

motion (ROM) measurements are a critical component in preparticipation examinations or muscle function testing procedures during the rehabilitation process. The diagnostic results are used to guide the treatment or program design. 1 – 3 Used as a regular monitoring measurement, ROM helps to evaluate the

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Elisa S. Arch, Sarah Colón and James G. Richards

Thirty-three percent of women do not meet physical activity guidelines. 1 A study conducted in 2015 found that 17% of women said that their breasts prevented them from participating in physical activity because, for example, they experienced excessive breast and bra motion during physical activity

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Justin M. Stanek, Jake Parish, Richard Rainville and Jeffrey G. Williams

Key Points ▸ Tibial rotation is important for normal knee and ankle function. ▸ Rotational motion at the tibia is rarely quantified in the clinical environment. ▸ Tibial rotation can be quickly and reliably assessed using a smartphone. ▸ Consistency in methodology and device are imperative for

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Ben Langley, Mary Cramp and Stewart C. Morrison

Traditional running-injury paradigms have been challenged within the literature, 1 yet still underpin running shoe design. As such, running shoes are still designed with stability and cushioning features that are thought to influence the rate and/or magnitude of foot motion and impact loading. 2

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Jeffrey G. Williams, Lauryn Darnall and Conrad Schumann

Key Points ▸ Spinal range of motion among players is suspected to be compensatory to tightness in the posterior shoulder. ▸ No studies have tested this relationship. ▸ No relationship was observed between thoracolumbar and glenohumeral ranges of motion. Throwing a baseball demands properly