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James W. Roberts

Investigations of visually guided target-directed movement frequently adopt measures of within-participant spatial variability to infer the contribution of planning and control. The present study aims to verify this current trend by exploring the distribution of displacements at kinematic landmarks with a view to understand the potential sources of variability. Separate sets of participants aiming under full visual feedback conditions revealed a comparatively normal distribution for the displacements at peak velocity and movement end. However, there was demonstrable positive skew in the displacement at peak acceleration and a significant negative skew at peak deceleration. The ranges of the distributions as defined by either ±1SD or ±34.13th percentile (equivalent to an estimated 68.26% of responses) also revealed differences at peak deceleration. These findings indicate that spatial variability in the acceleration domain features highly informative systematic, as well as merely inherent, sources of variability. Implications for the further quantification of trial-by-trial behavior are discussed.

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Etem Curuk, Yunju Lee and Alexander S. Aruin

The authors investigated anticipatory postural adjustments in persons with unilateral stroke using external perturbations. Nine individuals with stroke and five control subjects participated. The electromyographic activity of 16 leg and trunk muscles was recorded. The onsets of muscle activity during the anticipatory phase of postural control were analyzed. The individuals with stroke did not show an anticipatory activation of leg and trunk muscles on the affected side; instead, the muscle onsets were seen after the perturbation, during the balance restoration phase. However, an anticipatory activation of muscles on the unaffected side was seen in individuals with stroke, and it was observed earlier compared with healthy controls (p < .05). The individuals with stroke showed a distal to proximal order of anticipatory activation of muscles on the unaffected side. The outcome of the study provides a basis for future investigations regarding ways of improving balance control in people with stroke.

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Eric Foch and Clare E. Milner

It is unknown if female runners who have sustained multiple iliotibial band syndrome occurrences run differently compared with runners who developed the injury once or controls. Therefore, the purpose of this study was to determine if differences existed in coordination patterns and coordination variability among female runners with recurrent iliotibial band syndrome, 1 iliotibial band syndrome occurrence, and controls. Overground running trials were collected for 36 female runners (n = 18 controls). Lower extremity coordination patterns were examined during running via a vector coding analysis. Coordination variability was calculated via the ellipse area method. Separate 1-way (group) Kruskal–Wallis tests were performed to compare each coordination pattern and coordination variability. Lower extremity coordination between frontal plane hip–transverse plane hip, frontal plane pelvis–frontal plane thigh, and frontal plane thigh–transverse plane shank was similar among groups and so may not be related to the risk of iliotibial band syndrome. Runners with 1 iliotibial band syndrome occurrence demonstrated greater coordination variability for 2 of 3 couplings compared with both controls and runners with recurrent iliotibial band syndrome. Thus, the number of previous injury episodes may influence coordination variability in female runners with a history of iliotibial band syndrome.

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Ljudmila Zaletelj

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Danny M. Pincivero, Rachael R. Polen and Brittany N. Byrd

The objective of the present study was to examine the relationship between maximal effort force production and anthropometric measures of upper-arm volume. Thirty healthy young participants (15 women) performed 5 isokinetic concentric and eccentric maximal effort elbow flexor/extensor contractions on separate days. Measures of arm length, circumference, and skinfold/subcutaneous fat thickness were used to obtain a measure of arm volume, modeled as 2 separate right-angle frustra. Single-variable regression analyses demonstrated significant (P < .001) second-order polynomial relationships between maximal effort elbow flexor and extensor force with arm volume (r 2 = .63–.86). The major findings demonstrated that strong and positive relations between maximal force production and estimates of limb volume can be observed using nonlinear modeling and a closer geometric representation of the exercising limb.

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Xihe Zhu and Justin A. Haegele

The purpose of this study was to examine reactivity to accelerometer measurement in children with visual impairments (VI), their sighted siblings, and their parents. A sample of 66 participants (including 22 children with VI, 22 siblings, and 22 parents) completed a demographic survey and wore triaxial accelerometers for at least 4 consecutive days for 8 hr. An analysis of covariances with repeated measures was conducted, controlling for participant gender. Children with VI had 8.1% less moderate to vigorous physical activity time on Day 1 than Days 2–4 average. Their sighted siblings and parents had 7.8% and 7.1% more moderate to vigorous physical activity time on Day 1 than their Days 2–4 average, respectively. The reactivity percentage for parents and children without VI is consistent with existing literature. However, an inverse reactivity for children with VI was found, which is a unique contribution to the literature and will have implications for researchers using accelerometers for this population.

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Kevin Deschamps, Giovanni Matricali, Maarten Eerdekens, Sander Wuite, Alberto Leardini and Filip Staes

Foot structure and kinematics have long been considered as risk factors for foot and lower-limb running injuries. The authors aimed at investigating foot joint kinetics to unravel their receptive and propulsive characteristics while running barefoot, both with rearfoot and with midfoot striking strategies. Power absorption and generation occurring at different joints of the foot in 6 asymptomatic adults were calculated using both a 3-segment and a 4-segment kinetic model. An inverse dynamic approach was used to quantify mechanical power. Major power absorption and generation characteristics were observed at the ankle joint complex as well as at the Chopart joint in both the rearfoot and the midfoot striking strategies. The power at the Lisfranc joint, quantified by the 4-segment kinetic model, was predominantly generated in both strategies, and at the toes, it was absorbed. The overall results show a large variability in the receptive and propulsive characteristics among the analyzed joints in both striking strategies. The present study may provide novel insight for clinical decision making to address foot and lower-limb injuries and to guide athletes in the adoption of different striking strategies during running.

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Wesley J. Wilson and K. Andrew R. Richards

Occupational socialization theory has been used to understand the recruitment, education, and socialization of physical education teachers for nearly 40 yr. It has, however, only recently been applied to the study of adapted physical education teachers. The purpose of this descriptive case study was to understand the socialization of preservice teachers in an adapted physical education teacher education graduate-level program. Participants included 17 purposefully selected preservice teachers (5 male and 12 female) enrolled in a yearlong graduate-level adapted physical education teacher education program. Qualitative data were collected using interviews, reflective journaling, and field notes taken during teaching and coursework observations. Data analysis resulted in the construction of 3 themes: overcoming contextual challenges to meet learners’ needs, the importance of field-based teacher education, and coping with the challenges of marginalization. The discussion connects to and advances occupational socialization theory in adapted physical education and suggests that professional socialization may have a more profound influence on preservice adapted physical education teachers than on their physical education counterparts.

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Ana F. Silva, Pedro Figueiredo, Sara Morais, João P. Vilas-Boas, Ricardo J. Fernandes and Ludovic Seifert

This study aimed to examine young swimmers’ behavioral flexibility when facing different task constraints, such as swimming speed and stroke frequency. Eighteen (five boys and 13 girls) 13- to 15-year-old swimmers performed a 15 × 50-m front crawl with five trials, at 100%, 90%, and 70% each of their 50 m maximal swimming speed and randomly at 90%, 95%, 100%, 105%, and 110% of their preferred stroke frequency. Seven aerial and six underwater cameras were used to assess kinematics (one cycle), with upper-limb coordination computed through a continuous relative phase and index of coordination. A cluster analysis identified six patterns of coordination used by swimmers when facing various speed and stroke frequency constraints. The patterns’ nature and the way the swimmers shifted between them are more important than getting the highest number of patterns (range of repertoire), that is, a change in the motor pattern in order to adapt correctly is more important than being able to execute a great number of patterns.

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Tomoko Aoki, Hayato Tsuda and Hiroshi Kinoshita

The purpose of this study was to examine finger motor function in terms of temporal and force characteristics during rapid single-finger tapping in older adults. Ten older and 10 young males performed maximum frequency tapping by the index, middle, ring, or little finger. Nontapping fingers were maintained in contact with designated keys during tasks. Key-contact force for each of the fingers was monitored using four force transducers. The older subjects had slower tapping rates of all fingers during single-finger tapping than the young subjects. The average forces exerted by the nontapping fingers were larger for the older subjects than for the young subjects during tapping with the ring and little fingers. The ranges of the nontapping finger forces were larger for the older subjects during tapping by the middle, ring, and little fingers than for the young subjects. Thus, the motor abilities of the fingers evaluated by rapid single-finger tapping decline in older adults compared with young adults in terms of both movement speed and finger independence.