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Manuel E. Hernandez, Erin O’Donnell, Gioella Chaparro, Roee Holtzer, Meltem Izzetoglu, Brian M. Sandroff and Robert W. Motl

Functional near-infrared spectroscopy was used to evaluate prefrontal cortex activation differences between older adults with multiple sclerosis (MS) and healthy older adults (HOA) during the performance of a balance- and attention-demanding motor task. Ten older adults with MS and 12 HOA underwent functional near-infrared spectroscopy recording while talking, virtual beam walking, or virtual beam walking while talking on a self-paced treadmill. The MS group demonstrated smaller increases in prefrontal cortex oxygenation levels than HOA during virtual beam walking while talking than talking tasks. These findings indicate a decreased ability to allocate additional attentional resources in challenging walking conditions among MS compared with HOA. This study is the first to investigate brain activation dynamics during the performance of balance- and attention-demanding motor tasks in persons with MS.

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Aaron England, Timothy Brusseau, Ryan Burns, Dirk Koester, Maria Newton, Matthew Thiese and Benjamin Chase

In adult performers, research suggests that mental representations (MRs) mediate performance of skilled movement. During adolescence, cortical brain areas responsible for generating MRs develop rapidly along with limb size, which, together, may affect movement and movement representations. The aim of this study was to examine the relationship between adolescent MRs and free-throw shooting expertise. Using structural dimensional analysis of MRs, skilled (n = 11) and less skilled (n = 11) participants sorted free-throw submovements according to their relatedness in movement execution. Data were analyzed using a hierarchical cluster analysis, factor analysis, and invariance test to examine between-group cluster comparisons. Cluster solutions for the skilled and less skilled participants were significantly variant (λ = 0.56). This method of measuring MRs distinguished expertise-related differences in MRs in an adolescent population. Findings may influence methods in which practitioners detect motor-planning faults, track development, and provide feedback to trainees.

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Astrid C.J. Balemans, Han Houdijk, Gilbert R. Koelewijn, Marjolein Piek, Frank Tubbing, Anne Visser-Meily and Olaf Verschuren

Background: It is questionable whether postures that are regarded as sedentary behavior in able-bodied persons evoke comparable physiological responses in adults with stroke or cerebral palsy (CP). This study aimed to compare metabolic demand and muscle activity in healthy controls, adults with stroke, and adults with CP during sedentary behavior and light physical activities. Methods: Seventy-one adults (45.6 [18.9] y, range 18–86) participated in this study, of which there were 18 controls, 31 with stroke, and 22 with CP. The metabolic equivalent of task (MET) and level of muscle activation were assessed for different sedentary positions (sitting supported and unsupported) and light physical activities (standing and walking). Results: During sitting supported and unsupported, people with mild to moderate stroke and CP show comparable MET and electromyographic values as controls. While sitting unsupported, people with severe stroke show higher METs and electromyographic values (P < .001), and people with severe CP only show higher METs compared with controls (P < .05) but all below 1.5 METs. Standing increased electromyographic values in people with severe stroke or CP (P < .001) and reached values above 1.5 METs. Conclusions: Physiologic responses during sedentary behavior are comparable for controls and adults with mild to moderate stroke and CP, whereas higher metabolic demands and muscle activity (stroke only) were observed in severely affected individuals.

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Alessandra Prioreschi and Lisa K. Micklesfield

Background: This study reported compliance with 24-hour physical activity and sedentary behavior guidelines, and associations with adiposity in the first 2 years of life. Methods: Participants (N = 119) were recruited from Soweto, South Africa. Visceral and subcutaneous abdominal adipose tissue was measured by ultrasound. Participation in 2 movement behaviors (physical activity and sedentary time) was reported by mothers. Differences in adiposity between those meeting each individual guideline, as well as the combination of both movement guidelines, compared with those not meeting the guidelines were assessed. Results: Only 5% of infants met the sedentary guidelines; however, 58% met the physical activity guidelines. Subcutaneous adipose tissue was significantly higher in those meeting the physical activity guideline (0.50 [0.01] vs 0.47 [0.01] cm, P = .03) compared with those not meeting the guideline. Meeting the screen time component of the sedentary guideline was associated with higher visceral adipose tissue (β = 0.96, P < .01), while meeting one guideline compared with meeting none was associated with higher subcutaneous adipose tissue (β = 0.05, P = .01). Conclusions: Most infants and toddlers from this low- to middle-income setting were not meeting sedentary behavior guidelines. Both behaviors were associated with abdominal adiposity, but not with body mass index z score; implying these movement behaviors may impact abdominal fat deposition rather than body size.

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Christina M. Patch, Caterina G. Roman, Terry L. Conway, Ralph B. Taylor, Kavita A. Gavand, Brian E. Saelens, Marc A. Adams, Kelli L. Cain, Jessa K. Engelberg, Lauren Mayes, Scott C. Roesch and James F. Sallis

Background: A common hypothesis is that crime is a major barrier to physical activity, but research does not consistently support this assumption. This article advances research on crime-related safety and physical activity by developing a multilevel conceptual framework and reliable measures applicable across age groups. Methods: Criminologists and physical activity researchers collaborated to develop a conceptual framework. Survey development involved qualitative data collection and resulted in 155 items and 26 scales. Intraclass correlation coefficients (ICCs) were computed to assess test–retest reliability in a subsample of participants (N = 176). Analyses were conducted separately by age groups. Results: Test–retest reliability for most scales (63 of 104 ICCs across 4 age groups) was “excellent” or “good” (ICC ≥ .60) and only 18 ICCs were “poor” (ICC < .40). Reliability varied by age group. Adolescents (aged 12–17 y) had ICCs above the .40 threshold for 21 of 26 scales (81%). Young adults (aged 18–39 y) and middle-aged adults (aged 40–65 y) had ICCs above .40 for 24 (92%) and 23 (88%) scales, respectively. Older adults (aged 66 y and older) had ICCs above .40 for 18 of 26 scales (69%). Conclusions: The conceptual framework and reliable measures can be used to clarify the inconclusive relationships between crime-related safety and physical activity.

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Connie L. Tompkins, Erin K. Shoulberg, Lori E. Meyer, Caroline P. Martin, Marissa Dennis, Allison Krasner and Betsy Hoza

Background: According to the US Institute of Medicine guideline, preschool-aged children should participate in ≥15 minutes of physical activity (PA) per hour or 3 hours per day over 12 hours. Examinations of PA guideline compliance to date averaged time spent in PA over several days; however, children could exceed the guideline on some days and not on others. Therefore, this cross-sectional study examined PA guideline compliance in preschool children based on number of minutes per hour (average method) and percentage of days the guideline was met (everyday method). Methods: PA was measured by accelerometry during the preschool day for up to 10 days in 177 children (59.3% males, M age = 4.23). Minutes per hour and percentage of time in light, moderate to vigorous, and total PAs were calculated. Percentage of days in compliance was determined by number of days in compliance (defined as the child active on average ≥15 min/h) divided by total accelerometer days. Results: Children engaged in PA, on average, 17.01 minutes per hour, suggesting that on average, children are meeting the guideline. However, children were only in compliance with the PA guideline 62.41% of assessment days. Conclusions: Findings demonstrate the importance of examining compliance with both the average and everyday methods to more accurately portray level of Institute of Medicine PA guideline compliance.

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Matthew J. Major, José L. Zavaleta and Steven A. Gard

Investigations have begun to connect leg prosthesis mechanical properties and user outcomes to optimize prosthesis designs for maximizing mobility. To date, parametric studies have focused on prosthetic foot properties, but not explicitly longitudinal stiffness that is uniquely modified through shock-absorbing pylons. The linear spring function of these devices might affect work performed on the body center of mass during walking. This study observed the effects of different levels of pylon stiffness on individual limb work of unilateral below-knee prosthesis users walking at customary and fast speeds. Longitudinal stiffness reductions were associated with minimal increase in prosthetic limb collision and push-off work, but inconsistent changes in sound limb work. These small and variable changes in limb work did not suggest an improvement in mechanical economy due to reductions in stiffness. Fast walking generated greater overall center of mass work demands across stiffness conditions. Results indicate limb work asymmetry as the prosthetic limb experienced on average 61% and 36% of collision and push-off work, respectively, relative to the sound limb. A series-spring model to estimate residuum and pylon stiffness effects on prosthesis energy storage suggested that minimal changes to limb work may be due to influences of the residual limb which dominate the system response.

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Layne Case and Joonkoo Yun

Despite the rising interest in intervention for children with autism spectrum disorder, the extent to which interventions are effective on gross motor outcomes is currently unknown. The purpose of this study was to analyze the effect of different intervention approaches on gross motor outcomes among children with autism spectrum disorder using meta-analysis. A total of 18 studies met the inclusion criteria for quantitative analysis. Pre- and posttest means and SDs were extracted to calculate effect sizes. Potential moderator variables were chosen based on important intervention characteristics. The results suggest that interventions have a large effect on gross motor outcomes among children with autism spectrum disorder (δ = 0.99, SE = 0.19, p < .001, 95% confidence interval [0.62, 1.36]). The interventions that were 16 total hours or longer had a significantly larger effect than those less than 16 hr. In addition, the interventions in experimental settings had significantly larger effects than the interventions in practical settings. Future interventions should consider intensity, including not only the duration of the intervention but also the intensity in which specific intervention goals are targeted.

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Aaron Derouin and Jim R. Potvin

Functional knee braces are frequently prescribed by physicians to ameliorate the function of individuals with anterior cruciate ligament (ACL) injuries. These braces have been shown in the literature to potentially enhance knee stability by augmenting muscle activation patterns and the timing of muscle response to perturbations. However, very few techniques are available in the literature to quantify how those modifications in lower-limb muscle activity influence stability of the knee. The aim of the present study was to quantify the effect of an off-the-shelf functional knee brace on muscle contributions to knee joint rotational stiffness in ACL-deficient and ACL-reconstructed patients. Kinematic, electromyography, and kinetic data were incorporated into an electromyography-driven model of the lower extremity to calculate individual and total muscle contributions to knee joint rotational stiffness about the flexion–extension axis, for 4 independent variables: leg condition (contralateral uninjured, unbraced ACL injured, and braced ACL injured); knee flexion (5°–10°, 20°–25°, and 30°–35°); squat stability condition (stable and unstable); and injury status (ACL deficient and ACL reconstructed). Participants had significantly higher (P < .05, η 2 = .018) total knee joint rotational stiffness values while wearing the brace compared with the control leg. A 2-way interaction effect between stability and knee flexion (P < .05, η 2 = .040) for total joint rotational stiffness was also found.

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Iva Obrusnikova, Haley M. Novak and Albert R. Cavalier

Adults with intellectual disability have significantly lower musculoskeletal fitness than their peers without a disability. Appropriate instructional strategies are needed to facilitate their acquisition and maintenance of musculoskeletal fitness. In this multiple-baseline across-participants single-subject study, the authors evaluated the effects of a multicomponent package that included a video-enhanced system of least-to-most prompts on the acquisition of 5 muscle-strengthening exercises in 3 women with mild intellectual disability, age 24–37 yr. Results show substantive gains in correct and independent performance of steps in the 5 exercises during the treatment condition. The improved performance was maintained 2 wk after the last treatment session and in a large YMCA gym. The study suggests that use of the video-enhanced system of least-to-most prompts can lead to improved acquisition and maintenance of muscle-strengthening exercises by adults with mild intellectual disability.