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Margaret McGladrey, Angela Carman, Christy Nuetzman and Nicole Peritore

Background: Rural counties in the United States face daunting structural issues that reduce their populations’ physical activity levels, including geographic isolation as well as deficits in infrastructure, public transportation, health care providers, and funding. Methods: Funding from the Centers for Disease Control and Prevention provided an opportunity to assess how Extension enhanced the collective impact of systems-level physical activity promotion programming through a multisectoral coalition in Clinton County, Kentucky. Results: The Extension-led coalition accomplished the 6 essential functions of a backbone support organization by identifying obesity as a critical local issue (function 1: providing overall strategic direction), developing a multisectoral coalition (function 2: facilitating dialog between partners), compiling data on the county’s physical activity infrastructure (function 3: managing data collection and analysis), creating communication channels (function 4: handling communication), organizing community awareness events (function 5: coordinating community outreach), and securing additional grants (function 6: mobilizing funding). The average rating of Extension’s leadership across multiple dimensions by 3 coalition members in a postproject survey was “excellent” on a 5-point Likert scale. Conclusions: Extension is well positioned through their mission, broad community engagement, data collection, needs assessment, community and academic relationships, and embeddedness in local communities to serve as the backbone support organizations for rural physical activity promotion coalitions.

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Mark S. Tremblay

Background: Emerging research shows that the composition of movement behaviors throughout the day (physical activities, sedentary behaviors, sleep) is related to indicators of health, suggesting previous research that isolated single movement behaviors maybe incomplete, misleading, and/or unnecessarily constrained. Methods: This brief report summarizes evidence to support a 24-hour movement behavior paradigm and efforts to date by a variety of jurisdictions to consult, develop, release, promote, and study 24-hour movement guidelines. It also introduces and summarizes the accompanying series of articles related specifically to 24-hour movement guidelines for the early years. Results: Using robust and transparent processes, Canada, Australia, New Zealand, South Africa, and the World Health Organization have developed and released 24-hour movement guidelines for the early years: an integration of physical activity, sedentary behavior, and sleep. Other countries are exploring a similar approach and related research is expanding rapidly. Articles related to guideline development in South Africa, the United Kingdom, Australia, and by the World Health Organization are a part of this special series. Conclusions: A new paradigm employing 24-hour movement guidelines for the early years that combines recommendations for movement behaviors across the whole day is gaining momentum across the globe.

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Brigid M. Lynch, Andrea Ramirez Varela and Terry Boyle

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Seiichiro Takei, Kuniaki Hirayama and Junichi Okada

Purpose: The optimal load for maximal power output during hang power cleans (HPCs) from a mechanical perspective is the 1-repetition-maximum (1RM) load; however, previous research has reported otherwise. The present study thus aimed to investigate the underlying factors that determine optimal load during HPCs. Methods: Eight competitive Olympic weight lifters performed HPCs at 40%, 60%, 70%, 80%, 90%, 95%, and 100% of their 1RM while the ground-reaction force and bar/body kinematics were simultaneously recorded. The success criterion during HPC was set above parallel squat at the receiving position. Results: Both peak power and relative peak power were maximized at 80% 1RM (3975.7 [439.1] W, 50.4 [6.6] W/kg, respectively). Peak force, force at peak power, and relative values tended to increase with heavier loads (P < .001), while peak system velocity and system velocity at peak power decreased significantly above 80% 1RM (P = .005 and .011, respectively). There were also significant decreases in peak bar velocity (P < .001) and bar displacement (P < .001) toward heavier loads. There was a strong positive correlation between peak bar velocity and bar displacement in 7 of 8 subjects (r > .90, P < .01). The knee joint angle at the receiving position fell below the quarter-squat position above 70% 1RM. Conclusions: Submaximal loads were indeed optimal for maximal power output for HPC when the success criterion was set above the parallel-squat position. However, when the success criterion was defined as the quarter-squat position, the optimal load became the 1RM load.

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Daniel Boullosa

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Paddy C. Dempsey, Chuck E. Matthews, S. Ghazaleh Dashti, Aiden R. Doherty, Audrey Bergouignan, Eline H. van Roekel, David W. Dunstan, Nicholas J. Wareham, Thomas E. Yates, Katrien Wijndaele and Brigid M. Lynch

Background: Recent updates to physical activity guidelines highlight the importance of reducing sedentary time. However, at present, only general recommendations are possible (ie, “Sit less, move more”). There remains a need to investigate the strength, temporality, specificity, and dose–response nature of sedentary behavior associations with chronic disease, along with potential underlying mechanisms. Methods: Stemming from a recent research workshop organized by the Sedentary Behavior Council themed “Sedentary behaviour mechanisms—biological and behavioural pathways linking sitting to adverse health outcomes,” this paper (1) discusses existing challenges and scientific discussions within this advancing area of science, (2) highlights and discusses emerging areas of interest, and (3) points to potential future directions. Results: A brief knowledge update is provided, reflecting upon current and evolving thinking/discussions, and the rapid accumulation of new evidence linking sedentary behavior to chronic disease. Research “action points” are made at the end of each section—spanning from measurement systems and analytic methods, genetic epidemiology, causal mediation, and experimental studies to biological and behavioral determinants and mechanisms. Conclusion: A better understanding of whether and how sedentary behavior is causally related to chronic disease will allow for more meaningful conclusions in the future and assist in refining clinical and public health policies/recommendations.

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Yuko Kuramatsu, Yuji Yamamoto and Shin-Ichi Izumi

This study investigated the sensorimotor strategies for dynamic balance control in individuals with stroke by restricting sensory input that might influence task accomplishment. Sit-to-stand movements were performed with restricted vision by participants with hemiparesis and healthy controls. The authors evaluated the variability in the position of participants’ center of mass and velocity, and the center-of-pressure position, in each orthogonal direction at the lift-off point. When vision was restricted, the variability in the mediolateral center-of-pressure position decreased significantly in individuals with hemiparesis, but not in healthy controls. Participants with hemiparesis adopted strategies that explicitly differed from those used by healthy individuals. Variability may be decreased in the direction that most requires accuracy. Individuals with hemiparesis have been reported to have asymmetrical balance deficits, and that meant they had to prioritize mediolateral motion control to prevent falling. This study suggests that individuals with hemiparesis adopt strategies appropriate to their characteristics.