The International Consensus Conference on Physical Activity Guidelines for Adolescents convened to review the effects of physical activity on the health of adolescents, to establish age-appropriate physical activity guidelines, and to consider how these guidelines might be implemented in primary health care settings. Thirty-four invited experts and representatives of scientific, medical, and governmental organizations established two main guidelines. First, all adolescents should be physically active daily or nearly every day as part of their lifestyles. Second, adolescents should engage in three or more sessions per week of activities that last 20 min or more and that require moderate to vigorous levels of exertion. Available data suggest that the vast majority of U.S. adolescents meet the first guideline, but only about two thirds of boys and one half of girls meet the second guideline. Physical activity has important effects on the health of adolescents, and the promotion of regular physical activity should be a priority for physicians and other health professionals.
James F. Sallis and Kevin Patrick
Maureen Lucas and Cynthia J. Heiss
Protein recommendations by some professional organizations for young adults engaged in resistance training (RT) are higher than the recommended dietary allowance (RDA), but recommendations for resistance-training older adults (>50 years old) are not well characterized. Some argue that the current RDA is adequate, but others indicate increased protein needs. Although concerns have been raised about the consequences of high protein intake, protein intake above the RDA in older adults is associated with increased bone-mineral density when calcium intake is adequate and does not appear to compromise renal health in older individuals with normal renal function. Individual protein needs for older adults in RT are likely highly variable according to health and training regimen, but an intake of 1.0–1.3 g · kg−1 · day−1 should adequately and safely meet the needs of older adults engaged in RT, provided that their energy needs are met.
Harold A. Riemer and Packianathan Chelladurai
The development of the l5-dimension, 56-item Athlete Satisfaction Questionnaire (ASQ) was based on Chelladurai and Riemer’s (1997) classification of facets of athlete satisfaction. Qualitative procedures included item generation, expert judgment, and independent placement of items in relevant facets. Quantitative procedures, item-to-total correlations, exploratory and confirmatory factor analyses, involving 172 undergraduate students and 614 Canadian university athletes, confirmed the construct validity of the scale. Correlations between the ASQ’s subscales and scales of commitment and negative affectivity provided evidence of criterion-related validity. Reliability estimates (Cronbach’s alpha) ranged from .78 to .95. The 15 facets of ASQ encompassed salient aspects of athletic participation, performance (both individual and team), leadership, the team, the organization, and the athlete.
Gerrit Jan van Ingen Schenau, Maarten F. Bobbert and Arnold de Haan
This target article addresses the role of storage and reutilization of elastic energy in stretch-shortening cycles. It is argued that for discrete movements such as the vertical jump, elastic energy does not explain the work enhancement due to the prestretch. This enhancement seems to occur because the prestretch allows muscles to develop a high level of active state and force before starting to shorten. For cyclic movements in which stretch-shortening cycles occur repetitively, some authors have claimed that elastic energy enhances mechanical efficiency. In the current article it is demonstrated that this claim is often based on disputable concepts such as the efficiency of positive work or absolute work, and it is argued that elastic energy cannot affect mechanical efficiency simply because this energy is not related to the conversion of metabolic energy into mechanical energy. A comparison of work and efficiency measures obtained at different levels of organization reveals that there is in fact no decisive evidence to either support or reject the claim that the stretch-shortening cycle enhances muscle efficiency. These explorations lead to the conclusion that the body of knowledge about the mechanics and energetics of the stretch-shortening cycle is in fact quite lean. A major challenge is to bridge the gap between knowledge obtained at different levels of organization, with the ultimate purpose of understanding how the intrinsic properties of muscles manifest themselves under in-vivo-like conditions and how they are exploited in whole-body activities such as running. To achieve this purpose, a close cooperation is required between muscle physiologists and human movement scientists performing inverse and forward dynamic simulation studies of whole-body exercises.
relationships, opportunity) affect psychological variables such as job satisfaction, morale, and organizational commitment, which in turn influence and predict decisions to persist in a workplace or seek employment elsewhere. Johnsrud and colleagues ( Johnsrud & Des Jarlais, 1994 ; Johnsrud & Heck, 1994
Chevelle M.A. Davis, Tetine L. Sentell, Juliana Fernandes de Souza Barbosa, Alban Ylli, Carmen-Lucia Curcio and Catherine M. Pirkle
By 2050, the global population of individuals aged 60 years and older (“older adults”) is projected to reach two billion, with an estimated 80% of all older people living in low- and middle-income countries (LMIC; World Health Organization [WHO], 2018 ). Middle-income countries (MIC)—defined as
Amanda Ebert and Donna L. Goodwin
( Karkaletsi, Skordilis, Evaggelinou, Grammatopoulou, & Spanaki, 2012 ; Peers, 2018 ; Standal, 2008 ; Standal, Nyquist, & Mong, 2018 ). For APA professionals in inclusive service delivery positions, the sundry of multidisciplinary influences creates a landscape composed of diverse personnel, organizational
Shannon S.C. Herrick and Lindsay R. Duncan
are often the main thing that will stop me from going to a gym, event, facility, etc.” In this study, 200 self-identified transgender participants expressed how the binary gender organization of locker rooms inextricably complicated their locker-room experiences. Salem, a 22-year-old White queer
Terry Marsh, Kathryn Pitkin Derose and Deborah A. Cohen
Parks provide numerous opportunities for physical activity (PA). Previous studies have evaluated parks’ physical features, but few have assessed how park staff influence PA.
We conducted semistructured interviews with 49 park directors, focusing on perceptions of their role, park programs, marketing and outreach, external collaborations, and PA promotion. Directors also completed a questionnaire providing demographics, education and training, and other personal characteristics.
Park directors’ descriptions of their roles varied widely, from primarily administrative to emphasizing community interaction, though most (70% to 80%) reported offering programs and community interaction as primary. Including PA in current programs and adding PA-specific programs were the most commonly reported ways of increasing PA. Also noted were facility and staffing improvements, and conducting citywide marketing. Many directors felt inadequately trained in marketing. Most parks reported community collaborations, but they appeared fairly superficial. An increasing administrative burden and bureaucracy were recurring themes throughout the interviews.
Staff training in marketing and operation of PA programs is needed. Partnerships with health departments and organizations can help facilitate the PA promotion potential of parks. As there are competing views of how parks should be managed, standardized benchmarks to evaluate efficiency may help to optimize usage and PA promotion.
Etienne Guillaud, Martin Simoneau, Gabriel Gauthier and Jean Blouin
The control of goal-directed arm movements performed during whole-body displacements is far from being understood. Recent studies suggested that the compensatory arm movements that allow individuals to preserve hand-in-space trajectory during unexpected body motion are controlled by sensorimotor, automatic-like processes. We tested this hypothesis comparing both the accuracy of movements directed towards body-fixed or Earth-fixed target during body rotations and the amount of interference of the reaching tasks on a concurrent cognitive task. Participants reached for a memorized 55 cm distant straight-ahead target in darkness which was about 20 cm lower than the initial finger position. The target was either body-fixed or Earth-fixed. At reaching onset, participants could be rotated in yaw. The concurrent task consisted of a verbal reaction time (RT) to an auditory stimulus. RTs increased when participants reached for the target while they were rotated. However, this increase was not significantly different for body-fixed and Earth-fixed targets. Reaching accuracy was greater for body-fixed than for Earth-fixed targets. A control experiment suggested that the errors in the Earth-fixed target condition arose from a difficulty in the organization of movements which necessitate both the production of active forces at the shoulder joint (to compensate for body rotation) and a concomitant decrease of muscular activation to lower the arm during reaching movements. These findings suggest that reaching for Earth-fixed or body-fixed targets during body rotation cannot be considered as being purely automatic tasks.