The U.S. Department of Health and Human Services, the Subcommittee of the President’s Council on Fitness, Sports & Nutrition and the American College of Sports Medicine, among others, recommend that children and youth participate in 60 minutes a day of moderate to vigorous physical activity (PA) [1, 2]. It is further recommended that the content of the PA include aerobic, muscle, and bone-strengthening activities . Similar recommendations have been put forward to stimulate the participation of children with disability in sports and recreational activities as well as to achieve the same expected 60 minutes-a-day of moderate-to-vigorous PA (MVPA) . Recommendations reside on the fact that PA provides numerous health benefits for children such as helping regulate blood sugar, insulin, lipids and blood pressure, maintaining a healthy weight, developing stronger bones, building muscle mass and improving physical fitness [2, 4, 5]. Additionally PA is associated with increased self-efficacy, less depression and anxiety and ultimately a higher quality of life .
Currently, 58% of children ages 6-11 y are not meeting these recommended guidelines . And, available studies in children and adolescents with physical and/or cognitive disability suggest that their participation in PA may be lower [7–11] and does not meet the recommended minutes . Low participation in PA has been linked to the increasing prevalence of obesity in youth with disability .
Prader-Willi Syndrome (PWS) is a rare congenital disease stemming from an alteration or the lack of expression of the paternal chromosome 15 in the locus 13-15q. This syndrome is the best-characterized form of childhood obesity and people with PWS have abnormally high body fat percentage and low lean mass . In addition, having PWS is associated with innate lethargy, delayed motor development, lower motor competencies, lower cognitive function, and behavioral challenges, with most individuals presenting with physical and intellectual disability . Children and adults with this condition exhibit low levels of ambulatory PA [14, 15], little vigorous PA, and appear to perform few activities aimed at improving muscular strength . In children with PWS, more PA has been associated with lower body mass index (BMI), and reduced engagement in self-injury behavior common to PWS such as skin picking . To date, four approaches to promoting PA in persons with PWS have been evaluated: two strength-training routines delivered at home for children [18, 19], and a walking and an at home strengthening programs for adults [20, 21]. Although these programs were successful at improving body composition, spontaneous physical activity and general fitness levels, none of these approaches considered the multiple dimensions of physical fitness (e.g., aerobic endurance, strength, flexibility), the development and improvement of motor competencies, or the concept of developing a fun family PA routine.
Social Cognitive Theory was the theoretical framework used to guide the development and implementation of this physical activity intervention . Self-efficacy is a focal determinant of Social Cognitive Theory and has often been a key target of PA interventions . For individuals to adopt and maintain a healthy lifestyle including behaviors such as PA, the person needs to have the self-regulatory skills and the confidence to regulate the behavior . Self-regulatory skills (i.e. self-monitoring, planning, coping with barriers) have been related to improving PA behavior by increasing adherence in adults  and often are included in interventions that employ a social cognitive theory framework .
Individuals may manage or regulate their own behavior and/or have another individual serve as a proxy to manage their behavior . In children, parents may serve as a proxy and aid in the management and regulation of their child’s PA by scheduling opportunities for PA and providing equipment and/or transportation. Further, it might be speculated that in children with disability the parent may take a more active role in regulating the child’s behavior. The primary assumption of Social Cognitive Theory is that behavior, environment, and the person are reciprocally linked . A key part of children’s environment involves the influence from parents as they play an essential role in the development of their children’s behaviors, attitudes, and values. In fact, previous studies have shown that parental influences are associated with children being more physically active . Parents have the potential not only to serve as proxy agents for their children’s PA but also to directly influence their children’s perceptions and behaviors. By targeting aspects of the person (e.g., PA self-efficacy) and the environment (e.g., social influences received from parents), an associated change in the child’s physical activity may emerge.
Successful approaches to increase PA in children
In children without disability, only a small number of interventions have been designed to improve motor skills [30, 31] since children who are more proficient in different motor domains (e.g., agility, balance, coordination, bilateral coordination, muscle strength, and aerobic endurance) are likely to be more physically active [32–34]. Activity cards or manuals containing progressive games and exercises have been successfully used in school settings and after school programs to increase MVPA and improve cardiovascular fitness [35, 36]. Most recently, interactive console-based games have been used to increase PA [37, 38] and even promote weight loss . In those with disability, the use of interactive console-based games seems a promising area of study as positive results in gross motor function have been shown for programs in children with cerebral palsy [40, 41] as well as Down syndrome .
Studies targeting lifestyle changes in children with obesity, inclusion of the family has been identified as a key component in effective interventions . In fact, in children with disability, family participation in PA has been shown to be a positive predictor of the child’s PA . Unfortunately, only a few studies have explored the feasibility of family interventions [44–46]; some interventions have targeted solely the parents as agents of change [47–49] and other interventions have included parent-child dyads participating in home-based PA programs [50, 51]. Co-activity, in which parents and children participate in physical activity together, is positively associated with PA in children , and thus appears to be important to target in a PA intervention. A recent report on strategies to promote PA in youth highlighted the need to test strategies that can take place at home and involve the parents or family .
The development of the active play @ home curriculum
Considering the abilities, needs, constraints, and preferences of children with PWS and their parents as well as previous intervention approaches that proved successful in this population [18, 19] we developed a home-based PA curriculum called Active Play @ Home. This well-rounded and varied PA curriculum includes all the essential exercise components recommended in the national guidelines (progressive games and exercises targeting cardiovascular fitness, muscular strength and endurance) while also targeting motor skill competencies. In addition, the curriculum incorporates the use of interactive console-based games that were carefully chosen to stimulate fitness components as well as specific motor skill competencies. The curriculum therefore blends more traditional playground games and exercises with interactive console-based games. The inclusion of the interactive console-based games aims to provide the children with a choice of activities that can be performed indoors while the playground games can be played outdoors. The curriculum is designed to involve an adult leader and one child; however, all activities can be played with more than one child in the home environment.
The goal of the Active Play @ Home study is to determine if a parent-led PA curriculum incorporating playground games and interactive console-based games can increase levels of PA and lead to positive motor and health-related outcomes in children with PWS and in children without the syndrome but who are obese. Changes in PA and motor and health-related parameters will be evaluated in these two groups in comparison to control groups following a 24-week PA intervention. The primary hypothesis is that an age-appropriate home-based PA intervention will increase PA levels in children with and without PWS. The secondary hypotheses include the following: 1) motor proficiency, central sensory reception and integration, and body composition will significantly improve in children, with and without PWS, following completion of the home-based PA intervention, and 2) self-efficacy and quality of life will increase significantly in children, with and without PWS, who complete the home-based PA intervention.