Children and adolescents with Down syndrome, physical fitness and physical activity

Available online at www.sciencedirect.com Journal of Sport and Health Science 2 (2013) 47e57 www.jshs.org.cn Review Children and adolescents with D...
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Available online at www.sciencedirect.com

Journal of Sport and Health Science 2 (2013) 47e57 www.jshs.org.cn

Review

Children and adolescents with Down syndrome, physical fitness and physical activity Ken Pitetti a,*, Tracy Baynard b, Stamatis Agiovlasitis c a

Department of Physical Therapy, College of Health Professions, Wichita State University, Wichita, KS 67260-0043, USA b Department of Kinesiology & Nutrition, University of Illinois at Chicago, Chicago, IL 60612, USA c Department of Kinesiology, Mississippi State University, Mississippi State, MS 39762, USA Received 8 July 2012; revised 7 September 2012; accepted 26 September 2012

Abstract Children (5e12 years) and adolescents (13e19 years) with Down syndrome (DS) possess a set of health, anatomical, physiological, cognitive, and psycho-social attributes predisposing them to limitations on their physical fitness and physical activity (PA) capacities. The paucity of studies and their conflicting findings prevent a clear understanding and/or substantiation of these limitations. The purpose of this article was to review the measurement, determinants and promotion of physical fitness and PA for youth (i.e., children and adolescents) with DS. The existing body of research indicates that youth with DS: 1) have low cardiovascular and muscular fitness/exercise capacity; 2) demonstrate a greater prevalence of overweight and obesity; 3) a large proportion do not meet the recommended amount of daily aerobic activity; and 4) their PA likely declines through childhood and into adolescence. Future research should focus on: 1) strength testing and training protocols; 2) methodologies to determine PA levels; and 3) practical interventions to increase PA. Copyright Ó 2012, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved. Keywords: Activity; Adolescents; Children; Down syndrome; Fitness

1. Introduction 1.1. Background and genetics The condition of Down syndrome (DS) was first described in a clinical lecture report delivered in 1866 by the British physician, John Langdon Down, entitled “Observation on the ethnic classification of Mongoloid idiots”.1 Dr. Down used the derogatory term “Mongoloid” because children with DS

* Corresponding author. E-mail address: [email protected] (K. Pitetti) Peer review under responsibility of Shanghai University of Sport

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displayed facial features (e.g., epicanthal fold) that shared similarities with the prevailing erroneous ethnic theory established by the German anatomist, Johann Friedrich Blumenbach.2 Catalyzed by editorials in The Lancet, together with political pressure by advocacy groups and parental organizations in the 1960s, the term “mongolism” was dropped from medical references by the World Health Organization and replaced by “Down syndrome” during the 1970s.3 The cause of DS remained unknown until the 1950s when it became possible to identify chromosomal abnormalities with the discovery of karyotype techniques. In 1959 the French geneticist, Dr. Jerome Lejeune, reported that DS was caused by an extra 21st chromosome, an aneuploidy condition known as trisomy 21.4 The vast majority of cases of DS are due to full trisomy 21, with every somatic cell in the body having an extra 21st chromosome (Table 1). A smaller percentage of persons with DS are due to mosaic trisomy (2%e4%) and Robertsonian translocation (3%e4%).5 Reports have suggested that children with mosaic

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DS have similar health and developmental difficulties as children with full trisomy 21, but to a lesser degree6 and those with DS caused by Robertsonian translocation have increased frequency of psychiatric disorders.7 1.2. Demographics In the United States the incidence of DS at birth from 1979 to 2003 increased from 9.0 to 11.8 per 10,000 births (Table 1).8 It is suggested that the probable cause for the increase in DS is related to the trend toward later child bearing, with women over 35 being five times more likely than younger women to have children with DS.5 1.3. The intellectual and health profiles of persons with Down syndrome Although about one-third of the causes of intellectual disabilities (ID) remain unknown, the three major known causes of ID are DS, Fetal Alcohol Spectrum Disorder, and Fragile X syndrome.6 As is the case for all persons with ID, the degree of ID in persons with DS is determined by limitations in both cognitive function and in adaptive behavior (e.g., conceptual, social, and practical adaptive skills).7-9 The degree of cognitive impairment is variable, with the majority classified as mild (IQ: 50e55e69) or moderate (30e35 to 50e55) while a smaller percentage (5.9 metabolic equivalent units (METs), respectively; however, vigorous-intensity activity should be performed at least 3 days/week. Muscle- and bone-strengthening activities are important components of the recommended 60 min of daily activity and each should be performed at least 3 days/ week. Importantly, the Guidelines call for the promotion of physical activities that are age-appropriate, enjoyable, and offer variety. Recent evidence, however, suggests that most American youthdespecially adolescentsddo not meet the required amount of daily PA and that their activity levels decline as they grow.77 The issues of interest therefore are: (a) whether the PA levels of youth with DS differ from those of youth WOD, and (b) whether youth with DS meet the current recommendations for PA. Answering these questions is difficult because research on PA in youth with DS is limited. In a review of research published prior to 2008,78 the authors could not conclude whether the PA levels of youth with ID, including those of youth with DS, are different from those of children WOD. As the authors explained, this was due to methodological problems of previous research such as insufficient description of samples and questionable applicability of objective or subjective measurements of PA to youth with ID. 3.1. Measurement of PA in youth with DS Subjective PA assessments using questionnaires are not as accurate as objective ones.77 This difficulty is magnified in

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youth with DS by the need to use parental or caregiver/teacher proxy reports.78 One study demonstrated questionable accuracy of PA measurement by proxy reports for adults with ID.79 It is possible that subjective assessment of PA in youth with DS may benefit if questionnaires are obtained from both parents and teachers or caregivers; such practice may offer a more accurate representation of the activities youths with DS engage in throughout the day. Nevertheless, to our knowledge, the psychometric properties of subjective measures have not been examined in youth with DS. Finally, in-depth interviewsdtypically with parentsddo not allow for a quantification of the amount of PA performed by youth with DS. Objective PA measurements with accelerometers or pedometers are preferable, but they should be used carefully in youth with DS. Pedometers appear valid and reliable during locomotion in youth with intellectual or developmental disabilities,80,81 but their accuracy may be compromised during games and sport activities conducted in physical education.82 Additionally, spring-levered pedometers are less accurate than piezoelectric in people with DS.83 Furthermore, using step-rate cut-points to estimate moderate- and vigorousintensity activity in youth with DS may be problematic. Adults with DS have lower step-rate cut-points for activity intensity even when accounting for their shorter height compared to adults without DS84dthis may potentially apply to youth with DS. Similarly, accelerometry-determined cut-points for moderate- and vigorous-intensity activity developed for youth WOD may not be applicable to youth with DS. This has been demonstrated for adults with DS85 and it has been suggested to be partially due to an altered gait pattern that increases the energy expenditure.86 It is possible that this also applies to youth with DS who also exhibit altered gait patterns,87,88 potentially duedat least in partdto deficits of the cerebellum.89 Additionally, cut-offs developed in youth WOD may be inappropriate for those with DS because the latter have very low cardiovascular fitness. Finally, there have been some reports of compliance issues with accelerometers secured at the hip in youth with DS.90,91 Although these difficulties are not extensive, they highlight the need for adequate familiarization and parental supervision. Alternately, researchers could consider other placement sites, such as the wrist, where the accelerometer could be secured with an irremovable strap. These measurement issues should be collectively considered when evaluating previous reports of PA in youth with DS. 3.2. What are the PA levels of youth with DS? In infants with DS, movementdespecially of the legsdmay be important for motor development. Children with DS appear to reach stages in motor development with some delay.92 A notable example is the onset of independent walking which occurs about a year later (wage 2) in children with DS than children with typical development.93,94 It is possible that low levels of motor activity during early infancy may contribute to this phenomenon. One study found that, during the first 6 months of life, infants with DS show lower levels of general movements as measured by observation than

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infants with typical development.95 In contrast, analyzing video recordings, others reported no differences between infants with and without DS in the total amount of leg movements93 which are presumably more relevant for the development of walking. Subsequently, infants with DS were found to show more low-intensity and less high-intensity leg motor activity than infants with typical development.96,97 Furthermore, greater amount of high-intensity activity at about 1 year of age was associated with earlier walking onset in infants with DS.96,97 Finally, a randomized controlled study showed that infants with DS, who underwent home-based stepping training while supported over customized treadmills, achieved independent walking by an average of 101 days earlier than infants with DS not undertaking this intervention; the intervention was initiated once infants with DS could sit independently and it was conducted 5 days/week, 8 min/day, until the onset of independent walking.94 Taken together, these data suggest that alterations in PA patterns in infants with DS are associated with their motor development, thus supporting the need for early interventions.96 The objective data on PA levels of children and adolescents with DS are limited and provide somewhat conflicting results. Non-resting total energy expenditure measured with doublylabeled water did not differ between 5- and 11-year-old children with DS from the U.S. and peers WOD of similar age and BMI.98 In another U.S. study, the amounts of total, lowintensity, and moderateeintensity activity, as well as time spent sedentary measured with hip-accelerometry over 7 days did not differ between children with DS aged 3e10 years and similarly-aged siblings WOD;90 however, the children with DS participated in less and shorter bouts of vigorous-intensity activity than their siblings. Notably, children both with and without DS in that study exceeded the recommendations for total and vigorous-intensity aerobic activity. Similarly, Australian children and adolescents with DS met on average the recommended amounts of moderate- and vigorous-intensity activity as measured by hip-accelerometry91 and also appeared more active than U.S. youth.77 But there was large between-person variability in activity levels and 58% of the children with DS did not meet the recommended amount. In the same study, youths with DS aged 13e17 years showed lower total, moderate-, and vigorous-intensity activity than those aged 7e12 years, indicating a possible age-associated decline in PA. Recent acceleromety-derived data from the U.S. demonstrated that, on average, children and adolescents with DS did not engage in moderate-to-vigorous PA for 60 min/ day.99 Furthermore, PA was lower and sedentary behavior was higher in older youths with DS compared to younger ones. Another U.S. study using accelerometry100 showed that, prior to an intervention, youth with DS aged 8e15 years were active at moderate-to-vigorous levels for an average of about 43 min, although there was significant between-people variation in this value. Finally, cross-sectional accelerometry-determined data from England demonstrated lower amount and faster ageassociated decline of moderate-to-vigorous activity in people with DS than people with ID but without DS across the lifespan (Table 3).101

Youth with DS: Fitness and activity Table 3 Physical activity in youth with Down syndrome (DS). Characteristic

Description

Physical activity

1. Likely declines during the growing years 2. A large proportion of youth with DS does not meet the recommendation for daily aerobic activity 3. Youth with DS participate in a wide variety of culturally-relevant leisure activities

Barriers to physical activity Within the person 1. 2. 3. Environmental 1. 2. 3. 4. 5. 6.

Health problems Low fitness levels Low motor skills Lack of accessible, inclusive, and properly designed programs Transportation difficulties Negative attitudes towards people with disabilities Competing family responsibilities Parental education and income Lack of friends

Facilitators of physical activity Within the person 1. Knowledge on physical activity and health 2. Positive attitude towards exercise 3. Determination to succeed Environmental 1. Positive social and familial attitudes 2. Knowledgeable professionals 3. Structured programs that . 1) Are adapted to the needs of youth with DS 2) Provide knowledge on physical activity and health 3) Are inclusive 4) Promote social interaction and enjoyment

Some subjective datadobtained with parental reports or indepth interviewsdsupplement the literature on PA of youth with DS. Canadian children with DS aged 2e14 years were rated by their parents as less active and as spending more time indoors compared to siblings without DS,68 although all youth in this study with DS participated in organized sports at least once per week.69 Among 38 Australian youth with DS aged 11e18 years, only two engaged in PA more than 3 days/ weekda finding suggestive of low PA levels.102 In a second Australian study, less than one third of 208 youth with DS aged 5e18 years were found to be active at moderate-tovigorous intensity for 60 min/day, although most participated in sports.103 Finally, during in-depth interviews, parents of U.S. preschoolers with DS perceived their children as naturally active. In contrast, parents of elementary-school students perceived a gradual decrease in their children’s interest for PA, supporting the possibility for an age-associated decline among youth with DS.104 The existing objective and subjective data do not allow us to conclude with confidence whether youth with DS have lower PA levels than youth WOD, but this appears likely. Additionally, it is not known if youth with DS meet the required amounts of muscle- and bone-strengthening activities. Although there are no longitudinal data on the developmental course of PA in youth with DS, it is likely that PA declines with age in this population. Furthermore, a large

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proportion of children and adolescents with DS may not meet the recommended amount of daily aerobic activity. 3.3. Determinants of PA The study of the determinants of PA in youth with DS is still in its infancy. Following the approach of the International Classification of Functioning, Disability and Health,105 PA may be influenced by a child’s health status, functional profile, participation in life activities, and contextual factorsdeither within the person or in the environment. DS is associated with many health conditions, but there is great variability in the number and extent of conditions that youth with DS exhibit. In one study, medical issues were not associated with function among youth with DS.106 It is reasonable, however, to assume that acute health problems might present barriers to PA for youth with DS and that, when medical issues are efficiently overcome, PA may be facilitated. The functional profiles of youth with DS may also be related to their PA levels. Quantitative and qualitative data suggest that lower cognitive, behavioral, and motor skills may present barriers to PA of youth with DS.103,104,107,108 Some theorists also argue that people with DS may have a tendency for slower, safer, and more accurate movement patterns due to interactions between neurological, environmental, and taskassociated constraints.109 Additionally, the very low aerobic and muscular fitness of youth with DS may potentially affect their involvement in physical activities, especially of higher intensities, but this has not been directly examined (Table 3). Contextual factors within the person may also be at play. In support of this argument, the aforementioned lower participation in vigorous-intensity activities of children with DS compared to their siblings90 was collectively explained by age, sex, race, ethnicity, income, maternal education, and BMI. It is difficult, however, to determine the individual contributions of these factors to PA of the children in that study. As previously discussed, PA in youth with DS may decline with age,91,101,104 although one study did not find differences in sport participation between children and adolescents with DS.103 Furthermore, whether PA differs between sexes in youth with DS, as in youth WOD,74,77 is not known. Data from Taiwan, China showed no difference in recreational and sport participation between boys and girls with DS.108 In contrast, another study conducted in Taiwan, China demonstrated that, among youth with ID including DS, boys and those who had positive attitudes towards exercise were more likely to be regularly active after school.110 It is also very likely that the social and physical environment contributes to the PA levels of children and adolescents with DS (Table 3). This is supported by a wide variation in types of leisure participation among youth with DS around the world.68,102,103,108,110,111 Furthermore, it has been argued that inactivity among youth with DS may be a learned behavior partially resulting from exclusionary practices.112 Importantly, lack of accessible, inclusive, and appropriately-designed programs, as well as negative attitudes, transportation problems, competing family responsibilities, parental education

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and income, and lack of friends, all reportedly present barriers to PA for youth with DS.90,104,107 3.4. PA promotion Youth with DS reportedly participate in a wide range of recreational activities. Examples include walking, swimming, bowling, dancing, and team sports.68,102,103,108,110,111 The types of leisure participation among youth with DS likely vary around the world; for example, swimming appears common in Australia,102,103 ice-skating in Canada,68 and bicycling in Taiwan, China.108 Notably, walking is one of the most commonly performed activities among youth with DS,108,110,111 suggesting that their altered gait pattern87,88 may not present a barrier to PA. Supporting this proposition, children and adolescents with DS exhibit functional independence in locomotion tasks.106 Therefore, youth with DS have the potential to participate in all types of culturally-relevant physical activities. Unfortunately, very little data exist on interventions to promote PA in youth with DS. A randomized-controlled study found that youth with DS who learned to ride a bicycle increased their PA levels about 1 year after the intervention,100 suggesting that motor skill development may improve longterm PA. Furthermore, well-designed school programs allow students with ID including those with DS to meet the PA recommendations.113 It should also be considered that 12 weeks of exercise training, combined with health education, improves the attitudes towards exercise and psycho-social well being of adults with DS,114 but, to our knowledge, similar studies in youth with DS have not been conducted (Table 3). It has been recommended that PA promotion in all youth aimed at ameliorating the age-associated decline in PA, suppressing the development of pathological processes, and creating life-long PA habits.74 To achieve these goals in youth with DS, PA promotion should be multi-factorial. Welldesigned programs should take into account the physical, cognitive, and psycho-social health profiles of children with DS as well as their need for enjoyment and participation. But at the same time, the environmental contexts in which PA, exercise, and recreation occur must be appropriately designed. Parents tell us that the PA of their children with DS may be facilitated by positive familial and social attitudes, and structured programsdones that are adapted to the abilities of their children, offer youth with DS knowledge on PA and health, utilize their determination to succeed, and promote social interactions and enjoyment.104,107,111 4. Summary and future directions 4.1. Physical fitness Youth with DS have low peak aerobic capacity coupled with low peak HR, suggesting autonomic dysfunction may be a primary reason explaining low work performance in this population. Furthermore, persons with DS also have low muscular strength compared to individuals WOD. Exercise

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training utilizing endurance and/or resistance exercise appears beneficial for youth with DS. The role of overweight/obesity in youth with DS does not currently explain lower aerobic capacities in persons with DS, yet more work needs to be conducted to completely understand its role with regards to aerobic capacity and PA in this population. Studies involving multi-factorial issues (e.g., physiological, environmental, etc.) common to youth with DS are necessary to understand how to optimize quality of life in this population. 4.2. PA Cross-sectional data suggest that PA likely declines with growth in youth with DS and that a large proportion of these youths do not meet the recommended amount of daily aerobic activity. Effective PA promotion should be multi-factorialdit should be adapted to the physiological, cognitive, and psychosocial profiles of youth with DS, but should also consider environmental modifications. There is a need to improve the assessment of PA with objective and subjective approaches. Furthermore, longitudinal research is needed to examine how PA levels change and what factors contribute to them during growth in youth with DS. Finally, it is also important to examine the effectiveness of specific interventions aimed at increasing PA. References 1. Down JLH. Observations on an ethnic classification of idiots. London hospital reports 1866;3:259e62. 2. Bhopal R. The beautiful skull and blumenbach’s errors: the birth of the scientific concept of race. BMJ 2007;335:1308e9. 3. Classification and nomenclature of morphological defects. Lancet 1975;305:513. 4. Lejeune J, Gautier M, Turpin R. Study of somatic chromosomes from 9 mongoloid children. C R Hebd Seances Acad Sci 1959;248:1721e2. 5. Shin M, Besser LM, Kucik JE, Lu C, Siffel C, Correa A, et al. Prevalence of Down syndrome among children and adolescents in 10 regions of the United States. Pediatrics 2009;124:1565e71. 6. Schalock RL, Borthwick-Duffy SA, Buntinx WHE, Coulter DL, Craig EM. Intellectual disability: definition, classification, and systems of supports. 11th ed. Washington, DC: American Association on Intellectual & Develomental Disabilities; 2010. 7. Edwards WLR. Mental retardation: definition, classification, and systems of support. Washington, DC: American Association on Mental Retardation; 2002. 8. American Academy of Pediatrics. Health supervision for children with Down syndrome. Pediatrics 2001;107:442e9. 9. Cohen W. Health care guidelines for individuals with Down syndrome. Down Syndrome Q 1996;1:1e10. 10. So SA, Urbano RC, Hodapp RM. Hospitalizations of infants and young children with Down syndrome: evidence from inpatient person-records from a statewide administrative database. J Intellect Disabil Res 2007;51:1030e8. 11. Boulet SL, Molinari NA, Grosse SD, Honein MA, CorreaVillasenor A. Health care expenditures for infants and young children with Down syndrome in a privately insured population. J Pediatr 2008;153:241e6. 12. Geelhoed EA, Bebbington A, Bower C, Deshpande A, Leonard H. Direct health care costs of children and adolescents with Down syndrome. J Pediatr 2011;159:541e5.

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