Diobel M. Castner

Patterns of habitual physical activity in youth with and without Prader-Willi Syndrome.

Children classified as overweight or obese and those with disabilities are at a greater risk of not meeting the minimum recommendation of 60 min a day of moderate to vigorous physical activity (PA). Youth with Prader-Willi Syndrome (PWS) appear to participate in less PA compared to nonsyndromal children, likely due to syndrome-related factors. However, description of PA patterns in youth with PWS is lacking. The purpose of this study was to characterize PA in youth with PWS and to compare it to PA in children with nonsyndromal obesity. Twenty-four youth with PWS (ages 8-16 years) and 40 obese children without PWS (OB) (ages 8-11 years) wore accelerometers for eight consecutive days. Data were screened for compliance and classified into PA intensities: sedentary behavior (SED), light (LPA), moderate (MPA), vigorous (VPA) and moderate plus vigorous (MVPA). Youth with PWS spent 19.4% less time in weekly LPA (p=0.007) and 29.8% less time in weekly VPA compared to OB controls (p=0.036). All other intensities were similar between groups. In addition, PWS participated in less LPA and VPA during the weekends compared to OB, and less LPA on weekdays when compared to OB. There was also a trend towards PWS participating in less MVPA during the weekends and less VPA during the weekends than OB controls. There was a trend towards PWS participating in less VPA on weekends compared to weekdays, while OB participated similarly in VPA on weekdays and weekend days. On average, neither PWS nor OB children met minimum MVPA recommendations. The results suggest there is a need to design exercise programs for PWS youth that focus on integrating vigorous intensity activities, especially during the weekends when structured PA may not be available.

Hormonal and Metabolic Responses to Endurance Exercise in Children With Prader–Willi Syndrome and Non-Syndromic Obesity

OBJECTIVE Excess adiposity affects endocrine and metabolic function at rest and during exercise. This study evaluated the endocrine and metabolic responses to exercise in syndromic (Prader-Willi syndrome) and non-syndromic pediatric obesity. MATERIALS/METHODS Eleven PWS (10.9±1.6 y, 45.4±9.5% body fat), 12 lean (9.4±1.2 y, 17.5±4.6% body fat), and 12 obese (9.2±1.2 y, 39.9±6.8% body fat) children completed ten two-minute cycling exercise bouts, separated by one-minute rest. Blood samples were obtained at rest pre-exercise (PRE), immediately post-exercise (IP), and 15, 30 and 60 minutes into recovery. Samples were analyzed for hormones and metabolites. RESULTS Growth hormone increased in response to exercise in lean and obese but not PWS (IP>PRE; IP: lean>obese). Epinephrine increased with exercise in lean (IP>PRE), while norepinephrine increased in lean and obese (IP>PRE) but not PWS; no differences were observed between lean and obese groups at IP. No other significant hormonal group interactions existed. Glucose, lactate, free fatty acid, glycerol and ketone responses were similar among groups. CONCLUSION PWS children exhibited altered stress hormone responses to exercise. However, glucose-regulating hormones and metabolic responses to exercise appeared normal.

Effects of Adiposity and Prader-Willi Syndrome on Postexercise Heart Rate Recovery

Heart rate recovery (HRR) is an indicator of all-cause mortality in children and adults. We aimed to determine the effect of adiposity and Prader-Willi Syndrome (PWS), a congenital form of obesity, on HRR. Sixteen children of normal weight (NW = body fat % ≤85th percentile, 9.4 ± 1.1 y), 18 children with obesity (OB = body fat % >95th percentile, 9.3 ± 1.1 y), and 11 PWS youth (regardless of body fat %; 11.4 ± 2.5 y) completed peak and submaximal bike tests on separate visits. HRR was recorded one minute following peak and submaximal exercises. All groups displayed similar HRR from peak exercise, while NW (54 ± 16 beats) and OB (50 ± 12 beats) exhibited a significantly faster HRR from submaximal exercise than PWS (37 ± 14 beats). These data suggest that excess adiposity does not influence HRR in children, but other factors such as low cardiovascular fitness and/or autonomic dysfunction might be more influential.

Hormonal and metabolic responses to a resistance exercise protocol in lean children, obese children and lean adults.

During childhood, varying exercise modalities are recommended to stimulate normal growth, development, and health. This project investigated hormonal and metabolic responses triggered by a resistance exercise protocol in lean children (age: 9.3 ± 1.4 y, body fat: 18.3 ± 4.9%), obese children (age: 9.6 ± 1.3 y, body fat: 40.3 ± 5.2%) and lean adults (age: 23.3 ± 2.4 y, body fat: 12.7 ± 2.9%). The protocol consisted of stepping onto a raised platform (height = 20% of stature) while wearing a weighted vest (resistance = 50% of lean body mass). Participants completed 6 sets of 10 repetitions per leg with a 1-min rest period between sets. Blood samples were obtained at rest preexercise, immediately postexercise and 2 times throughout the 1-hr recovery to analyze possible changes in hormones and metabolites. Children-adult differences included a larger exercise-induced norepinephrine increase in adults vs. children and a decrease in glucagon in children but not adults. Similarities between adults and children were observed for GH-IGF-1 axis responses. Metabolically, children presented with lower glycolytic and increased fat metabolism after exercise than adults did. Obesity in childhood negatively influenced GH, insulin, and glucose concentrations. While adults occasionally differed from children, amount of activated lean mass, not maturation, likely drove these dissimilarities.

Hormonal and Metabolic Responses to a Single Bout of Resistance Exercise in Prader-Willi Syndrome

Background: Prader-Willi syndrome (PWS) is characterized by excessive adiposity. Excess adiposity negatively affects hormonal and metabolic responses to aerobic exercise. This study determined whether PWS and/or adiposity affected hormonal and metabolic responses to resistance exercise. Methods: Eleven children with PWS (11.4 ± 3.1 years, 43.9 ± 7.5% body fat), 12 lean children (9.3 ± 1.4 years, 18.3 ± 4.9% body fat), and 13 obese children (9.6 ± 1.3 years, 40.3 ± 5.2% body fat) participated. The children stepped onto an elevated platform while wearing a weighted vest for 6 sets of 10 repetitions per leg (sets separated by 1 min of rest). For the children with PWS, the platform height was 23.0 cm and vest load was computed as (20% of stature × 50% of lean body mass)/23.0 cm. For the controls, the platform height was 20% of the stature and vest load 50% of the lean body mass. Blood samples were obtained before, immediately after, and during recovery from exercise (+15, +30, and +60 min). Results: All groups had similar catecholamine, insulin, and glucagon responses. The groups showed no major differences in glucose and lactate levels. The PWS children demonstrated earlier increases in fatty acids during recovery and higher glycerol and ketone levels than the controls. Conclusion: The PWS children demonstrated largely intact hormonal, glycolytic, and lipolytic responses to lower-body resistance exercise. In PWS, elevated ketone levels suggest an incomplete fat oxidation.


Nutritional intakes in children with Prader - Willi syndrome and non-congenital obesity

Background Individuals with Prader–Willi syndrome (PWS) have extremely regulated diets to prevent the development of morbid obesity. Objective This study evaluated potential deficiencies in macro and micronutrients in a cohort of youth with PWS and compared them to a group of children with non-congenital obesity and to US national recommendations. Design Participants were 32 youth with PWS (age=10.8±2.6 years, body fat=46.7±10.1%) and 48 children without PWS but classified as obese (age=9.7±1.2 years, body fat=43.4±5.7%). Participants’ parents completed a training session on food recording before completing a 3-day food record during a typical week including a weekend day and two weekdays, as well as a screening form indicating nutritional supplements use. Results Youth with PWS reported less calories (1,312±75 vs. 1,531±61 kcal, p=0.03), carbohydrate (175±10 vs. 203±8 g), and sugars (67±5 vs. 81±4 g; p=0.04 for both) than obese. Youth with PWS consumed more vegetables (1.1±0.1 vs. 0.6±0.1 cups) and more of them met the daily recommendation (p<0.01 for both). Likewise, youth with PWS consumed more calcium than obese (899±53 vs. 752±43 mg) and more of them met the recommended daily dose (p=0.04 for both). The majority of participants in this study did not meet the vitamin D recommendation. Conclusion Despite consuming less calories, youth with PWS had a similar proportion of macronutrients in their diet as children with obesity. Micronutrient deficiencies in calcium and vitamin D in youth with PWS were noted despite a third of youth with PWS consuming multivitamin supplements. Special attention must be paid to the diets of youth with PWS and with obesity to ensure they are meeting micronutrient needs during this period of growth and development.

Association between physical activity and bone in children with Prader-Willi syndrome.

Abstract Background: The aim of the study was to determine if physical activity (PA) is associated with bone health in children with Prader-Willi syndrome (PWS). Methods: Participants included 23 children with PWS (age: 11.0±2.0 years). PA, measured by accelerometry, was categorized into light, moderate, vigorous and moderate plus vigorous intensities. Hip, total body minus the head (body), bone mineral content (BMC), bone mineral density (BMD) and BMD z-score (BMDz) were measured by dual X-ray absorptiometry. Separate hierarchical regression models were completed for all bone parameters, PA intensity and select covariates. Results: Moderate PA and select covariates explained the most variance in hip BMC (84.0%), BMD (61.3%) and BMDz (34.9%; p<0.05 for all). Likewise, for each body parameter, moderate PA and select covariates explained the most variance in body BMC (75.8%), BMD (74.4%) and BMDz (31.8%; p<0.05 for all). Conclusions: PA of at least moderate intensity appears important for BMC and BMD in children with PWS.

An evaluation of the implementation of a parent-led, games-based physical activity intervention: the Active Play at Home quasi-randomized trial

Trial Registration NCT02058342. Registered 6 February 2014 retrospectively registered.

Obesity and Prader-Willi Syndrome Affect Heart Rate Recovery from Dynamic Resistance Exercise in Youth

Following exercise, heart rate decline is initially driven by parasympathetic reactivation and later by sympathetic withdrawal. Obesity delays endurance exercise heart rate recovery (HRR) in both children and adults. Young people with Prader-Willi Syndrome (PWS), a congenital cause for obesity, have shown a slower 60-s endurance exercise HRR compared to lean and obese children, suggesting compromised regulation. This study further evaluated effects of obesity and PWS on resistance exercise HRR at 30 and 60 s in children. PWS (8–18 years) and lean and obese controls (8–11 years) completed a weighted step-up protocol (six sets x 10 reps per leg, separated by one-minute rest), standardized using participant stature and lean body mass. HRR was evaluated by calculated HRR value (HRRV = difference between HR at test termination and 30 (HRRV30) and 60 (HRRV60) s post-exercise). PWS and obese had a smaller HRRV30 than lean (p < 0.01 for both). Additionally, PWS had a smaller HRRV60 than lean and obese (p = 0.01 for both). Obesity appears to delay early parasympathetic reactivation, which occurs within 30 s following resistance exercise. However, the continued HRR delay at 60 s in PWS may be explained by either blunted parasympathetic nervous system reactivation, delayed sympathetic withdrawal and/or poor cardiovascular fitness.