Impact of obesity and Down syndrome on peak heart rate and aerobic capacity in youth and adults

Measurement protocols and determinants of peak oxygen consumption in adults with Down syndrome: a systematic review

This systematic review aimed to provide an overview of test protocols used to measure peak oxygen uptake (VO2peak) in adults with Down syndrome (DS) and to determine how generalisable the outcomes are for the entire population of adults with DS by describing the sample characteristics of these studies and their impact on VO2peak. A literature search (PROSPERO CRD42022309560) was performed (18 July 2023) using the following databases: PubMed, CINAHL, APA PsycINFO, Web of Science, Embase and SPORTDiscus. For articles to be included, they had to be peer-reviewed pubications, reporting VO2peak or VO2max for individuals with DS separately, with a sample of n ≥ 5 and a mean age ≥18 years. Systematic reviews and meta-analyses were excluded but their reference lists were searched for additional papers to include. Studies were evaluated for risk of bias following the guidelines of Kmet et al. The results were summarised with frequency statistics. Forty-three studies were included in this systematic review. Sample sizes of included adults with DS ranged from n = 4-226, with a total of n = 1498 adults with DS being included. Most studies (29/43) used the same standardised maximal exercise treadmill protocol to measure VO2peak in adults with DS, and 33 out of 43 studies used at least one objective criterion to determine a valid maximal effort. Participants were predominantly male, under 40 years old, and overweight or obese. Additionally, the diversity of study samples was lacking or not reported. The most widely used, standardised, maximal exercise test treadmill protocol is recommended for future use in research and practice, including objective criteria to determine valid maximal effort. The current study samples are not representative of the population of adults with DS in terms of sex, age and diverse backgrounds and therefore likely overestimate VO2peak of this population.

Assisted Cycle Therapy (ACT) Improved Self-Efficacy and Exercise Perception in Middle-Age Adults with Down Syndrome

Alzheimer's disease is prevalent in persons with Down syndrome (DS) as early as their 30s and presents as decreased social interaction, coordination, and physical activity. Therefore, changing attitudes and beliefs about exercise is key to increasing motivation for physical activity especially in middle-age adults with DS. The aim of this study was to examine the effects of Assisted Cycle Therapy (ACT) on self-efficacy and exercise perception in middle-age adults with Down syndrome (DS) following an exercise intervention three times a week for 8 weeks. Twelve participants were in the ACT group in which a motor assisted their cycling to be performed at least 30% faster than voluntary cycling (VC), 10 participants were in the voluntary cycling group, and two participants were in the no cycling (NC) group. The results showed that both exercise groups (i.e., ACT and VC) improved in their self-efficacy after the 8-week intervention. In addition, exercise perception improved following ACT, but not VC or NC. Our results are discussed with respect to their future implications for exercise in the DS population. The results can be attributed to differences in effort required by each intervention group as well as the neurotrophic factors that occur when muscle contractions create synaptic connections resulting in improvement in cognition and feelings of satisfaction.

The association between cardiovascular health and cognition in adults with Down syndrome

INTRODUCTION

Evidence in the general population suggests that predictors of cardiovascular health such as moderate to vigorous physical activity (MVPA), cardiorespiratory fitness, and systolic blood pressure are associated with cognitive function. Studies supporting these associations in adults with Down syndrome (DS) are limited. The purpose of this study was to examine the associations between systolic blood pressure, cardiorespiratory fitness, and MVPA on cognition in adults with DS.

METHODS

This is a cross-sectional analysis using baseline data from a trial in adults with DS. Participants attended a laboratory visit where resting blood pressure, cardiorespiratory fitness (VO2 Peak), and cognitive function (CANTAB® DS Battery) were obtained. The cognitive battery included tests measuring multitasking, episodic memory, and reaction time. Physical activity (accelerometer) was collected over the week following the laboratory visit. Pearson correlations and linear regressions were used to measure the impact of systolic blood pressure, cardiorespiratory fitness, and MVPA on cognitive outcomes.

RESULTS

Complete data was available for 72 adults with DS (26.8 ± 9.3 years of age, 57% female). At baseline, VO2 Peak (21.1 ± 4.2 ml/kg/min) and MVPA were low (14.4 ± 14.4 min/day), and systolic blood pressure was 118.3 ± 13.3 mmHg. VO2 Peak was correlated with simple movement time (rho =  - 0.28, p = 0.03) but was not significant using a linear regression controlling for age and sex. Systolic blood pressure was significantly associated with episodic memory (first attempt memory score: β =  - 0.11, p = 0.002; total errors: β = 0.58, p = 0.001) and reaction time (five-choice movement time: β = 4.11, p = 0.03; simple movement time: β = 6.14, p = 0.005) using age- and sex-adjusted linear regressions. No associations were observed between MVPA and multitasking, episodic memory, or reaction time.

CONCLUSION

Predictors of cardiovascular health, including cardiorespiratory fitness and systolic blood pressure, were associated with some aspects of cognition in adults with DS. While future research should examine the role of improved cardiovascular health on delaying decreases in cognitive function and dementia in adults with DS, we recommend that health care providers convey the importance of exercise and cardiovascular health to their patients with DS.

TRIAL REGISTRATION

NCT04048759, registered on August 7, 2019.

The association of increased body mass index on cardiorespiratory fitness, physical activity, and cognition in adults with down syndrome

BACKGROUND

Obesity is a significant risk factor for Alzheimer's disease; however, this association has not been explored in adults with Down syndrome.

OBJECTIVE

To examine the association of obesity, assessed by body mass index (BMI), with factors related to Alzheimer's disease risk including cardiorespiratory fitness, physical activity, and cognition in adults with Down syndrome.

METHODS

Adults with Down syndrome attended a laboratory visit where BMI, cardiorespiratory fitness (VO2 peak), and cognitive function (CANTAB® DS Battery) were obtained. Physical activity (accelerometer) was collected over the week following the laboratory visit. Wilcoxon rank sum tests were used to evaluate differences in cardiorespiratory fitness, sedentary time, moderate-to-vigorous physical activity (MVPA), and cognition between adults with obesity (BMI≥ 30 kg/m2) and those with healthy weight or overweight (BMI <30 kg/m2). Spearman correlations and linear regressions were used to measure the impact of BMI on cardiorespiratory fitness, MVPA, sedentary time, and cognition.

RESULTS

Data was collected for 79 adults with Down syndrome (26.7 ± 9.0 years of age, 54% female, 54% with obesity). VO2 peak was significantly lower in participants with obesity (18.4 ± 2.5 ml/kg/min) compared to those with healthy weight or overweight (22.9 ± 4.0 ml/kg/min, p < 0.001). BMI was negatively associated with cardiorespiratory fitness (rho = -0.614, p < 0.001). No associations were observed between BMI and physical activity or cognition.

CONCLUSIONS

Lower BMI was associated with improved cardiorespiratory fitness. However, no associations were observed between BMI and cognition or physical activity.

NCT REGISTRATION

NCT04048759.

Comprehensive cardiopulmonary profile of individuals with Down syndrome

BACKGROUND

Individuals with Down syndrome (DS) have low levels of cardiorespiratory fitness and previous studies have shown that these low levels of fitness have a physiological cause. During exercise, the cardiovascular, ventilatory and muscular systems are simultaneously active. While individual parameters of these systems have been investigated in DS before, the interaction between these parameters and systems have not been discussed in detail. Doing so may provide important insight regarding the aetiology of low cardiorespiratory fitness and which parameters of the cardiovascular, pulmonary and muscular systems are altered in individuals with DS compared with their peers without DS.

METHODS

Cardiopulmonary exercise tests were performed in healthy adults with and without DS. Parameters related to the cardiovascular, ventilatory and muscular systems were collected until VO_2peak . In total, 51 participants were included in analysis, of which 21 had DS.

RESULTS

Individuals with DS showed lower peak values for all collected outcomes (P ≤ 0.001) compared with those without DS, except for ventilatory threshold as a percentage of maximal oxygen uptake and V_E /VCO₂ slope, which were similar.

CONCLUSIONS

Our results show that individuals with DS present impairments across the cardiovascular, ventilatory and muscular aspects of the cardiopulmonary system.

Resistance training and Down Syndrome: A narrative review on considerations for exercise prescription and safety

The current manuscript reviews the literature on the health effects of resistance training (RT) for individuals with Down syndrome (DS), focusing on this training modality’s methodology, application, and safety. The literature has mentioned that early aging in this population is associated with loss of muscle strength, lower lean and bone mass, and increased obesity. It is necessary to propose non-pharmacological measures for prevention and health promotion. Thus, this review suggests a current research-based RT guide for individuals with DS. This review is divided into three sections: Section 2 briefly reviews DS and the effects on structural and functional decline and how exercise and physical activity can influence health aspects in this population; Section 3 summarizes the evidence for RT prescription; Section 4 briefly reviews the health and potential benefits of RT in individuals with DS. The findings from this review suggest that most individuals with DS should engage in moderate-intensity RT at least 2 days a week and perform RT on the major muscle groups and include balance training. The RT program should be modified and adapted according to individuals’ characteristics and limitations. RT promotes positive, health-related benefits such as increasing strength, improving body composition, improving functional capacity and balance, reducing inflammatory status and oxidative stress, and improving the immune system. The RT protocols summarized in this current review provide guidance, critical conclusions, and novel research settings, which could be useful to coaches, clinicians, and researchers to effectively design RT program for individuals with DS.

Effectiveness of Swimming Program in Adolescents with Down Syndrome

The aim of this study was to estimate the influence of a 33-week swimming program on aerobic capacity, muscle strength, balance, flexibility, and body composition of adolescents with Down syndrome (DS). Twenty-two adolescents diagnosed with DS were randomly allocated into the training group (T) and the control group (C). The T group participated in 33 weeks of water-based exercise and a swimming program while the control group maintained their normal daily activity. Following thirty-three weeks of swimming program, body mass, body fat, and BMI of the T group decreased significantly (from 56.8 ± 7.97 kg to 55.0 ± 7.11 kg, from 15.1 ± 4.47 kg to 13.2 ± 3.92 kg, and from 25.1 ± 2.37 to 24.0 ± 2.05, respectively) while a significant increase was recorded in C (from 57.3 ± 8.43 kg to 59.7 ± 8.29 kg, from 14.5 ± 2.76 kg to 16.0 ± 3.11 kg, and from 25.4 ± 2.46 to 26.0 ± 2.72, respectively). Moreover, significant improvement in aerobic capacity in the T group was noted; VO₂max (mL/kg/min) increased by 16.3% in T and decreased by 4.8% in C. Improvement in static arm strength, trunk strength and endurance/functional strength were noted in T, while the parameters did not change in C. The speed of arm movement, balance and flexibility did not change following the intervention. Also, the aquatic skills improved significantly in the training group. Changes in C were not significant. The results of our study indicate that 33-week swimming program significantly improved health status and swimming skills in adolescents with DS.

Anthropometry does not fully explain low fitness among adults with Down syndrome

BACKGROUND

Cardiorespiratory fitness, expressed as peak oxygen uptake during exercise (VO₂ peak), is an important predictor of cardiovascular health and is related to anthropometry in the general population. Individuals with Down syndrome (DS) have reduced cardiorespiratory fitness and often exhibit different anthropometrics compared with the general population. Interestingly, the relation between anthropometry and cardiorespiratory fitness found in the general population is not apparent in individuals with DS. However, accurate measures with dual energy X-ray absorptiometry (DEXA) scan have not been used to investigate this relationship in this population. The purpose of this paper was to investigate the relationship between accurate measures of anthropometry and cardiorespiratory fitness in adults with DS compared with an age-matched and sex-matched control group.

METHODS

Anthropometrics (height, weight, waist and hip circumference, body composition via DEXA) and cardiorespiratory fitness (VO₂ peak, measured during a graded maximal exercise test) were assessed in adults with (n = 9; 25 ± 3 years; 6 male patients) and without DS (n = 10, 24 ± 4 years; 5 male patients).

RESULTS

Participants with DS were shorter (P < 0.01) than without DS and had a higher body mass index (P < 0.01), waist circumference (WC) (P = 0.026) and waist/height ratio (WHtR) (P < 0.01), but similar weight, body surface area (BSA), waist/hip ratio and body composition (P > 0.05). Participants with DS had significantly lower relative VO₂ peak and VO₂ peak corrected for total lean mass (TLM), but similar absolute VO₂ peak, compared with without DS. In participants with DS, only WC and WHtR were associated with VO₂ peak, whereas in participants without DS, height, weight, BSA, TLM, leg lean mass and body fat percentage were associated with VO₂ peak.

CONCLUSIONS

These results suggest that the relation between anthropometry and cardiorespiratory fitness found in the general population is not the same in adults with DS and that anthropometrics do not fully explain cardiorespiratory fitness in adults with DS. Further research into potential alternative explanations is required.

Age-Group Differences in Body Mass Index, Weight, and Height in Adults With Down Syndrome and Adults With Intellectual Disability From the United States

The authors examined if body mass index (BMI), weight, and height across age groups differ between adults with Down syndrome (DS) and adults with intellectual disability but without DS. They conducted secondary analyses of cross-sectional data from 45,803 individuals from the United States from 2009 to 2014 of the National Core Indicators Adult Consumer Survey across five age groups: 18-29, 30-39, 40-49, 50-59, and 60+ years. For both men and women with DS, BMI and weight increased between the 18- to 29- and the 30- to 39-year age groups and decreased thereafter. For both men and women with intellectual disability, BMI and weight increased between the 18- to 29- and the 30- to 39-year age groups, stayed about the same until the 50- to 59-year age group, and decreased thereafter. Height demonstrated a small but significant decrease with older age in all groups. These cross-sectional comparisons indicate that BMI and weight may start decreasing at a younger age in adults with DS than in adults with intellectual disability.

Bidirectional longitudinal associations of fatness with physical fitness in adolescents with Down syndrome. The UP&DOWN Longitudinal study

BACKGROUND

The aim of this study was to examine the bidirectional longitudinal associations of several markers of fatness and physical fitness in adolescents with Down syndrome.

METHODS

This study comprised a total of 111 adolescents (41 females), aged from 11 to 20 years with complete data at the baseline. We had a drop-out of <10% from the baseline to the 2-year follow-up. The ALPHA health-related fitness test battery for youth was used.

RESULTS

Our results show that all fatness variables at the baseline were associated with a 2-year change in cardiorespiratory fitness (β ranging from -0.32 to -0.38; all p < .05), but not with muscular and motor fitness (p > .05). However, no associations were found between physical fitness components as predictors and fatness indicators (p > .05).

CONCLUSIONS

Results suggest that reducing fatness during adolescence might represent a modifiable factor to improve cardiorespiratory fitness at the 2-year follow-up, but not vice versa since associations were not bidirectional.

Predictors of perceived health in adults with an intellectual disability

BACKGROUND

The effects of Intellectual disability (ID) levels, body mass index (BMI) categories, and other factors on perceived health status of adults with ID are not well-known.

AIMS

We aimed to examine: (a) the relationship between perceived health and level of intellectual function; (b) the influence of different BMI categories on a perceived health; and (c) the effect of the modifiable behavioral factors on perceived health.

METHODS AND PROCEDURES

We examined the aims using data from the 2013-2014 Adult Consumer Survey of the National Core Indicator. We extracted demographic (e.g. age, BMI) and modifiable behavior-related variables (e.g. physical activity participation, having a job) and used logistic regression models to analyze the relationships.

OUTCOMES AND RESULTS

Logistic regressions showed that more severe ID level is associated with worse perceived health, but when other variables related to personal and behavioral characteristics were accounted for, this relationship was no longer significant. Obese adults with ID had worse perceived health than those with normal weight; this effect remained significant even after considering other variables. Those in the overweight category did not differ in perceived health status from those of normal weight. The effects of all modifiable behaviors on perceived health were significant.

CONCLUSIONS AND IMPLICATIONS

Health promotion programs for adults with ID may benefit by consideration of modifiable behaviors.

The health benefits of exercise therapy for patients with Down syndrome: A systematic review

Background

Many patients with Down syndrome (PWDS) have poor cardiometabolic risk profiles, aerobic capacities and weak hypotonic muscles, primarily because of physical inactivity and poor diet.

Objectives

This study discusses the benefits of exercise therapy on body composition, aerobic capacity, muscle strength, proprioception and cardiometabolic profiles of PWDS.

Methods

A literature review using the Crossref metadatabase, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), focusing on the period 2007-2018, was undertaken. Each record was judged adopting the modified Downs and Black Appraisal Scale. The literature investigation identified 15 701 records. Records were excluded if they were published before 2007, pertained to the impact of exercise on intellectual disabilities beyond Down syndrome or the impact of medical, pharmaceutical, nutrition and psychological interventions among PWDS and were published in languages besides English. Nineteen articles were synthesised into this commentary.

Results

PWDS have a heightened cardiometabolic risk profile and high oxidative stress associated with elevated insulin resistance, poor insulin sensitivity, atherosclerosis and hypertension. PWDS have low aerobic capacity (VO_2max), peak heart rates, muscle strength, agility and balance. Regular physical activity is beneficial to improve their VO_2max and muscle strength. Moreover, regular physical activity reduces lipid peroxidation and arterial cell wall damage, the pathogenesis of atheroma is limited.

Conclusion

Exercise therapy compliance seems to have a positive impact on the cardiometabolic risk profile, muscle strength and aerobic work capacity of PWDS. Nonetheless, additional vigorous experimental investigations are necessary to better understand the effect of exercise therapy on the aerobic, strength, proprioception and cardiometabolic risk profile of PWDS.

Peripheral blood flow regulation in response to sympathetic stimulation in individuals with Down syndrome

Background

Individuals with Down syndrome (DS) experience autonomic dysfunction, with reduced sympathetic and parasympathetic control. This results in alterations in resting heart rate and blood pressure and attenuated responses to sympathoexcitatory stimuli. It is unknown to what extent this impacts the regulation of peripheral blood flow in response to sympathetic stimuli, which is an important prerequisite to exercise and perform work. Therefore, we aimed to investigate differences in peripheral blood flow regulation in response to lower body negative pressure (LBNP) between individuals with and without DS.

Methods

Participants (n=10 males with DS and n=11 male controls, mean age 23.7 years ± 3.2) underwent 5 min of LBNP stimulations (-20 mmHg), after resting supine for 10 min. One minute steady state blood pressure and blood flow at baseline and during LBNP were obtained for analysis. Mean flow velocity and arterial diameters were recorded with ultrasonography; foreram blood flow (FBF), shear rate and forearm vascular conductance (FVC) were calculated using brachial blood pressure measured right before ultrasound recordings.

Results

Participants with DS responded differently (consistent with reduced vasoconstrictive control) to the LBNP stimulus (significant ConditionxGroup interaction effect) for mean velocity (p=0.02), FBF (p=0.04), shear rate (p=0.02) and FVC (p=0.03), compared to participants without DS.

Conclusion

Young males with DS exhibit reduced peripheral regulation of blood flow in response to LBNP compared to controls, indicating a blunted sympathetic control of blood flow. Further research is necessary to explore the impact of these findings on exercise and work capacity.

An exploratory study of the association between physical activity, cardiovascular fitness and body size in children with Down syndrome

OBJECTIVE

To explore the association between physical activity, cardiovascular fitness and body size among children with Down syndrome.

METHOD

Physical activity, cardiovascular fitness and body size were measured by accelerometry, maximal fitness test and anthropometric measurements (BMI, waist circumference), respectively.

RESULTS

Fourteen children with Down syndrome (8 boys, 6 girls; mean age 12.9 years) participated. There was no significant correlation between physical activity and cardiovascular fitness or physical activity and body size. Children with Down syndrome who were fitter, had lower BMIs (r = -0.77, 95% confidence interval (CI) -0.41 to -0.93) and smaller waist circumference (r = -0.75, 95% CI -0.36 to -0.92).

CONCLUSION

Preliminary evidence suggests physical activity may not be associated with either body size or fitness in children with Down syndrome. Body size appears to be inversely related to fitness in children with Down syndrome.

Accuracy of the prediction equation for the determination of maximum heart rate in adults with Down syndrome

BACKGROUND

The purpose of the study was to determine if the regression formula developed for the prediction of maximum heart rate (HR) is valid for adults with Down syndrome (DS).

METHODS

Thirty-six adults with DS (31.7 ± 6.8 years; 20 men, 16 women) completed a maximal aerobic test. Maximum HR and VO₂ peak were measured directly on a motorised treadmill with a metabolic analyser. Predicted HR was estimated with the regression equation developed for individuals with DS (Fernhall et al. 2001). Differences between measured versus predicted maximum HR were assessed with a dependent T-test and the relationship with Pearson correlational analyses. Agreement was assessed with Bland-Altman analysis.

RESULTS

There was a significant difference between directly measured maximum HR and predicted maximum HR (P < 0.01). There was no significant relationship between these variables. Bland-Altman analysis indicated that there was measurement bias (+4.7) and large limits of agreement (+26.7 and -17.4) between measured and predicted maximum HR. The Bland-Altman plot also demonstrated the presence of heteroscedasticity.

CONCLUSIONS

The results indicate that the regression formula developed for individuals with DS was not accurate in this sample of DS adults aged 19 to 46 years. Future studies should develop different prediction equations for more specific age and body mass index categories for individuals with DS.

Overweight and obesity in children and adolescents with Down syndrome-prevalence, determinants, consequences, and interventions: A literature review

BACKGROUND

Children with Down syndrome (DS) are more likely to be overweight or obese than the general population of youth without DS.

AIMS

To review the prevalence of overweight and obesity and their determinants in youth with DS. The health consequences and the effectiveness of interventions were also examined.

METHODS AND PROCEDURES

A search using MEDLINE, Embase, Web of Science, Scopus, CINAHL, PsycINFO, SPORTDiscus, LILACS, and COCHRANE was conducted. From a total of 4280 studies, we included 45 original research articles published between 1988 and 2015.

OUTCOMES AND RESULTS

The combined prevalence of overweight and obesity varied between studies from 23% to 70%. Youth with DS had higher rates of overweight and obesity than youths without DS. Likely determinants of obesity included increased leptin, decreased resting energy expenditure, comorbidities, unfavorable diet, and low physical activity levels. Obesity was positively associated with obstructive sleep apnea, dyslipidemia, hyperinsulinemia, and gait disorder. Interventions for obesity prevention and control were primarily based on exercise-based programs, and were insufficient to achieve weight or fat loss.

CONCLUSIONS AND IMPLICATIONS

Population-based research is needed to identify risk factors and support multi-factorial strategies for reducing overweight and obesity in children and adolescents with DS.

Reliability and convergent validity of the 6-min run test in young adults with Down syndrome

BACKGROUND

There is limited evidence about the psychometric properties of field tests to measure cardiorespiratory fitness in people with Down syndrome.

OBJECTIVE

This study aimed at analyzing the reliability and convergent validity of the 6-min run test when performed by young adults with Down syndrome (DS).

METHODS

In a cross-sectional design fifty-one young adults with DS (mean age 26.20 ± 7.14 years; 54% women) performed the 6-min run test and the 16-min shuttle run test twice with a one week-interval between test and retest.

RESULTS

The 6-min run test offered high reliability for the distances covered (ICC: 0.974; 95% CI: 0.955-0.985) and good reliability when comparing peak heart rate values obtained in the test and retest (ICC: 0.870; 95% CI: 0.772-0.926). A significant correlation between the 6-min run test and the 16-min shuttle run test was observed for the test (r = 0.705; Sig = 0.001), and retest phases (r = 0.651; Sig = 0.001). The relationship between the estimated maximal oxygen consumption (VO₂ max) peak after the performance of the 16-min shuttle run test and the distance covered by the 6-min run test was statistically significant (r > 0.7). No significant differences were found between the equations that estimate VO₂ peak for both tests.

CONCLUSIONS

These findings suggest that the 6-min run test shows high test/retest reliability and moderate to moderately high convergent validity when performed by adults with DS.

The role of fatness on physical fitness in adolescents with and without Down syndrome: The UP&DOWN study

BACKGROUND/OBJECTIVES

Adolescents with Down syndrome (DS) exhibit higher levels of fatness and low levels of physical fitness compared with those without DS. In adolescents without DS, fatness is tightly associated with physical fitness, but this association is unclear in adolescents with DS. The aim of this study was to examine the association between several markers of fatness and physical fitness in a relative large sample of adolescents with and without DS.

SUBJECTS/METHODS

A total of 111 adolescents with DS (41 females) aged 11-20 years participated in this cross-sectional study. We also included a sex-matched control group (ratio 1:2) of 222 adolescents without DS aged 12-18 years, participating in the UP&DOWN Study. The Assessing Level of Physical Activity (ALPHA) health-related fitness test battery for adolescents was used to assess fatness and physical fitness.

RESULTS

Our results show that fatness is not associated with low levels of physical fitness in adolescents with DS (that is, 3 of the 16 analyses identified differences in physical fitness variables by groups of fatness). In contrast, fatness, as expected, is associated with levels of physical fitness in adolescents without DS (that is, 13 of the 16 analyses identified differences in physical fitness variables by groups of fatness).

CONCLUSIONS

The present finding contributes to new knowledge by suggesting that the role of fatness on physical fitness is different in adolescents with and without DS, and consequently, the poor levels of physical fitness in adolescents with DS may be due to the syndrome rather than the high prevalence of obesity from this population.