Strength of relationship between body mass index and gross motor capacity in youth with intellectual disabilities.

BACKGROUND: Adequate skill levels of gross motor capacity affect activities of daily living, participation in recreational activities and general physical activity levels of youths (7-21 years). Most studies of typically developing youths have reported significant negative relationships between gross motor capacity and body mass index. The latter findings are especially of concern for youths with intellectual disabilities in that it has been estimated that 61% of children and 66% of adolescents were classified as overweight/obese. Therefore, the purpose of this study was to determine the strength of the relationship between body mass index and gross motor capacity among youths with mild to moderate intellectual disability (ID). METHODS: Components of the Bruininks-Oseretsky Test of Motor Proficiency (BOT-2) were used for designated aspects of gross motor capacity: six items for upper limb coordination (ULC); seven items for balance (BAL); six items for bilateral coordination (BLC); and one item for agility (A-2). Participants consisted of 654 youths (438 men), ages 8-21 years with ID. Participants were divided into pre-puberty and post-puberty men (post ≥12 years) and women (post ≥10 years of age). Body mass index (BMI, kg/m2) was determined by height and weight measurements on the day of testing. A Kendall's tau correlation coefficient (τ) was used to determine the strength of the relationship between body mass index and gross motor capacity (BOT-2 test scores). RESULTS: The τ values for both pre-puberty and post-puberty for all BAL, BLC, A-2 tests and for three of the six ULC tests were negligible to very weak (τ = 0 to ±0.19). Higher τ values were seen for pre-puberty youths in three of the ULC tests, but they fell within the weak range (τ < 0.24). When combining all pre-puberty and post-puberty participants, τ values were in the negligible to very weak range for all tests. CONCLUSION: The strength of relationship between body mass index and gross motor capacity as measured by the BOT-2 subtest item scores used in this study is very weak and suggests that they are not clinically relevant.

Association of muscular strength with total and central adiposity in adolescents with intellectual disability.

BACKGROUND: It has been established that for youth without disabilities, muscular strength (MS) is negatively associated with total and central adiposity. However, this relationship has not been clearly established for youth with intellectual disability (ID). The purpose of this study was to examine the association of MS with total and central adiposity in adolescents with ID. METHOD: Participants were 59 adolescents (40 males and 19 females: age 16.29 ± 1.66 years) with ID. Total and central adiposity were evaluated with dual-energy x-ray absorptiometry (DXA), body mass index (BMI), BMI z-score, waist circumference (WC), and conicity index (C-index). MS was evaluated with the score on the Bruininks-Oseretsky Test of Motor Proficiency (range, 0 to 42, with higher scores indicating better performance). Sex-specific maturity offset equations were used to evaluate somatic maturity. Spearman's correlation coefficients and sequential multiple regression were used to examine associations between MS and adiposity. RESULTS: Muscular strength score was negatively associated with BMI (sr = -0.32; P < 0.05), percent body fat (%BF; total, trunk, android and gynoid regions) (sr = -0.51 to -0.58; P < 0.01), and android-to-gynoid fat ratio (sr = -0.29; P < 0.05). After control for somatic maturity and sex, regression analysis indicated that MS score explained 10%-17% of the variance in BMI, BMI z-score, %BF (total, trunk, android and gynoid regions), WC, C-index and android-to-gynoid fat ratio. CONCLUSIONS: These findings suggest that MS is associated with DXA- and anthropometric-determined total and central adiposity among adolescents with ID.

Regional distribution of blood flow of dogs during graded dynamic exercise.

The regional blood flow response to progressive treadmill exercise was measured with radioactive microspheres in 25 untrained mongrel dogs. Incremental increases in work intensity resulted in corresponding increases in blood flows to the gracilis, gastrocnemius, semimembranosus, and semitendinosus muscles of the hindlimb and to the heart. During maximal exercise, blood flow was greatest in the semimembranosus muscle and lowest in the semitendinosus muscle (342 and 134 ml-1.100 g tissue-1.min-1, respectively). Exercise produced a decrease in blood flow to the temporalis muscle, which was classified as nonlocomotive in function. Blood flows to the stomach, pancreas, and large intestine decreased at the lowest exercise work load and remained diminished throughout the continuum to maximal exercise. Blood flows to the small intestine and spleen were maintained during submaximal exercise but were reduced by 50% at maximal O2 consumption (VO2max). No changes in blood flows to the kidneys, adrenal glands, liver, and brain were found. These results demonstrate that 1) renal blood flow is maintained at resting levels during exercise in untrained dogs; 2) blood flow changes in the various organs of the splanchnic region of dogs during exercise are heterogeneous; and 3) blood flows to the working skeletal muscles of dogs progressively increase with increasing work loads up to VO2max.

Physical fitness and adults with mental retardation. An overview of current research and future directions.

The deinstitutionalization movement of the past 25 years has focused on the placement of people with mental retardation into community-based settings. There is a need for exercise- and health-related professionals to demonstrate a thorough understanding of the term mental retardation and all of the intellectual and behavioural ramifications that coexist with this condition before addressing the 'how to' of fitness evaluation. Therefore, the article outlines the range of intellectual and behavioural characteristics of this population, based on the level of retardation. Many researchers investigating body composition have reported that a disproportionate number of adults with mental retardation carry a percentage of body fat that would be considered unhealthy (e.g. it increases the risk of early onset of such diseases as hypertension and adult onset diabetes mellitus). Living arrangements (i.e. institution vs smaller residences) play a role in the prevalence of obesity. Many attempts of researchers to control weight in adults with mental retardation through caloric restriction, exercise, and a combination of diet and exercise, have had a varied outcome. Cardiovascular capacity is considered by most exercise physiologists as the major physiological indicator for overall fitness. The majority of researchers who have evaluated the cardiovascular fitness levels of adults with mental retardation have reported fitness levels representative of a very sedentary population. Therefore, one would expect a keen sense of urgency among researchers to develop training regimens targeted specifically for people with mental retardation. Many have been developed, but to date only 2 cardiovascular training regimens have been reported that specifically describe the necessary components of an exercise programme (i.e. frequency, duration, intensity) that would allow for reproducibility--a stationary bicycle routine using the Schwinn 'Air-Dyne' ergometer and a run/walk programme. Of these, only the programme using the Schwinn 'Air-Dyne' ergometer reported significant improvements in cardiopulmonary fitness. Researchers have demonstrated that: (1) body strength is valuable for recreation activities and activities of daily living; (2) competence in upper body muscular skills is a prerequisite for many available vocational opportunities; and (3) positive correlations have been established between muscular strength and industrial work performance in people with mental retardation. Therefore, there is a need for appropriate evaluation procedures for determining the muscular strength and endurance of people with mental retardation. The future directions for researchers and professionals concerned with the fitness status of people with mental retardation includes answering question such as: What will be the effect of obesity on general health status?(ABSTRACT TRUNCATED AT 400 WORDS)

Physical activity for the chronically ill and disabled.

Exercise prescription principles for persons without chronic disease and/or disability are based on well developed scientific information. While there are varied objectives for being physically active, including enhancing physical fitness, promoting health by reducing the risk for chronic disease and ensuring safety during exercise participation, the essence of the exercise prescription is based on individual interests, health needs and clinical status, and therefore the aforementioned goals do not always carry equal weight. In the same manner, the principles of exercise prescription for persons with chronic disease and/or disability should place more emphasis on the patient's clinical status and, as a result, the exercise mode, intensity, frequency and duration are usually modified according to their clinical condition. Presently, these exercise prescription principles have been scientifically defined for clients with coronary heart disease. However, other diseases and/or disabilities have been studied less (e.g. renal failure, cancer, chronic fatigue syndrome, cerebral palsy). This article reviews these issues with specific reference to persons with chronic diseases and disabilities.

Introduction: exercise capacities and adaptations of people with chronic disabilities--current research, future directions, and widespread applicability.

This symposium addresses the unique physiological problems, current research, future needs, and widespread applicability for research involving people experiencing five major chronic disabilities within the United States: quadriplegia, paraplegia, mental retardation, multiple sclerosis, and poliomyelitis. Each author represents ACSM members who, by their distinguished research efforts, exemplify scientists who have demonstrated their dedication to the specific needs of these populations. The papers will give a brief description of the pathophysiology of the disability and the resultant effects upon the group's acute response to exercise and their physiological adaptations to exercise programs. Each paper will include reports on the state of current research and what benefits to that group could be expected if a major research breakthrough occurred. Additionally, the papers will indicate the major research questions currently confronting each population and a brief statement about the strategy needed to resolve these questions. If applicable, the authors will address how such a model (of the specific disability/disease) could be used to better understand the able-bodied response to exercise. The purpose of this symposium, therefore, was not only to better understand the effects of exercise on persons having chronic disabilities, but from a physiological point of view, to use what we know about the response of people with chronic disabilities to better understand the able-bodied response.

Cardiovascular fitness as related to leg strength in adults with mental retardation.

The purpose of this study was to compare cardiovascular fitness to leg strength of young adults (mean age = 25.2 yr) with mental retardation (MR) with and without Down syndrome (DS) and to determine whether a relationship exists. Thirteen adults (9 males, 4 females) with DS and 24 adults (16 males, 8 females) with MR but without DS participated in this study. Cardiovascular capacity (VO2peak) for each subject was determined by a treadmill test (GXT) and isokinetic knee flexion and extension strength (peak torque and average power) were determined by isokinetic dynamometry. Results generally demonstrated significant positive relationships (P < 0.05) between VO2peak and isokinetic leg strength (r = 0.61), with the relationship being substantial mainly for subjects with Down syndrome (r = 0.84). The results of this study suggest that leg strength may be an important contributor to VO2peak for persons with mental retardation.

Mentally retarded individuals--a population at risk?

When comparing the aging process of mentally retarded (MR) persons with the nondisabled population, researchers have established an earlier lower limit for the onset of old age for MR persons and a higher mortality rate. The reason for early senescence has not been successfully resolved, but the finding that cardiovascular disorders are the most prevalent form of disease among elderly MR persons suggests a relationship between lifestyles and higher mortality rate. Indeed, studies that evaluated the cardiovascular fitness (CVF) of MR individuals demonstrated substandard levels of fitness. The results of these studies, however, are not conclusive due to variation in test methodologies, motivational factors, and issues of test validity and reliability. Training studies which have purported to determine trainability of this population have also shown confusing results, perhaps attributed to the same protocol inconsistencies. Therefore, the purposes of this article are 1) to review previous methods of evaluating CVF of MR adults and determine whether testing methodologies invalidate the results of these studies, 2) to review training studies involving adult MR individuals and determine whether this population is capable of improving their CVF, and 3) to identify areas where further research is needed to fully describe the functional cardiovascular characteristics of MR adults.

Effects of a minimally supervised exercise program for mentally retarded adults.

Previous exercise studies that attempted to improve the cardiovascular fitness (CVF) of mentally retarded (MR) adults were flawed with methodological shortcomings that prevented conclusive results. At issue in these training studies were fitness test validity and reliability, exactness of duration and intensity of training, and an inordinate amount of supervision. Therefore, we sought to determine whether moderately MR adults (seven males, five females; IQ = 61 +/- 3, age = 25 +/- 3 yr) could improve their CVF through a minimally supervised 16-wk training program. Each subject repeated exercise tests twice on two different modes of exercise, the treadmill (TM) and Schwinn Air-Dyne ergometer (SAE), before training to ensure validity and reliability of initial CVF levels. Intensity and frequency of exercise were closely monitored. An observer was present during the training bouts, but, following initial instructions, no additional encouragement or instructions were given. Although the training program significantly increased peak VO2 (29.2 +/- 8 to 33.5 +/- 9 ml.kg-1.min-1) and peak ventilation (73 +/- 26 to 81 +/- 231.min-1) when assessed on the TM, significant changes in these same parameters were not seen when assessed on the SAE. The importance of these results was discussed.

Research on physical activity and disability: an emerging national priority.

Despite the voluminous amount of research that has been published in the field of exercise science over the past three decades, there remains a paucity of information on the activity patterns and physiological responses to exercise in persons with disabilities. In an era when physical activity has grown to new heights in terms of its importance in promoting health and preventing disease, many questions pertaining to how it affects the lives of individuals with physical disabilities remain unanswered. The purpose of this paper is to review the prevalence of disability in the United States and to present recommendations for future research on physical activity and disability. A related objective of this paper is to encourage exercise scientists to undertake research on this increasingly significant group of American citizens.

Comparison of isokinetic peak force and work parameters in youth with and without mental retardation.

PURPOSE: The purpose of this study was to compare isokinetic knee (flexion and extension) strength of nondisabled youth (ND; 15 males, 15 females; males = 12.7 +/- 2 yr; females = 13.4 +/- 2 yr) and youths with mental retardations (MR, 17 males + 13 females; male = 14.7 +/- 2 yr; females = 13.6 +/- 2 yr). METHODS: Subjects were evaluated on a Kin-Con isokinetic dynamometer at a speed of 60 degrees x s(-1). Parameters measured were peak torque (PT), time to PT, angle of PT, total work (W), and PT hamstrings/quadriceps (HQ) ratio. Peak torque was also corrected by weight (BW) and body mass index (BMI). Peak torque, time to peak torque, angle of peak torque, and total work were analyzed using a 2 x 2 x 2 (groups x gender x muscle) repeated measures analysis of variance (MANOVA). Flexion/extension ratios, BMI, and BW were analyzed by separate 2 x 2 (group x gender) analyses of variance. RESULTS: Results of this study suggest that: 1) while gender differences are apparent in the ND population they are not evident in individuals with MR; 2) knee extension strength is higher for ND youth, thus causing lower PT HQ ratios when compared with those in youth with MR; 3) angle of PT and time to PT were similar among groups; and 4) total work performed is lower in individuals with MR. CONCLUSIONS: It was concluded that parameters of strength production in individuals with MR are not consistent and do not follow the same pattern as their nonretarded peers.

The effect of lower body positive pressure on the exercise capacity of individuals with spinal cord injury.

The purpose of this study was to determine the effect lower body positive pressure (LBPP) has on the cardiovascular/exercise capacities of individuals with spinal cord injury (SCI) during both arm crank exercise (ACE) and wheelchair exercise performed on a treadmill (WCTM). Ten male adults (age = 31.1 +/- 10 yr) with SCI and five male nondisabled (ND) adults (31.2 +/- 10 yr) participated in this study. The ND subjects performed ACE only. For subjects with SCI, significantly higher (P < 0.025) peak VO2 (1042 +/- 212 vs 839 +/- 218 ml.min-1), peak VE (46 +/- 17 vs 35 +/- 9 l.min-1), and work rate (50 +/- 15 vs 40 +/- 13 W) were seen during ACE with LBPP. No significant differences for peak VO2, VE, or work rate were seen for the ND subjects with LBPP during ACE. In addition, significantly higher peak VO2 (960 +/- 322 vs 828 +/- 312 ml.min-1) was recorded with LBPP for the subjects with SCI during WCTM. Cardiac output (Q, l.min-1; CO2 rebreathing method) was measured at 50% peak VO2 for both ND subjects and subjects with SCI during ACE. Subjects with SCI demonstrated significantly higher SV (94 +/- 20 vs 84 +/- 20 ml) with LBPP. No differences were observed in SV at 50% peak VO2 during ACE for the ND subjects with LBPP. The results of this study suggest that for individuals with SCI, LBPP augments exercise capacity by preventing the redistribution of blood to the lower extremities.

The cardiovascular capacities of adults with Down syndrome: a comparative study.

The purpose of this study was to compare the cardiovascular capacities of individuals with Down syndrome (DS) to individuals without Down syndrome who are mentally retarded. Sixteen young adults with DS and 16 individuals without DS (12 males and 4 females, respectively), all with mild/moderate mental retardation, participated in this study. Peak VO2 (absolute and relative), VE (1.min-1), heart rate (HR, b.min-1), and RER (VCO2/VO2) were determined by exercise tests utilizing a treadmill (TM) and Schwinn Air-Dyne ergometer (SAE). The best test result was chosen from the TM and SAE tests and used for statistical comparisons. Cardiac output (Q, 1.min-1) was measured while standing quietly and while walking at 3 mph, 0% grade, using the CO2 rebreathing method for 11 (9 males and 2 females) subjects from each group. Arteriovenous oxygen differences (a-v O2), cardiac index (QI), and stroke volume (SV) were calculated from VO2, Q, HR, and body surface area. Peripheral vascular resistance (PVR), left ventricular work index (LVWI), and left ventricular stroke work index (LVSWI) were calculated from mean arterial pressure, Q, QI, and stroke volume index. Results showed that individuals without DS had statistically significant (P less than 0.01) higher mean peak VO2 (35.6 vs 24.6 ml.kg-1.min-1; 2567 vs 1683 ml.min-1), VE (89.3 vs 59.2 1/min-1), and HR (179 vs 159 b.min-1) than individuals with DS, respectively. No differences in RER were seen between the groups. No differences were seen in cardiovascular parameters measured while quietly standing.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiorespiratory capacity of individuals with mental retardation including Down syndrome.

This study evaluated the cardiorespiratory capacity of persons with MR with and without Down syndrome. Analyses of individual data records of maximal exercise tests with metabolic analyses were conducted on tests of 111 subjects (31 men and 16 women with DS; 35 men and 29 women without DS) from six participating centers. All centers used a walking treadmill protocol previously shown to produce valid and reliable maximal tests with this population. Peak oxygen uptake and peak minute ventilation were higher in men than in women (P < 0.006), and in subjects without DS (P < 0.006). Peak heart rate was also higher in subjects without DS (P < 0.006). Peak respiratory exchange ratio (RER) was higher in subjects without DS (P < 0.006). Using peak RER as a covariate did not change the results. An analysis of peak minute ventilation, heart rate and VO2 of subjects with a peak RER above 1.1 revealed the same results. These data show that individuals with mental retardation have low levels of peak VO2, consistent with low levels of cardiovascular fitness. Individuals with Down syndrome have even lower levels of peak VO2 than their peers without Down syndrome, a finding that is possibly mitigated by the lower peak heart rates of the individuals with Down syndrome.

Prediction of maximal heart rate in individuals with mental retardation.

PURPOSE: It is well known that individuals with mental retardation (MR), especially those with Down syndrome (DS), have low maximal heart rates (MHR). We evaluated the ability to predict MHR in individuals with MR and DS in comparison with persons without MR. METHODS: Subjects completed a maximal exercise test on the treadmill with metabolic and HR measurements. Stepwise multiple regression was used to develop prediction equations for subjects with MR (N = 276; 97 with DS) and without (N = 296) MR, ranging in age from 9-46 yr. RESULTS: Subjects with MR exhibited significantly lower MHR (177 vs 185 beats.min(-1)) and VO2peak (33.8 vs 35.6 mL.kg-1.min(-1)). In subjects with MR, age was a poor predictor of MHR, Y = 189 - 0.59 (age) (R = 0.30, SEE = 13.8 beats.min-1; P < 0.01), but age was a better predictor for subjects without MR, Y = 205 - 0.64 (age) (R = 0.52, SEE = 9.9 beats.min(-1); P < 0.01). A large sample Z test indicated that these regression coefficients were significantly different (P < 0.01). However, adding DS to the regression improved the prediction for subjects with MR, Y = 210 - (0.56 age) - (15.5 DS) (R = 0.57; SEE = 11.8 beats.min(-1), P < 0.01). CONCLUSION: MHR can be predicted with similar accuracy in subjects with and without MR, provided DS is accounted for in the equation for the subjects with MR.

Aerobic training exercises for individuals who had amputation of the lower limb.

The findings in ten subjects who had an amputation of the lower limb or limbs were studied before and after a fifteen-week aerobic conditioning program to determine if it improved cardiovascular fitness and reduced the effort of walking. Each subject exercised on an Air-Dyne ergometer (Schwinn, Chicago, Illinois) regularly during each week of the study period at 60 to 80 per cent of their estimated maximum heart rate. A test of maximum exercise on the ergometer and a test of walking on a treadmill were administered before and after training. After training, there was an increase of 25 per cent in the maximum capacity for exercise on the ergometer as well as significantly lower values for heart rate and consumption of oxygen during submaximum walking on the treadmill at various inclined grades. Aerobic conditioning was shown not only to improve cardiovascular fitness but also to increase the economy of walking in the subject who had an amputation of the lower limb or limbs.

An exploratory study of righting reactions from a supine to a standing position in adults with Down syndrome.

BACKGROUND AND PURPOSE: Standing from a supine position is important for physical independence. The purpose of this study was to determine the developmental level of movement in this righting task of adults with Down syndrome. SUBJECTS: Fifteen subjects (mean age = 37.6 years, SD = 18, range = 22-65) with a diagnosis of Down syndrome and mild to moderate mental retardation participated in this study. METHODS: Subjects were videotaped rising from a supine to a standing position during 10 repeated trials. The video record was analyzed to categorize the standing movements according to VanSant's descriptions. RESULTS: Sixty-four percent of the upper-extremity movements, 14.6% of the axial component movements, and 33.8% of the lower-extremity movements could not be categorized according to VanSant's descriptions. Additionally, developmentally less advanced movements dominated those movements that could be categorized. CONCLUSION AND DISCUSSION: The great variety of movements demonstrated by these subjects in the task of standing from a supine position suggests greater motor maturity than is apparent from the movement sequences described by VanSant. Identifying appropriate standing movements in persons with Down syndrome will require weighing numerous intrinsic factors (eg, physiological and anthropometric) other than motor maturity.

Effects of an aerobic rowing training regimen in young adults with Down syndrome.

Effects of a rowing exercise regimen on cardiovascular fitness of young adults with Down syndrome were examined. Sixteen young males with trisomy 21 (mean age 21.3, mean IQ 38.8) were randomly assigned to either a control or exercise group. All participants performed pre- and posttraining graded exercise tests on a treadmill and rowing ergometer. The exercise group performed a 16-week rowing ergometry training regimen. Following training, no changes in cardiovascular fitness had occurred for this group. However, they reached significantly higher levels of work performance for both treadmill and rowing ergometer posttraining tests. Results show that an exercise training regimen did not improve the cardiovascular fitness of young adults with Down syndrome but did improve exercise endurance and work capacity.

Validation of cardiovascular fitness field tests in children with mental retardation.

The validity of the 600-yard walk/run, the 20-m shuttle run, and a modified 16-m shuttle run was determined to measure aerobic capacity (VO2peak) in children with mild and moderate mental retardation. Practice sessions for all tests were conducted. All field tests were very reliable, and VO2peak was significantly related to them all. A stepwise multiple regression showed that field test performance, body mass index (BMI), and gender, but not age, were also significant predictors of VO2peak. All field tests were valid and reliable indicators of aerobic capacity, suggesting that these tests can be used to predict VO2max in children with mild and moderate mental retardation.

Isokinetic torque, average power, and flexion/extension ratios in nondisabled adults and adults with mental retardation.

For successful placement of individuals with mental retardation into community environments, a minimal amount of functional strength is required to promote self-independence. Since muscular strength and power are commonly deficient in these groups, the purpose of this study was to compare isokinetic elbow flexion and extension peak torque (Nm), average power (W), and corresponding flexion/extension ratios of adults males with Down syndrome, with mental retardation without Down syndrome, and sedentary adult males without mental retardation. Subjects with Down syndrome (N = 9), mental retardation without Down syndrome (N = 13), and without mental retardation (N = 13) were tested for elbow flexion and extension peak torque and average power at 60 and 90 degrees/sec on a Cybex 340 isokinetic dynamometer. Results indicated: 1) subjects without mental retardation displayed significantly greater ( p < 0.01) peak torque and average power elbow flexion and extension than subjects with Down syndrome and subjects with mental retardation without Down syndrome at speeds of 60 and 90 degrees/sec, and 2) there were no significant differences between groups in peak torque and average power elbow flexion/extension ratios at both angular velocities. The results of the data analysis support the premise that adults with mental retardation are in need of exercise programs to improve muscular strength.