Reduced metaboreflex control of blood pressure during exercise in individuals with intellectual disability: a possible contributor to exercise intolerance

Effects of rope skipping exercise on physical, cardiovascular fitness and exercise tolerance in adolescent students with moderate intellectual disability

BACKGROUND

Adolescents with intellectual disabilities (ID) who live a sedentary lifestyle may lead to an increased risk of chronic cardiovascular disease in adulthood. The aim of this study is to investigate the effects of 8-week progressive rope skipping training on physical, cardiovascular fitness and exercise tolerance of high school students with moderate ID.

METHODS

Thirty-four senior high school with ID (aged 15-18 years old) were randomised into experimental group received progressive skipping rope exercise (RS, n = 17) and control group no rope skipping exercise intervention group (CON, n = 17). The RS group were received progressive rope skipping exercise for 50 min each time, three times a week, for 8 weeks. The control group was not allowed to participate in intervention activities during the study period. The physical fitness, body composition, arterial stiffness index (ASI) and blood pressure were measured before and after the 8-week intervention.

RESULTS

After the 8-week progressive skipping rope exercise intervention, the participants from the RS group increased in the 3-min step test, sit-up test, grip strength and sit and reach test, when compared to the baseline (P < 0.05). The RS group exhibited lower the area under curve of heart rate (HR) during post-exercise recovery (P < 0.05). The participants in the RS group showed significant decreases in systolic (SBP) and diastolic (DBP) blood pressure, mean arterial pressure (MAP) and HR when compared to the baseline (P < 0.05). Change SBP has moderate positive correlation with change ASI.

CONCLUSIONS

The results of this experiment suggest that progressive rope skipping exercise might improve physical fitness and promote cardiovascular health, as well as enhance exercise tolerance for adolescent students with moderate ID.

The Effect of Progressive Resistance Exercise Training on Cardiovascular Risk Factors in People with Intellectual Disabilities: A Study Protocol

Progressive resistance exercise training (PRET) reduces cardiovascular risk factors (CVRF) in the general population. It is unknown if PRET also reduces these risk factors in adults with intellectual disabilities (ID). The aim is to present the protocol of an intervention study that investigates the effect of PRET on CVRF in adults with ID. We will use a repeated time series design with one study group. Adults with mild-to-moderate ID and at least two CVRF are eligible (Netherlands Trial Register, NL8382). During a 12-week baseline period, measurements take place at a 6-week interval. After this, the PRET programme starts for 24 weeks, after which all measurements will be repeated. We will use hierarchical regression models, adjusted for sport activity and medication use, to estimate the effect of PRET. After the intervention, the participants will be followed-up for 12 weeks. We will evaluate factors for successful implementation of exercise in daily life. Primary outcomes are: hypertension, obesity, hypercholesterolemia, diabetes, metabolic syndrome. Secondary outcomes are: physical fitness, sarcopenia, physical activity, activities of daily living, falls, challenging behaviour. If our results show that the PRET programme is effective, it may be a promising non-pharmacological intervention to reduce CVRF in adults with ID.

Cardiac Autonomic Modulation Response Before, During, and After Submaximal Exercise in Older Adults With Intellectual Disability

The analysis of the heart rate variability (HRV) consists of changes in the time intervals between consecutive R waves. It provides information on the autonomic nervous system regulation and it is a predictor of adverse cardiovascular events. Several studies analyzed this parameter in youth and adults with Intellectual Disability (ID). Nevertheless, there is a lack of information regarding the HRV before, during, and after exercise in older adults with ID. Therefore, we aimed to describe and compare the cardiac autonomic modulation before, during, and after the six-minute walk test (6MWT) in older adults with and without ID. Twenty-four volunteers with ID and 24 without ID (non-ID) participated in this study. HRV was assessed by R-R intervals at rest, during and after the 6MWT. At rest and recovery periods, the participants remained sited. The symbolic analysis was used to evaluate non-linear HRV components. The recovery HR kinetics was assessed by the mean response time, which is equivalent to time constant (τ)+time delay (TD). Between groups differences in HRV variables were not significant. During the recovery period, HR kinetics time variables showed significant better results in non-ID participants (TD: 6±5s vs. 15±11s; τ: 19±10s vs. 35±17s; and MRT: 25±9s vs. 50±11s, all p<0.050). In conclusion, our results suggest that the HRV in older adults with and without ID is similar during rest, exercise, and recovery. Recovery HR kinetics after the 6MWT was slower in older adults with ID. The reason for these results may be a reduced post-exercise vagal rebound in older adults with ID.

Cardiorespiratory Coordination During Exercise in Adults With Down Syndrome

Introduction: Down syndrome (DS) is a chromosomal disorder affecting simultaneously cardiovascular and respiratory systems. There is no research studying the coupling between these systems during cardiorespiratory exercise testing in a population with DS. Cardiorespiratory coordination (CRC), evaluated through principal component analysis (PCA), measures the covariation of cardiorespiratory variables during exercise.

Objective: To investigate and compare CRC in adults with and without DS during maximal cardiorespiratory exercise testing.

Methods: Fifteen adults with DS and 15 adults without disabilities performed a maximal cardiorespiratory exercise test on a treadmill. First, the slope, and afterward the velocity was increased regularly until participants reached exhaustion. The time series of six selected cardiorespiratory variables [ventilation per minute, an expired fraction of O₂, the expired fraction of CO₂, heart rate, systolic blood pressure (SBP), and diastolic blood pressure (DBP)] were extracted for the analysis. The number of principal components (PCs), the first PC eigenvalues (PC₁), and the information entropy were computed for each group (non-DS and DS) and compared using a t-test or a Mann-Whitney U test.

Results: Two PCs in the non-DS group and three PCs in the DS group captured the variance of the studied cardiorespiratory variables. The formation of an additional PC in the DS group was the result of the shift of SBP and DBP from the PC₁ cluster of variables. Eigenvalues of PC₁ were higher in the non-DS (U = 30; p = 0.02; d = 1.47) than in the DS group, and the entropy measure was higher in the DS compared with the non-DS group (U = 37.5; p = 0.008; d = 0.70).

Conclusion: Adults with Down syndrome showed higher CRC dimensionality and a higher entropy measure than participants without disabilities. Both findings point toward a lower efficiency of the cardiorespiratory function during exercise in participants with DS. CRC appears as an alternative measure to investigate the cardiorespiratory function and its response to exercise in the DS population.

Hemodynamic Response to Isometric Handgrip Exercise in Adults with Intellectual Disability

INTRODUCTION

Individuals with intellectual disability (ID) have an increased risk of cardiovascular disease and reduced work capacity, which could partly be explained by alterations to autonomic and hemodynamic regulation. The measurement of heart rate and blood pressure during isometric handgrip (HG) exercise, a sympathoexcitatory stimulus, is a noninvasive method to investigate autonomic and hemodynamic alterations. The purpose of this study was to assess alterations to autonomic and associated hemodynamic regulation between individuals with ID and a matched control group during isometric HG exercise.

METHODS

Individuals with ID (n = 13; 31 ± 2 yr, 27.6 ± 7.7 kg·m-2) and without ID (n = 16; 29 ± 7 yr, 24.2 ± 2.8 kg·m-2) performed 2 min of isometric HG exercise at 30% of maximal voluntary contraction (MVC) in the seated position. Blood pressure was averaged for 2 min before, during, and after HG exercise (mean arterial pressure [MAP], systolic blood pressure, and diastolic blood pressure). Heart rate variability, blood pressure variability, and baroreflex sensitivity were calculated from the continuous blood pressure and heart rate recordings.

RESULTS

Isometric HG elicited a blunted response in systolic blood pressure, diastolic blood pressure, and MAP among individuals with ID compared with individuals without ID, even after controlling for strength (MAP: rest, HG, recovery; ID: 103 ± 7, 108 ± 9, 103 ± 7; without ID: 102 ± 7, 116 ± 10, 104 ± 10 mm Hg; interaction P < 0.05). Individuals with ID also had an attenuated baroreflex sensitivity response to HG exercise compared with individuals without ID (interaction P = 0.041), but these effects were no longer significant after controlling for maximal voluntary contraction. Indices of heart rate variability and blood pressure variability were not different between groups overall or in response to HG exercise (P > 0.05).

CONCLUSIONS

Individuals with ID have a blunted hemodynamic and autonomic response to isometric HG exercise compared with individuals without ID.

Does the number of trials affect the reliability of handgrip strength measurement in individuals with intellectual disabilities?

The main objectives of this study were to examine which testing protocol (one/two/three trials) and method (best/average value) used for determining maximal handgrip strength is more reliable for individuals with intellectual disabilities (ID) and to compare the reliability and variability of maximal handgrip strength measurement between individuals with ID and healthy individuals. Twenty individuals with ID (18.7±3.3 years) and 20 healthy individuals (18.5±3.4 years) performed six separate sessions. During these sessions, the participants' maximal handgrip strength was evaluated using three protocols with different number of trials (one/two/three). In individuals with ID, the protocols with one and two trials were less reliable (ICC=0.78-0.95; SEM%=9-21) than the protocol with three trials (ICC=0.94-0.96; SEM%=8-10) whereas in healthy individuals all protocols were equally reliable (ICC=0.95-0.99; SEM%=1.9-4.9). In individuals with ID, the mean of three trials (ICC=0.96, SEM=1.19-1.35kg, SEM%=8.2-8.7) had slightly higher reliability than the best of three trials (ICC=0.94, SEM=1.47-1.75kg, SEM%=9.2-10.1). Furthermore, the variability of maximal handgrip strength measurement was about twofold higher in individuals with ID (CV=37-45%) vs. healthy individuals (CV=21-23%). Maximal handgrip strength can be measured reliably in young individuals with ID using the mean of three trials as the most reliable approach for the determination of maximal handgrip strength.

Diminished Blood Pressure Profiles in Children With Down Syndrome

This study sought to analyze blood pressure trends in children with Down syndrome at multiple centers. A multicenter, retrospective, cross-sectional study was performed. All patients were <18 years and had a diagnosis of Down syndrome. Existing comorbidities were nonexclusionary. For each patient, 3 blood pressure recordings were obtained from routine clinic visits. In total, 887 patients with 2661 total blood pressure recordings were included in this study. The average blood pressure percentile for patients was 38.87 with a median percentile of 31.5. Age, sex, and race were not predictive of blood pressure percentile. Compared with established data from the National Heart Lung and Blood Institute and National Health and Nutrition Examination Survey cohort (ages 8-18 years), blood pressure in our Down syndrome population was statistically lower by 6.1 percentile points (P<0.001), with the greatest difference at higher blood pressure percentiles (P<0.001). Only 10% of all Down syndrome cohort blood pressure recordings were greater than the National Heart Lung and Blood Institute/National Health and Nutrition Examination Survey 70th percentile, with no patients meeting criteria for prehypertension or hypertension. Additional comparisons against American Academy of Pediatrics data were similar and statistically significant. In children with Down syndrome, there is a 12 percentile point reduction in baseline blood pressure compared with age- and height-matched controls reported in the National Heart Lung and Blood Institute/National Health and Nutrition Examination Survey and American Academy of Pediatrics cohorts. This data can potentially be utilized in the evaluation and care of persons with Down syndrome in their pediatric medical homes.

Pacing Profiles in Competitive Track Races: Regulation of Exercise Intensity Is Related to Cognitive Ability

Pacing has been defined as the goal-directed regulation of exercise intensity over an exercise bout, in which athletes need to decide how and when to invest their energy. The purpose of this study was to explore if the regulation of exercise intensity during competitive track races is different between runners with and without intellectual impairment, which is characterized by significant limitations in intellectual functioning (IQ ≤ 75) and adaptive behavioral deficits, diagnosed before the age of 18. The samples included elite runners with intellectual impairment (N = 36) and a comparison group of world class runners without impairment (N = 39), of which 47 were 400 m runners (all male) and 28 were 1500 m-runners (15 male and 13 female). Pacing was analyzed by means of 100 m split times (for 400 m races) and 200 m split times (for 1500 m races). Based on the split times, the average velocity was calculated for four segments of the races. Velocity fluctuations were defined as the differences in velocity between consecutive race segments. A mixed model ANOVA revealed significant differences in pacing profiles between runners with and without intellectual impairment (p < 0.05). Maximal velocity of elite 400 m runners with intellectual impairment in the first race segment (7.9 ± 0.3 m/s) was well below the top-velocity reached by world level 400 m runners without intellectual impairment (8.9 ± 0.2 m/s), and their overall pace was slower (F = 120.7, p < 0.05). In addition, both groups followed a different pacing profile and inter-individual differences in pacing profiles were larger, with differences most pronounced for 1500 m races. Whereas, male 1500 m-runners without intellectual impairment reached a high velocity in the first 100 m (7.2 ± 0.1 m/s), slowly decelerated in the second race segment (−0.6 ± 0.1 m/s), and finished with an end sprint (+0.9 ± 0.1 m/s); the 1500 m runners with intellectual impairment started slower (6.1 ± 0.3 m/s), accelerated in the second segment (+0.2 ± 0.7 m/s), and then slowly decreased until the finish (F = 6.8, p < 0.05). Our findings support the hypothesis that runners with intellectual impairment have difficulties to efficiently self-regulate their exercise intensity. Their limited cognitive resources may constrain the successful integration of appropriate pacing strategies during competitive races.

Heart rate recovery after the 10-m incremental shuttle walking test in older adults with intellectual disabilities

Heart rate recovery (HRR) after exercise is an independent predictor for cardiovascular and all-cause mortality. To investigate the usefulness of HRR in cardiorespiratory exercise testing in older adults with intellectual disabilities (ID), the aims of this study were (a) to assess HRR in older adults with ID after the 10-m incremental shuttle walking test (ISWT) and (b) its association with personal characteristics (gender, age, distance walked on the ISWT, level of ID, genetic syndrome causing ID, autism, behavioral problems, and peak heart rate (HRpeak)). HRR was assessed after the 10-m incremental shuttle walking test in 300 older adults (>50 years) with borderline to profound ID. HRR was defined as the change from HRpeak during the ISWT to heart rate measured after 1, 2, 3, 4, and 5 min of passive recovery. The largest decrease in heart rate was in the first minute of recovery leveling off toward the fifth minute of recovery. An abnormal HHR (≤12 bpm) was seen in 36.1% of the participants with Down syndrome (DS) and in 30.7% of the participants with ID by other causes. After the fifth minute the heart rates of 69.4% of the participants with DS and of 61.4% of the participants with ID by other causes returned to resting levels. HRpeak and distance walked on the ISWT were positively related to all HRR measures. More severe ID was negatively related and having DS positively related to HRR after 3-5 min of recovery. The other characteristics were not significantly associated to HRR. HRR is a potentially useful outcome measure in cardiorespiratory fitness testing of older adults with ID with a direct, objective, and non-invasive measurement. Further research is needed to identify the relation between HRR and adverse health outcomes in this population.