Gait characteristics of adults with Down syndrome explain their greater metabolic rate during walking

Joint kinematics and SPM analysis of gait in children with and without Down syndrome

BACKGROUND

Individuals with Down syndrome (DS) walk with altered gait patterns compared to their typically developing (TD) peers. While walking at faster speeds and with external ankle load, preadolescents with DS demonstrate spatiotemporal and kinetic improvements. However, evidence of joint kinematic adjustments is unknown, which is imperative for targeted rehabilitation design.

RESEARCH QUESTION

How does increasing walking speed and adding ankle load affect the joint kinematics of children with and without DS during overground walking?

METHODS

In this cross-sectional observational study, thirteen children with DS aged 7-11 years and thirteen age- and sex-matched TD children completed overground walking trials. There were two speed conditions: normal speed and fast speed (as fast as possible without running). There were two load conditions: no load and ankle load (2% of body mass added bilaterally above the ankle). A motion capture system was used to register the ankle, knee, and hip joint angles in the sagittal plane. Peak flexion/extension angles, range of motion, and timing of peak angles were identified. In addition, statistical parametric mapping (SPM) was conducted to evaluate the trajectory of the ankle, knee, and hip joint angles across the entire gait cycle.

RESULTS AND SIGNIFICANCE

SPM analysis revealed the DS group walked with greater ankle, knee, and hip flexion compared to the TD group for most of the gait cycle, regardless of condition. Further, increasing walking speed led to improved ankle joint kinematics in both groups by shifting peak plantarflexion closer to toe-off. However, knee extension during stance was challenged in the DS group. Adding ankle load improved hip and knee kinematics in both groups but reduced peak plantarflexion around toe-off. The kinematic adjustments in the DS group suggest specific motor strategies to accommodate their neuromuscular deficits, which can provide a foundation to design targeted gait-based interventions for children with DS.

Development of a Physical Therapy-Based Exercise Program for Adults with Down Syndrome

In adults with Down syndrome, the combination of low physical activity and fitness levels and the high prevalence of musculoskeletal co-morbidities stresses the need for specialized exercise programs. The goal of this research study was to develop a specialized exercise program for individuals with Down syndrome using the physical therapy approach of a systems review as the foundation. We first conducted an overview of the literature on co-morbidities in adults with Down syndrome using the systems review method to categorize these findings. We extracted recommendations for content and delivery of an exercise program based on the literature review, and finally composed a specialized exercise program for individuals with Down syndrome adhering to these recommendations.

Hemodynamic and cardiorespiratory responses to submaximal and maximal exercise in adults with Down syndrome

Introduction: The genetic disorder causing Down syndrome (DS) affects the cardiorespiratory and hemodynamic parameters. When exercising, sufficient blood flow is necessary for active muscles. Cardiac output (Q) must be proportional to the peripheral requirements. In case the stroke volume (SV) is lower, the heart rate (HR) will increase further in order to maintain an adequate blood flow in the active territories (HR compensatory response). People with DS have a lower HR response to maximal exercise. Nevertheless, the response of the hemodynamic and cardiorespiratory parameters during the submaximal phases of maximal exercise was not well studied.

Objective: to evaluate cardiorespiratory and hemodynamic parameters 1) during submaximal and 2) maximal metabolic treadmill test in individuals with and without DS.

Methods: fifteen adults with DS (age = 27.33 ± 4.98 years old; n = 12 males/3 females) and 15 adults without disabilities, matched by age and sex, participated in this cross-sectional study. Peak and submaximal cardiorespiratory and hemodynamic parameters were measured during a treadmill test. Linear mixed-effects models were used to analyse interactions between the variables. Post-hoc analyses were employed to assess within and between-group differences.

Results: The DS group showed lower peak values for ventilation (VE), respiratory exchange ratio (RER), tidal volume (VT), ventilatory equivalent for O2 (VEqO2), end-tidal partial pressure for O2 (PETO2), O2 uptake (VO2) and CO2 production (all p < 0 .050), Q, SV, systolic and diastolic blood pressure (SBP, DBP), and HR (all p < 0 .050). There were group-by-time interactions (all p < 0 .050) for all ventilatory submaximal values. Significant group and time differences were observed for VE; RER; respiratory rate (RR); VEqO2; PETO2; VO2, and VT (all p < 0 .050). There were also group-by-time interactions (all p < 0 .050) and group and time differences for SBP, mean arterial blood pressure (MAP) and HR (all p < 0.010).

Conclusion: During submaximal exercise, we verified a compensatory response of HR, and greater VE and VO2 in the individuals with DS. In addition, we were able to observe that the DS group had a reduced SBP and MAP response to submaximal exercise. On the other hand, we found that adults with DS have lower peak hemodynamic and cardiorespiratory values, and a lower cardiac reserve. Further research is warranted to investigate the effects of these results on the general health of adults with DS and the impact of long-term exercise programs on these parameters.

Accelerometer-based estimation of oxygen uptake in adults with Down syndrome: vector magnitude vs. vertical axis

BACKGROUND

Triaxial accelerometer output [vector magnitude (VM) counts] may better estimate physical activity intensity as reflected in the rate of oxygen uptake (V̇O₂ ) than the traditional vertical axis (VA) counts in adults with Down syndrome (DS). This study examined the accuracy of VM vs. VA counts in estimating V̇O₂ in adults with and without DS across different physical activities and sedentary behaviours.

METHODS

Sixteen adults with DS (10 men and 6 women; 31 ± 15 years) and 19 adults without DS (10 men and 9 women; 24 ± 5 years) performed 12 tasks. V̇O₂ was measured by portable spirometer (K4b² , Cosmed) and VM and VA with an accelerometer (wGT3X-BT, Actigraph).

RESULTS

Vector magnitude and VA were significant predictors of V̇O₂ in adults with DS (P < 0.001; R²  = 0.74 and 0.65, respectively) and adults without DS (P < 0.001; P < 0.001; R²  = 0.75 and 0.61, respectively). Absolute error of prediction was significantly smaller for VM than VA for sitting, playing app, drawing, sweeping, standing and basketball (P ≤ 0.005), but smaller for VA than VM for walking at 0.8 m·s^-1 (P = 0.005). Bland-Altman plots for adults with and without DS indicated narrower limits of agreement for VM than VA (-5.57 to 5.57 and -6.44 to 6.44 mL·kg^-1 ·min^-1 ; -6.21 to 6.17 and -7.75 to 7.74 mL·kg^-1 ·min^-1 , respectively).

CONCLUSIONS

Vector magnitude and VA are significant predictors of V̇O₂ in adults with and without DS, yet VM more accurately estimated V̇O₂ than VA for most tasks. Development of accelerometer-based prediction of physical activity levels in adults with and without DS may improve by utilising VM counts.

Variability and coordination patterns of walking with different speeds in active and non-active children with Down syndrome: A cross-sectional case-control study

Purpose: Children with Down syndrome (DS) have multiple difficulties in gait pattern. So, the effect of the activity level and speed on the gait coordination and variability was investigated. Methods: In this case-control observational study, 24 participants in three groups of active and non-active children with DS, and the control group without intellectual disability were asked to walk on a treadmill with two speeds of 0.8 and 1.2 m/s. Continuous Relative Phase (CRP) and variability of CRP in thigh-leg and leg-foot coupling were assessed. Results: CRP and variability of CRP in the leg-foot coupling in the control group were significantly higher than active and non-active groups with DS. Speed led to increase the CRP of leg-foot in the active group with DS and increase the variability of this coupling in non-active group with DS. Conclusion: In this study, the activity level provided the compatibility with speed changes of walking in CRP of leg-foot in children with DS.

Predicting the rate of oxygen uptake from step counts using ActiGraph waist-worn accelerometers in adults with Down syndrome

BACKGROUND

Step rate predicts ambulatory intensity as reflected in the rate of oxygen uptake (VO₂ ) - a measure of energy expenditure. Whether step rate as measured by an accelerometer predicts VO₂ in adults with Down syndrome (DS) is unknown. We examined whether step rate predicts VO₂ in adults with and without DS. We also developed an equation for predicting VO₂ and examined its accuracy.

METHOD

Sixteen adults with DS (6 women and 10 men; age 31 ± 15 years) and 19 adults without DS (9 women and 10 men; age 25 ± 6 years) performed standing and walking at their preferred speed, 0.8 and 1.4 m·s^-1 . We measured VO₂ with a portable spirometer and step rate with a triaxial accelerometer (wGT3X-BT; ActiGraph) on the non-dominant hip, using the low-frequency extension filter. We ran multilevel regression for predicting VO₂ from linear and quadratic terms for step rate, group (1 = DS; 0 = non-DS), body mass, height, body mass index (BMI), leg length and sex. We estimated VO₂ with the resultant equation and calculated the equation's absolute per cent error, which we compared between groups.

RESULTS

VO₂ was higher in persons with than without DS only at the fast walking speed (P = 0.018). DS did not predict VO₂ . Step rate, step rate squared and BMI were significant predictors of VO₂ (P < 0.001; R²  = 0.80). Absolute error across walking speeds was 13.5-18.8% and 11.7-13.4% for adults with and without DS, respectively, and did not differ between groups or speeds.

CONCLUSIONS

Step rate, step rate squared and BMI predict VO₂ in adults with and without DS. Prediction error does not differ between groups.

Gait and postural control patterns and rehabilitation in Down syndrome: a systematic review

[Purpose] To describe (1) the current knowledge on gait and postural control in individuals with Down syndrome in terms of spatiotemporal, kinematics and kinetics, and (2) relevant rehabilitation strategies. [Methods] Randomized and non-randomized clinical trials published between January 1997 and October 2019 were selected by searching four scientific databases. We included studies on patients with Down syndrome involving gait analysis or postural control. A custom data-extraction and appraisal form was developed to collect the key features of each article. The PEDro Scale was used to evaluate the methodological quality of the studies. [Results] A total of 37 out of 146 cross-sectional and longitudinal studies were included in the review. The main abnormalities included: reduction of gait velocity and step length, poor static balance with increased anteroposterior and mediolateral oscillations and a larger step width. [Conclusion] A number of compensatory patterns during movement was observed, with a direct influence on improvements in stability and postural control throughout daily life. Intensive gait training at an early age appears to produce long-term improvements in this population. Future research should focus on the interaction between the motor and cognitive function, and on the functional effects due to the exposure to an enriched environment.

Variation in limb loading magnitude and timing in tetrapods

Comparative analyses of locomotion in tetrapods reveal two patterns of stride cycle variability. Tachymetabolic tetrapods (birds and mammals) have lower inter-cycle variation in stride duration than bradymetabolic tetrapods (amphibians, lizards, turtles and crocodilians). This pattern has been linked to the fact that birds and mammals share enlarged cerebella, relatively enlarged and heavily myelinated Ia afferents, and γ-motoneurons to their muscle spindles. Both tachymetabolic tetrapod lineages also possess an encapsulated Golgi tendon morphology, thought to provide more spatially precise information on muscle tension. The functional consequence of this derived Golgi tendon morphology has never been tested. We hypothesized that one advantage of precise information on muscle tension would be lower and more predictable limb bone stresses, achieved in tachymetabolic tetrapods by having less variable substrate reaction forces than bradymetabolic tetrapods. To test this hypothesis, we analyzed hindlimb substrate reaction forces during locomotion of 55 tetrapod species in a phylogenetic comparative framework. Variation in species means of limb loading magnitude and timing confirm that, for most of the variables analyzed, variance in hindlimb loading and timing is significantly lower in species with encapsulated versus unencapsulated Golgi tendon organs. These findings suggest that maintaining predictable limb loading provides a selective advantage for birds and mammals by allowing energy savings during locomotion, lower limb bone safety factors and quicker recovery from perturbations. The importance of variation in other biomechanical variables in explaining these patterns, such as posture, effective mechanical advantage and center-of-mass mechanics, remains to be clarified.

Triaxial accelerometer output predicts oxygen uptake in adults with Down syndrome

PURPOSE

This study examined if the relationship between the rate of oxygen uptake (V̇O₂) and output from hip-and wrist-worn accelerometers differs between adults with and without DS, and evaluated the accuracy of accelerometer output in estimating V̇O₂.

MATERIALS AND METHODS

Sixteen adults with DS (10 men) and 19 adults without DS (10 men) performed 12 tasks including physical activities and sedentary behaviors. We measured V̇O₂ with portable spirometry and accelerometer output (vector magnitude [VM]) with hip- and wrist-worn accelerometers. We used multi-level regressions to predict V̇O₂ from VM, group, body mass index (BMI), age, height, weight, and sex. We evaluated prediction accuracy with absolute percent error and Bland-Altman plots.

RESULTS

For both hip- and wrist-accelerometers, VM and group significantly predicted V̇O₂ (p ≤ 0.021). When BMI was added, BMI was a significant predictor but group was not. The final models included VM and BMI (p ≤ 0.001; R² = 0.78 and 0.57, for hip and wrist accelerometer model, respectively). Absolute error was greater for the wrist- than the hip-accelerometer model (wrist: 37.9 ± 38.1%; hip: 22.5 ± 27.4%).

CONCLUSIONS

Adults with DS have different V̇O₂ to VM responses, and this appears due to their higher BMI. Predictability of V̇O₂ from accelerometer output is better for hip- than wrist-worn accelerometers.IMPLICATIONS FOR REHABILITATIONOutput from a triaxial accelerometer has high potential in predicting the energy expenditure and classifying the intensity of physical activity and sedentary behavior in adults with Down syndrome.Accuracy of predicting energy expenditure from accelerometer output is better for hip- than wrist-worn triaxial accelerometers.The development of appropriate rehabilitation interventions that include physical activity for improving health and function in adults with Down syndrome requires accurate assessments of physical activity levels.

The association between gait variability with the energy cost of walking depends on the fall status in people with multiple sclerosis without mobility aids

BACKGROUND

Falls, gait variability and increased energy cost of walking are common in people with multiple sclerosis (PwMS). However, no studies have as yet examined this triple association in PwMS or in other neurological populations.

RESEARCH QUESTION

Does a relationship exist between gait variability, falls and the energy cost of gait in PwMS?

METHODS

This cross sectional study included 88 PwMS (50 women), mean age 39.8 (S.D = 13.0) and mean disease duration of 6.2 (SD = 8.2) years since diagnosis. Energy expenditure during walking was collected via a portable metabolic device (COSMED K5, COSMED Srl, Roma, Italy). Gait variability was measured by an electronic walkway (GAITRite™). Participants were divided into groups based on fall history (fallers and non-fallers). Differences between groups in terms of energy expenditure measures and gait variability metrics were determined by the analysis of variance test. The relationship between gait variability and energy cost of walking was examined by the Pearson's correlation coefficient test.

RESULTS

Thirty-three PwMS were classified as fallers and 55 as non-fallers. Non-significant differences between groups were observed in the energy expenditure measures, including cost of walking. Fallers demonstrated higher step length variability compared with non-fallers (4.58 (S.D. = 2.42 vs. 3.40 (S.D. = 1.40); p-value = 0.005). According to the Pearson's correlation coefficient analysis, a significant relationship was found between step length variability and energy cost of walking in the non-fallers group (Rho = 0.372, P-value = 0.006) and the total group (Rho = 0.296, p-value = 0.005), but not in those PwMS with a history of falls.

SIGNIFICANCE

We demonstrated a significant relationship between increased gait variability and energy expenditure while walking only in MS patients without a history of falls. This is important as there is evidence of the clinical relevance of increased gait variability, poor fitness level and high risk of falling in the MS population.

Gait Variability and Energy Cost of Oveground Walking in Persons With Multiple Sclerosis: A Cross-Sectional Study

OBJECTIVE

This study examined the associations between gait variability based on common spatiotemporal parameters and energetic cost of walking in persons with multiple sclerosis.

DESIGN

Eighty-six persons with multiple sclerosis underwent the 6-min walk while wearing a portable metabolic unit. The cost of walking was generated by dividing the net steady-state VO2 (milliliter per kilogram per minute) by walking speed during the 6-min walk. Participants further completed two trials of walking on the GAITRite mat at a self-selected pace for measuring spatiotemporal parameters. Variability of step length, step time, stride length, swing time, stance time, stride velocity, and single- and double-support time was indexed by the coefficient of variation.

RESULTS

Variability in the spatiotemporal variables and Expanded Disability Status Scale scores were significantly correlated with cost of walking (i.e., ρ = 0.25-0.36). Multivariate analysis revealed that disability (Expanded Disability Status Scale: β = 0.186), stance time variability (β = 1.446), and step length variability (β = -1.216) explained significant variance (R(2) = 0.38, P < 0.001) in cost of walking.

CONCLUSIONS

We provide evidence of the positive association between gait variability and cost of walking during overground walking in persons with multiple sclerosis. The findings highlight the need for interventions aiming to reduce gait variability, thereby reducing the energetic demands of walking in this population.

Effects of exercise on the physical fitness level of adults with intellectual disability: a systematic review

Purpose: To systematically review the existing scientific evidence regarding the effects of physical exercise on the fitness level of people with intellectual disabilities.Methods: Following the checklist of the Preferred Reporting Items for Systematic review and Meta-Analysis Protocols, the PubMed, CINAHL, SPORTDiscus, and Scopus databases were searched using specific keywords up to January 2018. The methodological quality of the studies found was rated by the means of specific scales according to their specific design.Results: A total of 44 studies were selected. The majority of the included studies were randomized controlled trials (n = 17), followed by non-controlled studies (n = 11), non-randomized controlled trials (n = 10), and comparative studies (n = 6). Aerobic, strengthening, and combined exercise programs were the most frequently proposed interventions. Exercise showed to have significant effects on the cardiorespiratory and muscular fitness. Not all the selected studies reported improvements in parameters related to body composition.Conclusions: There is sufficient scientific evidence for the beneficial effects of exercise on the cardiovascular and muscular fitness of adults with mild/moderate ID. There is a need for more studies focused on the impact of physical exercise on the body composition of this population, and those that aim at identifying the impact of alternative interventions.IMPLICATIONS FOR REHABILITATIONThere is a need for basic guidelines that can help rehabilitation professionals to prescribe exercise for maintaining and improving physical fitness in the adults with intellectual disabilities.In adults with intellectual disabilities, aerobic exercise has beneficial effects on cardiovascular and muscular fitness, flexibility, and range of motion.No firm conclusion can be made regarding the effects of aerobic, muscular, and combined training programs on the body composition of adults with intellectual disabilities.Rehabilitation professionals should be aware that scientific evidence regarding the prescription of alternative exercise protocols in adults with intellectual disabilities (i.e. dancing, water-based exercise, animal therapy, etc) is scarce.

Physical Activity Promotion for Persons Experiencing Disability: The Importance of Interdisciplinary Research and Practice

This paper examines the need for interdisciplinary knowledge in the formation of public health models for health-promoting physical activity (PA) for people experiencing disability. PA promotion for people experiencing disability is a multifaceted endeavor and requires navigating a multitude of complicated and interactive factors. Both disability and health are multifaceted constructs and the relationship between PA and health is embedded within a complicated web of interactive influences. PA promotion must consider interacting biological and psychosocial factors within the person and in the sociopolitical environment. Models for research and practice need to evolve from value and belief systems that center on people experiencing disability without stigmatizing them. We argue that interdisciplinary research and practice is needed in navigating the intricacies of PA promotion toward improving the health of people experiencing disability and facilitating inclusion, empowerment, and dignity.

Gait Characteristics of Adults With Intellectual Disability

Gait is a relevant and complex aspect of motor functioning. Disturbances are related to negative health outcomes. Gait characteristics of 31 adults with intellectual disability (ID) without Down syndrome (DS) (42.77±16.70 years) were investigated, and associations with age, sex, body mass index (BMI), and level of ID were assessed. Sex and BMI were significantly associated with some of the gait parameters, while age and level of ID were not. Gait characteristics of adults with ID seem to be comparable to those of the general population of older adults (average 20 years older), except that adults with ID seem to spend less time in stance and double support phase and walk more variable and with a broader base of support.

Prediction of energy expenditure during walking in adults with down syndrome

BACKGROUND

When developing walking programmes for improving health in adults with Down syndrome (DS), physical activity professionals are in need of an equation for predicting energy expenditure. We therefore developed and cross-validated an equation for predicting the rate of oxygen uptake (VO₂ ; an index of energy expenditure) for adults with and without DS.

METHOD

A total of 469 VO₂ observations during walking across different speeds were available from 54 adults with DS and 61 adults without DS.

RESULTS

Significant predictors of VO₂ were speed, speed square, group and group-by-speed interaction. Separate models for each group showed that speed and its square significantly predicted VO₂ . Absolute per cent error was small and did not differ between groups.

CONCLUSION

Adults with DS have different VO₂ response to walking speed from persons without DS. VO₂ is predicted from speed with acceptable accuracy for persons with DS.