Functional Electrical Stimulation‐Supported Interval Training Following Sensorimotor‐Complete Spinal Cord Injury: A Case Series

Objective. To investigate the effect of interval training supported by Functional Electrical Stimulation (FES) on ambulation ability in complete spinal cord injury (SCI). Methods. We trained four men with sensorimotor‐complete (ASIA A) SCI, who achieved gait through FES of the quadriceps femoris, gluteus maximus, and common peroneal nerve on each side on a motorized treadmill. Training involved progressive interval walking exercise, consisting of periods of activity followed by equal periods of rest, repeated until muscle fatigue. We used time to muscle fatigue during continuous treadmill ambulation as the primary outcome measure. We also recorded the patterns of incremental stimulation for all training and testing sessions. Results. All subjects increased their ambulation capacity; however, the responses varied from subject to subject. Some subjects increased the total distance walked by as much as 300% with progressive improvement over the entire training period; however, others made more modest gains and appeared to reach a performance plateau within a few training sessions. Conclusions. FES‐supported interval training offers a useful and effective strategy for strength‐endurance improvement in the large muscle groups of the lower limb in motor‐complete SCI. We believe that this training protocol offers a viable alternative to that of continuous walking training in people with SCI using FES to aid ambulation.     

Hip flexor fatigue limits walking in Charcot–Marie–Tooth disease

Charcot–Marie–Tooth (CMT) disease results in distal lower limb weakness that affects walking. In this study we assess the role of the hip flexors in compensating for distal weakness while walking and the effects of prolonged walking on these putative compensatory strategies. Eighteen subjects with CMT disease were compared with 14 matched controls while they walked on a treadmill to a predetermined point of perceived effort. A significant reduction was observed in peak hip flexor velocity during walking and hip flexor maximal voluntary contraction. In a second session following selective fatigue of the hip flexors, hip flexor velocity decreased immediately on walking, and walking duration was greatly reduced. This study suggests that hip flexors compensate for distal weakness and that fatigue in the hip flexors can limit walking duration. Treatments directed toward improving proximal muscle strength may therefore help to delay onset of hip flexor fatigue and thus prolong walking duration. Muscle Nerve, 2009     

Benefits of interval-training on fatigue and functional capacities in Charcot-Marie-Tooth disease

Exercise intolerance and undue fatigue are common complaints in patients with Charcot-Marie-Tooth (CMT) disease. Reduced physical ability is due directly to the disease, but it is also due to physical deconditioning. The aim of this study was to test whether 24 weeks of interval-training exercise (ITE) cycling can significantly improve physiological, neuromuscular, and functional capacities and alleviate fatigue in CMT patients. Eight CMT patients (4 CMT1A and 4 CMT2) participated in ITE for 3 nonconsecutive days per week. Cardiovascular fitness, muscle strength, fatigue resistance, and functional capacities were measured before and after 12 weeks of supervised hospital training and again after another 12 weeks of unsupervised home training. Training was well tolerated. There were significant improvements in cardiorespiratory capacities, isokinetic concentric strength, and functional ability measurements. All patients experienced an improvement in their self-reported visual analogic scale for fatigue and pain during training. However, there was no significant change in their isometric force production and indices of fatigue resistance after training. Although the improvement in exercise tolerance may be due in part to reversal of the deconditioning effect of their related sedentary lifestyle, this clinical trial suggests that ITE can benefit CMT patients especially in their functional performance and subjective perception of pain and fatigue. Moreover, the improvement observed at the end of the first supervised period ITE was maintained after the second unsupervised home period, although there was no further improvement in performance and tolerance.     

Meta-analysis of the effect of strengthening interventions in individuals with cerebral palsy

This study aimed to investigate the evidence that strengthening interventions can improve muscle strength and activity in individuals with cerebral palsy. The search focused on studies that employed strength training for children with cerebral palsy for which six electronic databases were used to extract literature published from 2001 to 2012. The key terms used in these searches were combined strength training, strengthening, weight training, weight lifting, resistance, and cerebral palsy. The quality of each study was assessed using the PEDro (Physiotherapy Evidence Database) scale. Thirteen randomized controlled trial studies were selected and divided into categories according to program type, mode, and outcome measures. The overall effect sizes of each study and types of strengthening were large. Strengthening exercise improved muscle strength to a greater degree, when practiced 3 times per week in 40–50 min sessions than in other categories of session length, and greater improvement was observed in younger children than in older. The effect size of the activities and variables related to gait, except for gait endurance, were medium to large. The effect size of individual muscles was large, but the effect sizes for ankle plantar flexor, hip abductor/adductor, and extensor were insignificant. Strengthening interventions are useful for increasing muscle strength in individuals with cerebral palsy, specifically in youth and children, and optimal exercise consisted of 40- to 50-min sessions performed 3 times per week. Although strengthening interventions may improve activities, including gait, more studies that are rigorous are needed to determine the contributions to gross motor function.     

Relationship between physical performance and quality of life in Charcot‐Marie‐Tooth disease: a pilot study

Charcot‐Marie‐Tooth (CMT) is a rare inherited peripheral neuropathy in which quality of life (QoL) is reduced compared with the general population. This paper investigates the relationship between QoL and physical performance in people with CMT with the aim of identifying avenues for future research into rehabilitation strategies. Cross‐sectional data was obtained from 10 participants (5 men, 5 women, age 46 ± 13 years, height 1.7 ± 0.1 m, body mass 77 ± 17 kg) with CMT (CMT1A n = 5; CMT‐X n = 3; unknown genetic origin n = 2). Participants were evaluated for QoL, falls efficacy (FES), balance, mobility, muscle strength, and power. Physical component score (PCS) of the Short Form‐36 (SF‐36) was significantly and directly related to higher leg press power (r = 0.75, p = 0.02). Better FES scores were significantly related to faster habitual gait speed (r = ?0.70, p = 0.02), left hip abduction, and seated row strength (r = ?0.68, p = 0.03; r = ?0.73, p = 0.03, respectively). Future research should aim to substantiate these preliminary findings in a larger cohort and investigate whether interventions targeting muscle strength and power can improve QoL and mobility outcomes in people with CMT.     

Le réentraînement à l’effort chez l’enfant atteint de paralysie cérébrale (PC). Revue de littérature

The exercise training now appears to be an effective way to combat and reduce the chronic deficiencies in adults with chronic pathology and more recently in the adolescent (or child) suffering from neurological disorders, including cerebral palsy. Numerous studies to date have produced encouraging results in improving some quality of life factors in young patients with cerebral palsy. Firstly, a rehabilitation training based on exercises carried out in endurance improves aerobic capacity and the distance and speed of walking and the GMFCS. A strength training will help improve muscle mass and GMFCS as well. Finally, the type of exercise training to focus now is a “mixed” training, i.e. based on exercises involving the two training protocol before. But to clarify the procedures for carrying out such training, it will take into account various parameters such as muscle fatigue.     

Gait performance in dementia: the effects of a 6-week resistance training program in an adult day-care setting

BACKGROUND: Age-related declines in balance and muscle power are largely responsible for the changes in the various components of gait performance among elderly people. But these can often be remedied with strength training. People with cognitive impairment frequently demonstrate impaired gait, putting them at increased risks for falls and serious injury. OBJECTIVES: This paper reports on the effects of a six-week pilot study of moderate intensity strength training on the gait of elderly individuals with dementia who attend a day-care center. METHODS: Twenty-six adults (23 female, three male), age = 79.2 +/- 6.6 years, completed the study. Each subject completed a baseline assessment of lower extremity strength and gait. Gait was evaluated using free- and fast-gait speed over a 6-meter course, the Tinetti-Gait Assessment scale, the 'Timed-Up-and-Go', and the Gait Assessment Rating Scale (GARS). The intervention consisted of moderate-intensity progressive resistance lower extremity exercise using Theraband, for two to three sessions per week over the six weeks. Post-intervention assessment of strength and gait was repeated at the completion of the sixth week. Multiple paired t-tests were calculated for each outcome measure. RESULTS: The baseline assessment of gait suggests a high degree of frailty and risk for falls in the sample. Although post-intervention scores reflected improvement on all gait measures, the only statistically significant change observed was in fast-gait time. CONCLUSION: A six-week resistance training program proved to be of insufficient duration, intensity or specificity to produce significant change in gait outcome measures, with the exception of fast speed gait.     

Improved gait parameters after robotic‐assisted locomotor treadmill therapy in a 6‐year‐old child with cerebral palsy

Task‐specific body‐weight‐supported treadmill therapy improves walking performance in children with central gait impairment. Modulation of spinal networks and improvement of muscle energy consumption are thought to contribute to this effect. Robotic‐assisted treadmill therapy enabled by a driven gait orthosis (DGO) has been established for adults and shown to provide significant improvements in individuals with spinal cord injury and stroke. Recently a pediatric DGO has been developed. Here, we report the results of a 3‐week trial of robotic‐assisted treadmill therapy of a 6‐year‐old boy with bilateral spastic cerebral palsy. The boy tolerated the trial very well and showed improved function, speed, and endurance of walking. Introducing methods of robotic medicine to pediatrics may help children with central gait impairment to regain motor function. © 2007 Movement Disorder Society     

Established and novel measures of upper limb impairment in children with Charcot‐Marie‐tooth disease type 1A and riboflavin transporter deficiency type 2

Hand function is a problem in patients with Charcot‐Marie‐Tooth disease type 1A (CMT1A) and Riboflavin Transporter Deficiency type 2 (RTD2). However, a detailed understanding of upper limb involvement in these conditions is lacking. The aim of this pilot study was to compare hand and upper limb function between children with CMT1A, RTD2 and healthy controls using established and novel outcome measures. Three age‐and sex‐matched groups of four children (5–15 years, 1 male/group) with CMT1A, RTD2, and healthy controls were assessed for function, strength, and sensation. Fatigue and muscle activity of the FDI was also assessed using a submaximal contraction at 40% of the participants' maximal voluntary contraction. Functional measures were most affected in children with RTD2 followed by children with CMT1A, compared to healthy controls. Strength was similarly impaired in CMT1A and RTD2 compared to controls (p < 0.05). Sensation was significantly impaired in RTD2 compared to CMT1A and controls (p = 0.008). While time to fatigue did not differ between groups, a decline in muscle activity while force remained constant showed that controls compensated with other muscles during the fatigue task while children with CMT1A and RTD2 did not have this compensatory ability. Children with CMT1A and RTD2 exhibited marked hand/upper limb impairment. These results suggest the upper limb should be a focus of rehabilitative therapy in affected children using sensitive outcome measures of strength and sensation, as well as functional activities of daily living, which are most relevant to the patient.     

Can aerobic treadmill training reduce the effort of walking and fatigue in people with multiple sclerosis: a pilot study

Impaired mobility in multiple sclerosis (MS) is associated with high-energy costs and effort when walking, gait abnormalities, poor endurance and fatigue. This repeated measures trial with blinded assessments investigated the effect of treadmill walking at an aerobic training intensity in 16 adults with MS. The intervention consisted of 12 sessions of up to 30 minutes treadmill training (TT), at 55-85% of age-predicted maximum heart rate. The primary outcome measure was walking effort, measured by oxygen consumption (mL/kg per metre), during treadmill walking at comfortable walking speed (CWS). Associated changes in gait parameters using the 'Gait-Rite' mat, 10-m time and 2-minute distance, and Fatigue Severity Scale were examined. Following training, oxygen consumption decreased at rest (P = 0.008), CWS increased (P = 0.002), and 10-m times (P = 0.032) and walking endurance (P = 0.020) increased. At increased CWS, oxygen consumption decreased (P = 0.020), with a decreased time spent in stance in the weaker leg (P = 0.034), and a greater stride distance with the stronger leg (P = 0.044). Reported fatigue levels remained the same. Aerobic TT presents the opportunity to alter a motor skill and reduce the effort of walking, whilst addressing cardiovascular de-conditioning, thereby, potentially reducing effort and fatigue for some people with MS.     

Systematic review of exercise for Charcot‐Marie‐Tooth disease

Charcot‐Marie‐Tooth disease (CMT) is a slowly progressive hereditary degenerative disease and one of the most common neuromuscular disorders. Exercise may be beneficial to maintain strength and function for people with CMT, however, no comprehensive evaluation of the benefits and risks of exercise have been conducted. A systematic review was completed searching numerous electronic databases from earliest records to February 2015. Studies of any design including participants of any age with confirmed diagnosis of CMT that investigated the effects of exercise were eligible for inclusion. Of 13,301 articles identified following removal of duplicates, 11 articles including 9 unique studies met the criteria. Methodological quality of studies was moderate, sample sizes were small, and interventions and outcome measures used varied widely. Although the majority of the studies identified changes in one or more outcome measurements across exercise modalities, the majority were non‐significant, possibly due to Type II errors. Significant effects described included improvements in strength, functional activities, and physiological adaptations following exercise. Despite many studies showing changes in strength and function following exercise, findings of this review should be met with caution due to the few studies available and moderate quality of evidence. Well‐powered studies, harmonisation of outcome measures, and clearly described interventions across studies would improve the quality and comparability of the evidence base. The optimal exercise modality and intensity for people with CMT as well as the long‐term safety of exercise remain unclear.     

Nonvolitional assessment of muscle endurance in idiopathic inflammatory myopathies: There is no relationship between patient‐reported fatigue and muscle fatigability

Introduction: We investigated whether muscle endurance differs between IIM patients and controls and if a relationship exists between perceived fatigue and poor muscle endurance. Methods: Quadriceps contractility, measured using femoral nerve stimulation (TwQ), and strength, measured using maximal voluntary contraction (MVCQ), were assessed in 20 IIM patients and matched controls. Quadriceps endurance was assessed using repetitive electrical stimulation (3 minutes). Time for force to fall to 70% initial force was determined (T70). Reported fatigue was measured using the FACIT‐F/Fatigue Severity Scales. Results: TwQ and MVCQ were lower and perceived fatigue greater for patients. There was no difference in T70 between groups. No relationships were observed between perceived fatigue and endurance (T70). Conclusions: IIM patients reported more fatigue and were weaker than controls, but there was no difference in muscle endurance. Endurance and strength were unrelated to reported fatigue measures. Mechanisms driving perceived IIM fatigue are likely to be multifactorial. Muscle Nerve 50 : 401–406, 2014     

Foot drop splints improve proximal as well as distal leg control during gait in Charcot‐Marie‐Tooth Disease

Introduction: During walking, people with Charcot‐Marie‐Tooth (CMT) disease may compensate for distal weakness by using proximal muscles. We investigated the effect of different AFOs on distal leg control and proximal compensatory actions. Methods: Fourteen people with CMT were tested while wearing 3 types of ankle‐foot orthosis (AFO) bilaterally compared with shoes alone. Walking was assessed using three‐dimensional gait analysis. Stiffness of the splints was measured by applying controlled 5‐degree ankle stretches using a motor. Results: The results showed that each AFO significantly stiffened the ankle and increased ankle dorsiflexion at foot clearance compared with shoes alone. At push off, peak ankle power generation was reduced, but only with 1 type of AFO. A significant decrease in hip flexion amplitude during the swing phase was observed with all 3 AFOs. Conclusions: These results indicate that AFOs reduce foot drop and remove the need for some proximal compensatory action. Muscle Nerve 46: 512–519, 2012     

Effect of low dose robotic-gait training on walking capacity in children and adolescents with cerebral palsy

ObjectiveRobotic gait training presents a promising training modality. Nevertheless, evidence supporting the efficacy of such therapy in children with cerebral palsy remains insufficient. This study aimed to assess the effect of robotic gait training in children/adolescents with cerebral palsy.MethodsTwenty-four children/adolescents with bilateral cerebral palsy (12 female, 10.1 ± 3.1 years, Gross Motor Function Classification System II to IV) took part in this study. They received two 30−45 min sessions/week of Lokomat training for 12-weeks. Muscle strengths, 6-min walk exercise and gait parameters were evaluated pre- and post-training and at 6-months-follow-up. Training effect according to the level of impairment severity (moderate vs severe) was analyzed using a change from the baseline procedure.ResultsA significant increase in muscle strength was observed after training (p ≤ 0.01). Hip flexors and knee extensors strength changes were maintained or improved at follow-up (p < 0.05). Comfortable walking speed was significantly increased by +20% after training with a slight reduction at follow-up compared to post-training condition (−2.7%, p < 0.05). A significant step length increase was observed after training (14%, p ≤ 0.001). The distance covered in 6 min was higher in post-training (+24%, p ≤ 0.001) and maintained at follow-up compared to pre-training conditions. No significant changes in kinematic patterns were observed. The analysis by subgroup showed that both groups of children (with moderate and severe impairments) improved muscle strength and walking capacities after Lokomat training.ConclusionThe suggested Lokomat training induced improvement in walking capacity of children/adolescents with cerebral palsy whatever the level of severity. Hence, Lokomat training could be viewed as a valuable training modality in this population.     

A pilot randomised controlled trial of a home-based exercise programme aimed at improving endurance and function in adults with neuromuscular disorders

Aim

To investigate the feasibility and effect of a home‐based exercise programme on walking endurance, muscle strength, fatigue and function in people with neuromuscular disorders (NMDs).

Methods

20 adults with NMDs recruited to a control (n = 11) or exercise (n = 9) group were assessed by blinded assessors at baseline and at week 8. Walking and strengthening exercises were given to the exercise group in an 8‐week home exercise programme. A 2‐min walk distance was the main outcome measurement; isometric muscle strength, fatigue and function were secondary measurements.

Results

2‐min walk distances were not found to change in either group (p>0.05; control: mean 14.50 (SD 22.06) m; exercise: mean 2.88 (SD 20.08) m), and no difference was observed in the change scores between groups (p>0.05). Leg muscle strength increased in the exercise group (p<0.05) but not in the control group (p>0.05). Significance was reached between the groups with respect to the difference in change in muscle strength scores in the right quadriceps (p<0.05; control: mean −2.82 (SD 4.87) kg; exercise: mean −7.08 (SD 2.82) kg). No change was observed in fatigue or function scores (p<0.05).

Conclusions

A home‐based approach aimed at improving endurance in adults with NMDs is feasible and further investigation on a larger sample is warranted.People with neuromuscular diseases (NMDs) may lead a relatively sedentary lifestyle, causing secondary detraining.¹ Regular exercise leads to health and social benefits even in people with disease.² The limited clinical research on adults with NMD suggests that they benefit from targeted aerobic and muscle training exercise programmes.^3,4 These interventions may be effectively provided in the community setting^5,6 and are more effective if supported by a therapist.⁷Patients with NMD in the UK receive specialist support from regional centres, which may be located some distance from their home. We developed a training programme that could be delivered with a single demonstration of exercises in the clinic, with follow‐up support delivered through a leaflet and by telephone. We carried out a pilot investigation on the effect of an exercise programme on walking distance, specifically developed for the treatment of a range of NMDs in adults. We also investigated the effect on fatigue, isometric muscle strength and performance, and perceived ability in targeted functional activities.     

Leg muscle function and fatigue during walking in spinal muscular atrophy type 3

Introduction: Spinal muscular atrophy (SMA) causes muscle weakness and fatigue. Better understanding of the relationship between weakness and fatigue may help identify potential targets for rehabilitation. Methods: Gait and surface electromyography (EMG) from 4 muscle groups were measured during the Six‐Minute Walk Test (6MWT) in 10 ambulatory participants, aged 9–49 years. Average root mean square amplitude (RMS) of muscle activity was calculated. Strength was assessed using manual and quantitative methods. Results: RMS, stride length, and velocity decreased during the 6MWT. Knee flexor and hip abductor strength was associated with fatigue‐related changes; overall strength correlated with disease duration; and leg strength was associated with 6MWT distance. Conclusions: Clinical measures are valid in assessing fatigue and function in SMA, and these assessments can be enhanced by use of gait analysis and EMG. Disease duration and strength measures may represent further stratification refinements when enrolling patients in clinical trials. Muscle Nerve 50 : 34–39, 2014     

Feasibility of foot and ankle strength training in childhood Charcot-Marie-Tooth disease

Weakness of ankle dorsiflexion is the cardinal manifestation of CMT. We investigated if a 12-week progressive resistance dorsiflexion strengthening program was feasible, safe and beneficial in a 15-year-old girl with an axonal form of CMT. Training load was based on a dose-escalating percentage of one-repetition maximum, completed on three non-consecutive days each week. Outcomes included dynamometric foot strength, motor function and instrumented walking ability. At 12-weeks, dorsiflexion strength improved 56–72% and plantarflexion strength by 15–20%. Standing long jump increased by 16%, while balance and endurance did not. Walking ability improved for speed, cadence, step time and stride length. Compliance was high and there were no adverse events. This case suggests progressive strength training might be a feasible intervention to help foot weakness and disability in childhood CMT.     

Clinical relevance of gait research applied to clinical trials in spinal cord injury

The restoration of walking function following SCI is extremely important to consumers and has stimulated a response of new treatments by scientists, the pharmaceutical industry and clinical entrepreneurs. Several of the proposed interventions: (1) the use of functional electrical stimulation (FES) and (2) locomotor training have been examined in clinical trials and recent reviews of the scientific literature. Each of these interventions is based on research of human locomotion. Therefore, the systematic study of walking function and gait in normal individuals and those with injury to the spinal cord has contributed to the identification of the impairments of walking, the development of new treatments and how they will be measured to determine effectiveness. In this context gait research applied to interventions to improve walking function is of high clinical relevance. This research helps identify walking impairments to be corrected and measures of walking function to be utilized as endpoints for clinical trials. The most common impairments following SCI diagnosed by observational gait analysis include inadequate hip extension during stance, persistent plantar flexion and hip/knee flexion during swing and foot placement at heel strike. FES has been employed as one strategy for correcting these impairments based on analysis that range from simple measures of speed, cadence and stride length to more sophisticated systems of three- dimensional video motion analysis and multichannel EMG tracings of integrated walking. A recent review of the entire FES literature identified 36 studies that merit comment and the full range of outcome measures for walking function were used from simple velocity to the video analysis of motion. In addition to measures of walking function developed for FES interventions, the first randomized multicenter clinical trial on locomotor training in subacute SCI was recently published with an extensive review of these measures. In this study outcome measures of motor strength (impairment), balance, Walking Index for SCI (WISCI), speed, 5min walk (walking capacities) and locomotor functional independence measure (L-FIM), a disability measure all showed improvement in walking function based on the strategy of the response of activity based plasticity to step training. Although the scientific basis for this intervention will be covered in other articles in this series, the evolution of clinical outcome measures of walking function continues to be important for the determination of effectiveness in clinical trials.     

A preliminary study on the reliability of physical performance measures in older day-care center clients with dementia

BACKGROUND: Decline in physical functional ability is an intrinsic component of the dementia syndrome. Reductions in muscle mass and strength represent a major factor in the loss of functional ability Although resistance exercise has been studied as a method for maintaining/recovering function in populations of frail older adults, people with dementia have been systematically excluded because of uncertainty about the reliability of outcome measurements. OBJECTIVE: The purpose of this study was to determine the test-retest reliability of a battery of established performance-based measures of strength and function among subjects with dementia. SETTING: A hospital-affiliated adult day-care facility. SUBJECTS: Twelve of 28 older subjects with dementia of various etiologies were available for two assessments prior to implementation of a resistance-exercise intervention. METHODS: Subjects underwent an assessment of lower extremity strength and physical function consisting of two recorded trials of bilateral isometric strength of the knee extensor, hip flexor, and dorsiflexor muscles, as well as hand grip strength; repeated chair stands, evaluation of usual- and maximal safe-gait speed over a 6-m course, and the Timed-Up-and-Go Test. The entire assessment was repeated approximately 1 week later. An average of the trials for each measurement was computed for each of the two assessment periods, and intraclass correlation coefficients (ICCs) for these paired measurements were estimated using STATA. RESULTS: ICCs ranged from .56 for left iliopsoas to .77 for left dorsiflexors among the strength measures whereas measures of function ranged from .80 for number of steps in usual gait to .95 for time of fast gait. CONCLUSIONS: Performance-based measures of strength and function can be reliably assessed in older people with dementia, although measures of function appear to be more reliable than measures of strength.     

Strength and agility training in adolescents with Down syndrome: A randomized controlled trial

The purpose of this study was to investigate the effects of a proposed strength and agility training program of adolescents with Down syndrome. Ninety-two adolescents were recruited and evenly randomized to two intervention groups (exercise group vs. control group). The mean age for the exercise and the control group was 10.6±3.2 and 11.2±3.5 respectively. The exercise training program consisted of a 5-min treadmill exercise and one 20-min virtual-reality based activity administered three times a week for 6 weeks. Pre- and post-test measures were taken for muscle strength and agility performance. The measured muscle included hip extensor, hip flexor, knee extensor, knee flexors, hip abductors, and ankle plantarflexor. A handheld dynamometer was used to measure the lower extremities muscle strength, and agility performance was assessed by the strength and agility subtests of the Bruininks-Oseretsky Test of Motor Proficiency-Second Edition. The exercise group had significant improvements in agility (p=0.02, d=0.80) and muscle strength of all muscle group (all p's<0.05, d=0.51-0.89) assessed in comparison to the control group after the 6-week intervention. Knee muscle groups including both flexors and extensors had the greatest gains among all the muscles measured. A short-term exercise training program used in this study is capable of improving muscle strength and agility performance of adolescents with DS.