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Performance of Retarded Children, With and Without Down Syndrome, on the Bruininks Oseretsky Test of Motor Proficiency
BARBARA H. CONNOLLY and BETH T. MICHAEL
The purpose of this study was to examine the gross motor and fine motor abilities of children with mental retardation using the Bruininks Oseretsky Test of Motor Proficiency. We compared the motor skills of 24 mentally retarded children, 12 with Down syndrome and 12 without Down syndrome. The children ranged in chronological age from 7.6 years to 11 years and were of comparable mental age. Within each group, there were no significant sex differences nor were there differences between the two groups in motor performance for the male subjects. The female subjects with Down syndrome, however, scored significantly lower than female subjects without Down syndrome on running speed, strength, visual motor ability, speed, and dexterity and fine motor composite scores. As a group, the children with Down syndrome scored significantly lower than the children without Down syndrome in the areas of running speed, balance, strength, and visual motor control. The gross motor and fine motor skill composite scores were also significantly lower for the children with Down syndrome than for the children without Down syndrome.
Key Words: Child development, Downs syndrome, Mental retardation, Motor skills.
Physical therapists have long been interested in the assessment of fine motor and gross motor skills of the mentally retarded child. From infancy, the child with mental retardation may have motor development that progresses at a slower rate than that expected for a child with average intelligence. Parents who are sensitive to the development of their child may detect the delay in motor skill acquisition before becoming aware of the cognitive delays.
According to Malpass, the sequence of motor development in children who are classified as trainably mentally retarded (TMR) approximates that of children of average intelligence whose gross motor skills continue to develop until they are 16 years of age.1 The TMR
child, however, shows a delay in the rate of acquisition of those skills. The degree of the delay depends on the type of skill. The child usually has difficulty with coordination and exhibits less manipulative dexterity than children of average intelligence of the same age and sex.1
Most TMR children show some form of central nervous system dysfunction that leads one to expect problems involving coordination, gait, and fine motor abilities.2 In general, studies indicate that the mean scores of motor skill proficiency of mentally retarded children are inferior to the mean scores of children with average intelligence quotients (IQs).3,4
Groden reported substantial relationships between IQs and motor skill proficiency.5 Even when the influence of purely motor disabilities (eg, finger tapping and grip tests) was controlled, a perceptual motor task in which the subjects quickly and consecutively pressed four buttons arranged in a square showed a significant relationship between motor skill proficiency and IQ.5
Trainably mentally retarded children without any specific motor skill disabilities, therefore, may show deficiencies in performing complex motor skill tasks. Groden's research also indicated that mentally retarded children not only
have much less strength than children with average IQs but become fatigued more quickly.5 Hayden also found that mentally retarded children are only half as strong physically as their nonretarded peers.6 In contrast, another study revealed that children who were moderately retarded performed as well as their nonretarded peers on a strength and grip test.7 These same moderately retarded children, however, performed much more poorly than their nonretarded peers on tests of hand steadiness, eye-hand coordination, dexterity, and responsiveness. Slow reaction times to test items have been reported by various researchers.7,8
Within the population of mentally retarded children, the gross motor skills of the child with Down syndrome have been studied closely. The rate of motor development of children with Down syndrome is slightly below that of non-Down syndrome children.9-11 During the first 6 months of life, the motor skill development of infants with Down syndrome closely parallels that of non-Down syndrome infants, although infants with Down syndrome develop at a slightly slower rate. By the age of 12 months, however, the motor skill development of the child with Down syndrome often is 4 to 5 months behind
Dr. Connolly is Associate Professor, Department of Rehabilitation Sciences, Program in Physical Therapy, The University of Tennessee Center for the Health Sciences, 800 Madison Ave, Memphis, TN 38163 (USA).
Ms. Michael is Instructor, Department of Rehabilitation Sciences, Program in Physical Therapy, The University of Tennessee Center for the Health Sciences and Acting Chief, Child Development Center, The University of Tennessee Center for the Health Sciences.
This study was supported in part by US Public Health Service Grants MCT-002041-01 and MCT-900.
This article was submitted March 12, 1985; was with the authors for revision eight weeks; and was accepted August 6, 1985.
344 PHYSICAL THERAPY
RESEARCH
that of the 1-year-old child without Down syndrome. At the age of 5 years, the motor skill development of the child with Down syndrome is approximately two years behind that of the child without Down syndrome, and he performs many activities at 50% to 70% below the normal rate.12,13 Share reported that none of the 212 children with Down syndrome under 7 years of age in his study could perform such motor tasks as buttoning a shirt or riding a tricycle.14
Interestingly, it has been suggested that female performance is superior to that of male performance on motor skill tasks.15,16
Several studies have demonstrated that children with Down syndrome generally have deficits in eye-hand coordination, laterality, and visual motor control.17-22 Reaction times also have been shown to be slower in children with Down syndrome when compared with reaction times of other children with mental retardation.23,24 Poor balance also has been cited as a deficit.25 Poor muscle tone, awkwardness of movement, flabby hands, and short fingers have been reported as causes of these delayed skills.26
In a recent study by Connolly et al, the gross motor and fine motor skills of a group of children with Down syndrome were evaluated using the Bruin-inks Oseretsky Test of Motor Proficiency.27 That study showed that fine motor skills requiring eye-hand coordination, laterality, and visual motor control were among the most advanced in these children. In ranked scores on the Bruininks Oseretsky subtests, the highest scores were obtained on upper limb coordination. The children encountered some difficulties in the subtests requiring balance. Hypotonia and the effects of hypotonia, such as decreased pelvic stability and pes planus, were thought to contribute to balance problems seen in activities involving one-foot standing, tandem walking, and running.
The only gross motor skill subtest category that ranked in the top scores was strength. Connolly et al postulated that these items—push-ups, sit-ups, and broad jumps—all were components of physical education programs and that the scores on the strength test might reflect practice effects.27
Although there is general agreement that children with Down syndrome perform below average in fine motor and gross motor skills, the discrepancy be-
TABLE1 Representation of Subject Classification by Age, Sex, and Intelligence Quotient
Subjects
Mean chronological age (yr) Chronological age range (yr) Mean IQ IQ range Boys Girls
Down Syndrome
9.16a
7.6-10.5 54.5b
38-69 3 9
Non-Down Syndrome
9.25a
7.9-11.0 56.8b
42-66 7 5
tween the motor skills of the child with Down syndrome and those of the mentally retarded child without Down syndrome has been disputed.28 Some investigations between matched groups of mentally retarded children, one group with and one group without Down syndrome, found no significant differences between the motor skills of children with Down syndrome and those of children without Down syndrome.7,25, 29 The children with Down syndrome actually performed some motor skill tasks superiorly.25 Henderson et al, however, found that children with Down syndrome performed tasks more slowly and had more difficulty with balance tests than did children who were mentally retarded but without Down syndrome.21
Sixty-four percent of the mentally retarded children without Down syndrome, for example, could maintain their balance on one foot for longer than four seconds, but only 35% of the children with Down syndrome could do the task.21 Other studies suggest that if the children with Down syndrome understand the task and are of comparable mental age, they have motor skills equal to mentally retarded children without Down syndrome.7,30,31
The purpose of this study was to examine the gross motor and fine motor abilities of children with mental retardation using the Bruininks Oseretsky Test of Motor Proficiency. We compared the motor skills of mentally retarded children with Down syndrome with those of mentally retarded children without Down syndrome and addressed the following questions:
1. Do significant differences exist between the gross motor skills of mentally retarded children with Down syndrome and those of mentally retarded children without Down syndrome as tested by the Bruininks Oseretsky Test of Motor Proficiency?
2. Do significant differences exist between the fine motor skills of mentally retarded children with Down syndrome and those of mentally retarded children without Down syndrome as tested by the Bruininks Oseretsky Test of Motor Proficiency?
3. Do significant differences exist between the gross motor and fine motor skill levels of male subjects and those of female subjects as tested by the Bruininks Oseretsky Test of Motor Proficiency?
METHOD
Subjects We performed motor proficiency test
ing on 24 children who had been tested previously using the Stanford-Binet Intelligence Scale and who had been diagnosed by a psychologist as being mentally retarded. Twelve of the children had been diagnosed as having Down syndrome. The other 12 children were diagnosed as being mentally retarded but without any type of neuromotor dysfunction or genetic defect. None of the children were enrolled in physical therapy programs at the time of the study.
The children with Down syndrome ranged in age from 7 years 7 months to 10 years 6 months ( = 9 years 2 months, s = 13.1 months). The children without Down syndrome ranged in age from 7 years 11 months to 11 years ( = 9 years 3 months, s = 10.2 months). The children with Down syndrome had IQs ranging from 38 to 69 ( = 54,5, s = 9.64). The children without Down syndrome had IQs ranging from 42 to 66 ( = 56.8, s = 9.06). The t-test analyses of both chronological age and IQs yielded no significant differences between the two groups. Table 1 describes the children involved in the study by age, IQ, and sex.
a Not significant at t = .313, df = 22. b Not significant at t = .610, df = 22.
Volume 66 / Number 3, March 1986 345
TABLE 2 Summary of Median Developmental Ages and Range of Developmental Ages for Gross Motor and Fine Motor Skills
Skillsa
Running speedb
median range
Balancec
median range
Bilateral coordination median range
Strengthc
median range
Gross motor skill compositec
median range
Upper limb coordination median range
Response time median range
Visual motor skill controlc
median range
Upper limb speed and dexterity median range
Fine motor skill composite0
median range
Down Syndrome (yr-mo)
4-2 below 4-2 to 5-5
4-3.5 below 4-2 to 5-5
5-2 below 4-2 to 7-11
5-11 4-2 to 8-2
4-8.8 below 4-2 to 6-0
5-11 4-2 to 9-2
below 4-2 below 4-2 to 6-11
4-5 below 4-2 to 7-11
5-5 4-2 to 6-5
4-3.5 below 4-2 to 6-2
(n)
(12)
(12)
(12)
(12)
(12)
(12)
(8)
(12)
(12)
(12)
Non-Down Syndrome (yr-mo)
6-0.5 4-2 to 8-11
5-2 below 4-2 to 10-2
6-5 below 4-2 to 7-11
7-3.5 4-11 to 10-8
6-6.3 below 4-2 to 8-5
5-7.5 below 4-2 to 8-5
5-3.5 below 4-2 to 7-11
6-0 below 4-2 to 10-2
5-9.5 4-2 to 7-5
6-0 below 4-2 to 7-2
(n)
(12)
(12)
(12)
(12)
(12)
(12)
(12)
(12)
(12)
(12)
All of the children attended special education classes in a large metropolitan city in the South. A signed informed consent was obtained from the parents of each child before testing of the child was performed.
Tests
The Bruininks Oseretsky Test of Motor Proficiency (long form) was administered to each of the children. The Bruininks Oseretsky test includes subtests in running speed, balance, bilateral coordination of the arms and legs, strength, upper limb coordination, response time, visual motor control, and speed and dexterity of the upper extremities. The Bruininks Oseretsky Test of Motor Proficiency, a standardized test, yields age levels for each of the individual subtests, a gross motor skills composite age, and a fine motor skills composite age. The test is standardized for
children between the ages of 4 years, 2 months and 16 years. If a child scores below the basal age of the test, 4 years, 2 months, he is assigned a score of below 4 years, 2 months.
Procedures
Each child was assessed individually by one of us. The order of the testing of the children was random and not according to developmental or chronological age. A total of 1.5 to 2 hours was spent with each child in obtaining the data. Standardized procedures were used according to the test manual for the Bruininks Oseretsky Test of Motor Proficiency. Interrater reliability for administration of the test in accordance with the standardized procedures has been reported as between .90 and .98 even when the rater has had no formal training in the scoring.32
Data Analysis
Descriptive statistics were used to describe the characteristics of the children involved in the study. Statistical analysis of the data on age and intellectual functioning of the children included the t test for differences between the means of two groups. Statistical analysis of the data obtained with the Bruininks Oseretsky Test of Motor Proficiency was performed using the Mann-Whitney U rank sum test because the scores had to be ranked as a result of noninterval data (eg, below 4 years, 2 months). The level of significance used throughout the study was p = .05; however, if a level of significance was found to be greater than .05, that level was reported in the finding.
RESULTS
The results of the Bruininks Oseretsky Test of Motor Proficiency revealed varying degrees of differences on the individual subtests. The median scores for each subtest for the two groups and the range of scores are shown in Table 2. Analysis of the individual subtests between the two groups using the Mann-Whitney U test yielded significant differences between the two groups in the areas of running speed, balance, strength, and visual motor control with the children without Down syndrome scoring significantly higher than the children with Down syndrome. The two groups also had significantly different gross motor and fine motor skill composite scores, again with the children without Down syndrome scoring significantly higher than the children with Down syndrome.
When we compared the scores on the individual subtests within groups by sex, we found that the scores of the boys and girls with Down syndrome were not significantly different. We also found that the scores of the boys and girls without Down syndrome were not significantly different.
The scores of the girls with Down syndrome (n = 9) were significantly higher than the scores of the girls without Down syndrome (n = 5), however, in the areas of running speed, strength, visual motor control, and upper limb speed and dexterity and in their fine motor skill composite scores. We noted no significant differences between the scores of the boys with Down syndrome (n = 3) and the scores of the boys with-
a Bruininks Oseretsky Test of Motor Proficiency. bp<.005. cp<.05.
346 PHYSICAL THERAPY
RESEARCH
out Down syndrome (n = 7) on any of the subtests or motor skill composites.
As a part of the Bruininks Oseretsky test, we determined arm preference. In our sample, 10 children were right-handed, 8 were left-handed, and 6 were ambidextrous. Our sample represents a greater number of left-handed children than we would expect to find in a comparable sample of nonretarded children. Fagan-Dubin, in a study of 1,257 non-retarded children, found 11.4% to be left-handed, as compared with the 33.3% found in our study.33 We found no significant difference in handedness between the children with Down syndrome and those without Down syndrome when a chi-square analysis was performed.
DISCUSSION
The results of our study indicate that significant differences in gross motor skills and fine motor skills exist between mentally retarded children with Down syndrome and mentally retarded children without Down syndrome. As indicated by the results of the Bruininks Oseretsky subtests, differences were noted in the areas of running speed, balance, strength, visual motor skill control, and overall gross motor and fine motor skill performance. In our study, the group of children with Down syndrome and the group of children without Down syndrome were of comparable mental age. The results of our study, therefore, do not support the results of earlier studies reporting that children with Down syndrome have skills comparable to those of retarded children of the same mental age without Down syn-drome.7,25,29-31 Henderson et al21 and Nakamura25 have reported that children with Down syndrome have more difficulty with 'balance tasks than children with mental retardation but without Down syndrome. Their findings are supported by the findings of our study because we found balance to be significantly different between the two groups. The neuropathology associated with Down syndrome includes delayed cerebellar maturation and a relatively small cerebellum and brain stem.34 Thus, the clinical finding of balance and coordination problems in the child with Down syndrome may be related to neuropatho l o g y causes.
We did not detect the slower reaction times others found in their studies of children with Down syndrome.23,24 Al
though we did not find any significant difference between the two groups on the response speed subtest, only 8 of the 12 children with Down syndrome were able to perform this particular subtest.
Strength has been reported as being an area of deficit in all children with mental retardation.6 We noted a significant difference between the children with Down syndrome and those without Down syndrome. Both groups, however, performed at greater than one-half the strength of their nonretarded peers, in contrast to the findings of Hayden.6
We found significant differences between the two groups in the area of visual motor skill control and in overall fine motor skill performance with the children without Down syndrome scoring higher. These results support previous studies that reported deficits in eye-hand coordination and visual motor skill control for children with Down syndrome.17"22 The children with Down syndrome, however, did not differ significantly on the subtest of upper limb speed and dexterity, in contrast to the findings reported by Knights et al.7
Although we used small numbers of children in the analysis of sex differences, the results revealed no significant differences between the performances of boys and girls with Down syndrome, nor between the performances of boys and girls without Down syndrome. Studies that had reported the superiority of girls with Down syndrome over boys with Down syndrome in the performance of motor skill tasks are not supported by our findings.1516 In fact, when we compared girls with Down syndrome with girls without Down syndrome, we noted significantly poorer performance in the areas of running speed, balance, strength, visual motor skill control, and upper limb speed and dexterity and in fine motor skill composite scores for the girls with Down syndrome. When we compared boys with Down syndrome to boys without Down syndrome, however, we found no significant differences. Thus, the lower scores of the girls with Down syndrome appear to provide the basis for the differences between the two groups as a whole.
In both groups of children in this study, we noted a higher incidence of left-handedness than we would expect in a sample of nonretarded children. Other researchers have reported that children with mental retardation have a
higher incidence of left-handedness, and this was the finding of our studv.35-37
Although we do not attempt to delineate the causes of the differences between the two groups in our study, the findings are of clinical relevance to physical therapists. The areas in which the children with Down syndrome performed poorly—running speed, balance, strength, and visual motor skill control—suggest that the child with Down syndrome may continue to have neurological problems far beyond the preschool period and into adolescence. Currently, the majority of physical therapy available to the child with Down syndrome is provided during the preschool years and not after the child enters a regular school program. If the child with Down syndrome does receive structured physical education programming, the activities are of a general nature, and the child is treated in a group setting instead of receiving individualized programming. Our study has shown that differences in the gross motor and fine motor skills exist between the mentally retarded child with Down syndrome and the mentally retarded child without Down syndrome. Therefore, the child with Down syndrome may continue to need individualized physical therapy as a part of his special education programming to address his particular motor skill needs. The neuropathology associated with Down syndrome, particularly as related to the small size of the cerebellum and the brain stem, suggests that children with Down syndrome may experience problems with balance and coordination. This finding strongly supports our supposition that individualized physical therapy may be appropriate for children with Down syndrome not only during their preschool years but throughout their adolescence.
CONCLUSION
The results of our study indicate that children with Down syndrome perform poorly in the areas of running speed, balance, strength, and visual motor skill control and in overall gross motor and fine motor skills in comparison with mentally retarded children without Down syndrome but of comparable chronological and mental ages. Although our study addressed specific questions regarding motor functioning in children with Down syndrome in
Volume 66 / Number 3, March 1986 347
comparison with mentally retarded children without Down syndrome, more research is needed on a larger sample of children. We found significant differences between the girls with Down syndrome and those without Down syndrome; the non-Down syndrome girls scored higher. We were unable to detect any significant differences, however, between boys with Down syndrome and those without Down syndrome. The number of children in this analysis was small and a larger sample size should be used in any future research in this area.
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