This research is a prospective cohort study. Participants included boys with ID studying at Golestan Institution in the academic year (2020–2021). After obtaining permission from the Department of Education and making necessary arrangements, personal information and medical records of the subjects were collected using the files of children with ID. In this study, active children with ID were those who had regular physical activity for three sessions a week (36 sessions, one-hour physical activity in moderate intensity) under the supervision of a coach for 3 months before COVID-19 restrictions, and inactive individuals had no regular physical activity schedule before and after the restrictions.
The physical activity level was defined in-self-report according to the WHO physical activity guidelines during the COVID-19 pandemic that the movement restriction was determined by not having moderate-vigorous regular physical activity (i.e., walking and running) for 30 min to an hour even 1 day a week. Inclusion criteria included not participating in regular physical activity during the past year according to parents’ reports, taking neuroleptics or medicines affecting balance, having no history of lower limb injury and surgery during the past year, having no disease in the atrial system, and no cochlear implantation, no visual impairment, having a normal vision without glasses, willingness and ability to participate in the test, and parental informed consent to participate in the study. Exclusion criteria included ankle injuries, lower limb and spine surgeries during the past year, a history of neuromusculoskeletal diseases, severe hearing and vision problems, taking neuroleptics, and a history of lower limb injury and surgery. Then, written informed consent was obtained from the subjects’ parents for participation in the study (Fig. 1).
To determine the sample size, G*POWER statistical software was used with test power (0.80), effect size (0.50), and significance level (0.05)8, 15. The required number of samples was determined to be 30. Then, from among 50 educable boys with an age range of 6 to 13 years and an IQ between 50 and 75 based on the inclusion and exclusion criteria, 30 individuals were randomly selected through a purposeful and convenience sampling method and were randomly divided into two groups of active and inactive individuals.
Subjects were normalized in terms of age, height, weight, and Body Mass Index (BMI) in the desired groups. Subjects were evaluated in the pre-test regarding postural control, functional balance, dynamic balance, and motor skills using the BESS test, the Y test, the Timed Up and Go (TUG) test, and the Bruininks-Oseretsky test-short version in two stages, once in September 2020 and then a year later in 2021. The tests were taken by 2 researchers of this study in the indoor sports hall under the supervision of school authorities. All participants were evaluated during all research stages in terms of health protocols related to Covid-19.
Postural control evaluation
The BESS test was used to measure static postural control with 75% validity and 50–82% reliability [25, 26]. The static balance test was performed in three positions: Standing position, including two legs next to each other, standing on one leg (the superior leg and the non-superior leg), and tandem standing position (standing with trailing leg, 1 foot forward, and one leg back). The superior leg was determined to measure balance tests by the tendency to shoot a soccer ball . The hands were on the waist in all three positions, and the test was performed with the eyes closed. All three positions were performed on two hard (ground) and soft (foam) surfaces for 20 seconds for each position. The test time was recorded by a timer immediately after the subject’s eyes were closed. When performing the test in each position, six types of errors, if made, were counted and recorded for each subject. These errors included removing the hands from the waist, opening the eyes, stepping or falling, raising the heel or toe, flexing the torso forward or sideway more than 30 degrees, and deviating from the defined position, which was repeated for each position for 5 seconds and each test three times [28, 29].
Dynamic balance measurement
To evaluate dynamic balance, the Y balance test with 91% validity and 84% reliability was used [30, 31]. In this test, three directions (anterior, posterior-external, and posterior-internal) were drawn at an angle of 135 degrees from each other. Since this test has a significant relationship with length, to perform it and normalize the real information of the foot, the upper anterior iliac spine to the inner ankle was measured in a supine position to lying down on the floor . Each subject practiced the test six times to learn how to perform it. The subject stood on 1 foot in the center of the sitting area with the other foot in the direction chosen by the examiner, performed the maximum achievement action without error, and returned to the original position. To eliminate the learning effect, each subject practiced each direction six times, each time with a 15-second rest. After a five-minute rest, the subject began the test in the direction randomly chosen by the examiner, and the examiner measured the contact point of the person’s foot to the center of the toe in centimeters. The test was repeated three times for each subject, and the best record was divided by the leg length and then multiplied by 100 to obtain the achievement distance in terms of the leg length percentage. In the event of an error with the foot in the center, the test was repeated. The subject performed each direction three times, and the mean of three attempts was considered as the dynamic balance score .
Functional balance evaluation
The TUG test was used for this purpose. A chair without a handle, a stopwatch, and a three-meter distance was required to perform this test. The three-meter path started from the legs of the chair. The subject, sitting in his usual shoes and clothes, sat on a chair and leaned on the chair back. At the command of the examiner, the subject got up and walked the marked three-meter distance. After arriving at the end, he turned around and sat down on his chair. In total, he walked six meters. The duration of the test was recorded as the individual’s score in seconds, and it is worth noting that the record of this test was the mean of performing it three times, and its validity and reliability were reported as 91 and 99%, respectively . Individuals whose time in the test was less than 20 seconds were considered to have good independent movement .
The Bruininks-Oseretsky test evaluation
The Bruininks-Oseretsky test of Motor Proficiency, 2nd ed. (BOT-2) is a set of tests specific for children aged 4.5–14.5 years that assesses gross and fine motor skills to identify their motor proficiency and motor disorder . Based on the test instructions, preparation of testing conditions needs 10 minutes and Implementation of the full form takes 40–60 minutes. The BOT-2 examines 53 items in four motor area composites. Fine Manual Control (15 Items), which covers motor skills including control and coordination of the distal musculature of the hands and fingers; Manual Coordination (12 Items), coordination of the arms and hands, especially for object manipulation; Body Coordination (16 Items), coordination of the large musculature used in maintaining posture and balance; and Strength and Agility (10 Items), which consists of aspects of fitness and coordination involved in casual play, competitive sports, and other physical activity . The raw score of each item is recorded in the unit measured (e.g. seconds, number of catches) and then converted into a numerical score . In this study, the Bruininks-Oseretsky test was used to assess the gross and fine motor skills involving eight components including running speed and agility, balance, mutual coordination, strength, response speed, visual-motor control, and upper limb speed and agility in children with ID with developmental coordination disorders. These components measure four subscales of gross motor skills, three subscales of fine motor skills, and one subscale of both gross and fine motor skills . This test has the necessary validity and reliability so that the validity coefficient of the Bruininks-Oseretsky test scores in the assessment of motor skills has been equal to 90%. The retest reliability coefficient of this collection has been reported to be 0.78 in the full form and 0.86 in its short form. The short-form version measures children’s motor skills in general, and the total score indicates children’s general skills, including gross and fine skills . The short form of the test was used in this research.
The Shapiro-Wilk test was used to check the normality of data, and the Paired-Samples T-Test, Wilcoxon Signed Ranks Test, analysis of covariance (ANCOVA), and Mann–Whitney U was used to analyze the pre-test and post-test results at a significance level of p < 0.01in SPSS version 21 software.