?HABITUAL PHYSICAL ACTIVITY AND HEART RATE LEVEL OF CHILDREN WITH DOWN'S SYNDROME

Abstract

Very low rate of gross bodily activities are observed more frequently in children with Down's syndrome than in nonretarded children. This study was designed to observe the characteristics of habitual physical activity of children with Down's syndrome. Five Down's syndrome boys, ranged in ages from 8 to 15 years, and their IQ scores ranged from 34 to 44, were selected as the experimental subjects. The comparison group consisted of 6 mentally subnormal boys with IQs ranging from 45 to 68. Their ages ranged from 9 to 15 years. Both group of subjects were selected from the same school and residence for mentally retarded children. Two types of observation were simultaneously undertaken in a day from 7:00 am to 7:00 pm. One observation was on thier action type, and the other was on its heart rate level which is widly accepted as an index of energy expenditure level. Each activity directly observed was classified into seven types of action such as, 1) running 2) walking 3) standing 4) sitting on the chair 5) sitting down 6) sitting on the floor and 7) lying on the floor. In "running" and "walking", the Down's group showed them significantly less often than the control group (U test, P<0.05). In the free ranging situation, they tended to spend much time in indoor space sitting on the floor compared with the control group (U test, P<0.05). The hypoactive tendency was also observed in the results of heart rate variation profile. Heart rate, transmitted from the subject via a telemetric system, was continously counted every two minutes and the Down's group showed little periodic change in heart rate level throughout the day. Mode value on the heart rate distribution curve was 76 beats/min. in Down's syndrome and 98 beats/min. in control group. Four of six control subjects showed strong motor activity in which heart rate level exceeded 180 beats/min., but no one in Down's group experienced. The results were disscussed in relation to brain-injured symptoms, respiro-circulatory defects, hypotonia of muscle and over-protection in nurture.