Physiological Measures During Treadmill Testing in Youth With Down Syndrome

Presently many researchers are objectively measuring physical activity via accelerometry. Accelerometers produce unitless data counts and are coupled with physiological information related to intensity of physical activity. Many of these physiological criteria are based on well-established exercise responses derived from typically developed populations.

Background/Purpose Examine the physiological responses to physical activity in youth with and without Down syndrome (DS) during a submaximal treadmill task.

Method Fifty-three participants (27 DS; 26 control) between the ages of 9-18 years participated in a graded-submaximal treadmill task. Participants walked at 2.5 miles per hour and every three minutes the incline increased 2.5 degrees. Respiratory gases along with heart rate were collected on a breath by breath basis.

Analysis/Results All participants engaged in identical protocols. Participants with Down syndrome were found to have lower peak VO2 values (p < 0.01) and lower peak VO2 values corrected for lean body mass (p < 0.05). Participants with Down syndrome also performed at a higher level of their maximum percent heart rate (p < 0.01) and had greater peak respiratory exchange ratios (p < 0.01).

Conclusions There is physiological evidence participants with Down syndrome experienced the task differently although both groups were given identical tasks. Participants with Down syndrome were exerting themselves more to complete the task compared to their peers. Applying information derived from typically developed individuals is likely to result in invalid data. With an increased interest in objectively measuring physical activity it is necessary to understand the unique physiological responses to physical activity in this population.