Economy and Preferred Speed of Walking in Adults With and Without Down Syndrome

This study examined whether the net rate of oxygen uptake (VO(2net)) and the net oxygen uptake per kilometer (VO(2net)/km) are affected during walking in adults with Down syndrome (DS) and whether their preferred walking speed (PWS) minimizes the VO(2net)/km. Respiratory gases were collected as 14 adults with DS and 15 adults without DS completed a series of treadmill walking trials. PWS was measured over 15 meters in a hallway. The VO(2net) and the VO(2net)/km were higher in adults with DS than adults without DS. The overground PWS normalized for leg length was the same for both groups and did not appear to minimize the VO(2net)/km. Thus, adults with DS are less economical during walking than adults without DS. The overground PWS does not minimize the metabolic cost during treadmill walking.