This study examined whether the net rate of oxygen uptake (VO2net) and the net oxygen uptake per kilometer (VO2net/km) are affected during walking in adults with Down syndrome (DS) and whether their preferred walking speed (PWS) minimizes the VO2net/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 VO2net and the VO2net/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 VO2net/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.
Stamatis Agiovlasitis is with the Kinesiology and Community Health Department at the University of Illinois in Urbana-Champaign. Jeffrey McCubbin, Joonkoo Yun, and Michael Pavol are with the Nutrition and Exercise Sciences Department at Oregon State University in Corvallis. Jeffrey Widrick is with the Department of Physical Medicine and Rehabilitation at Harvard Medical School in Boston.