Affiliations: Developmental Medicine, Seattle Children's Research
Institute, University of Washington, Seattle, WA, USA | Cardiology, Seattle Children's Hospital, University of
Washington, Seattle, WA, USA | Respiratory Care, Seattle Children's Hospital,
Seattle, WA, USA | Biobehavioral Nursing and Health Systems, School of
Nursing, University of Washington, Seattle, WA, USA | Pediatrics, Seattle Children's Research Institute,
University of Washington, Seattle, WA, USA
Note: [] Corresponding author: Kristie Bjornson, PT, PhD, CW8-6, PO Box
5371, Seattle, WA 98145-5005, USA. Tel.: +1 206 884 2066; Fax: +1 206 884 7801;
E-mail: kristie.bjornson@seattlechildrens.org
Abstract: Introduction: Accuracy and precision of the StepWatch (SW) was
tested in typically developing youth (TDY) with the prediction of oxygen
consumption derived from stride counts. Methods: Ten TDY (5 boys, 5 girls) with an average age 14.1 years
(SD=2.2) enrolled. Participants underwent treadmill cardiopulmonary exercise
testing (CPET) wearing two SW devices at 1, 2, 3, and 4 miles per hour (mph).
Results: Average sign-corrected disagreement for strides counted
between the 2 monitors was 0.4 (0.52), 0.2 (0.42), 0.1 (0.32), and 0.1 (0.32)
for 1, 2, 3, and 4 mph, respectively. The ratio of SW counts to observed manual
counts averaged 100.03% with ICC=0.995. Oxygen consumption equations were
derived from resting and walking VO_{2}, age, gender, and
stride counts. Conclusions: Excellent accuracy and precision was documented for
treadmill walking speeds up to 4 mph while VO_{2} per number
of strides taken appears to decrease with age and is lower in girls.
