Comparison of Self-Paced, Fixed Speed, and Overground Walking Ryan Hartley, Casey Wiens, Molly Schieber, Will Denton, and Vivien Marmelat University of Nebraska at Omaha, Omaha, NE 68182 INTRODUCTION RESULTS Although walking overground is preferred, treadmills are widely used in lab settings due to space limitations. Because treadmills are set at a fixed speed, they constrain subjects to walk differently than while overground.1 To help alleviate this constraint, an algorithm has been developed that allows the treadmill to change speed according to the subject’s movement. Purpose: To compare self-paced, fixed speed, and overground walking. Hypothesis: The walking patterns of the subjects during self-paced walking will be different from fixed speed conditions and more similar to overground walking. Figure 1. Stride-time intervals across conditions. Figure 2. Coefficient of variation across conditions Figure 3. DFA on stride-time intervals across conditions. DISCUSSION Self-paced treadmill walking seems more stable than fixed speed treadmill walking, as suggested by similar CV for both conditions. However, stride-time dynamics on the self-paced treadmill indicates more similarity to overground walking. Further analysis will be conducted on stride length and stride speed as well. METHODS 4 healthy young (Age 19-23) completed three 15 minute walking conditions: self-paced, fixed speed, and overground. A 5 minute warm-up was completed before each 15 minute trial. Inertial Measurement Units (IMUs) were worn on the right leg to record acceleration data.2 The Trail Making Test Part A&B was performed between trials as a cognitive wash.3 Stride-to-stride dynamics were estimated using the Detrended Fluctuation Analysis (DFA). The average and the coefficient of variation (CV) of stride-time intervals were also analyzed. CONCLUSIONS If confirmed, these results would suggest self-paced treadmill walking as a better approximation of overground walking than fixed speed. REFERENCES Alton F, et al. Clin Biomech. 1998;13(6):434-440. Dai H, et al. BioMedical Engineering OnLine. 2015;14(1):1-13. Tombaugh TN. Archives of Clinical Neuropsychology. 2004;19(2):203. Table 1. Testing protocol Adaptation SPTM 5 minutes Trial 1 15 minutes (Random) Cognitive Wash Preferred Walking Speed Trial 2 Fixed Speed Trial 3 Overground This work was supported by the Center for Research in Human Movement Variability of University of Nebraska at Omaha, NIH (P20GM109090), and by the University Committee on Research and Creative Activity of the University of Nebraska at Omaha.