Methods for Quantifying the Variability in Time-series Data

Using a treadmill to monitor locomotion is extremely convenient for sport and exercise research (Nigg et al., 1995). A problem exists if kinematic, kinetic, and metabolic or other variables, for example, are not uniform between treadmill and overground locomotion. As Nigg et al. (1995) suggested discussion about the degree of similarity between overground and treadmill running is inconsistent throughout the literature. For example, Schache et al. (2001), in their study of the three-dimensional kinematics of the lumbopelvic-hip complex, found subtle but significant differences in the sagittal plane movement of the hip joint. However, Williams (1985) concluded that the only significant differences in kinematics present between overground and treadmill running were at speeds greater than 5 m.s.