Recovery from perturbations during paced walking

Postural stability when walking: Effect of the frequency and magnitude of lateral oscillatory motion

“…11). The increase in peak-to-peak COP position indicates an increase in step width, which is adjusted to compensate for lateral acceleration induced by external perturbations (e.g., Oddsson et al, 2004;Brady et al, 2009). The increase in lateral r.m.s.…”

“…To compensate for medio-lateral acceleration induced by perturbations, it has been suggested that the central nervous system adjusts the step width to alter the moment arm (Oddsson et al, 2004). Although the main strategy for maintaining balance is the 'stepping strategy', large errors in foot placement are corrected by hip moments (Hof et al, 2007;McKinnon and Winter 1993) and fine tuning is achieved by active ankle moments.…”

“…Sudden accelerations or decelerations of a treadmill (Berger et al, 1984) or a moveable platform embedded in a walkway (e.g., Nashner, 1980;Oddsson et al, 2004;Bhatt et al, 2005) have been used to investigate responses to slips, trips, and missteps encountered during walking. Longer duration low frequency oscillations (0.2 to 0.5 Hz) of a treadmill on a six-axis motion platform (e.g., Brady et al, 2009;McAndrew et al, 2010) have been used to investigate postural responses to perturbations when walking but have not been representative of motions encountered in transport.…”

“…(Owings and Grabiner, 2004). It has been suggested that step width is adjusted to compensate for lateral acceleration induced by external perturbation (Oddsson et al, 2004).…”

Foot placement in balance recovery

“…Literature provides a massive range of perturbation experiments. These include perturbations applied to the stance leg(s) through support surface translations (Maki et al, 1996;Oddsson et al, 2004;Brady et al, 2009;Hak et al, 2013;Sari and Griffin, 2014), rotations (Rouse et al, 2014), and elevations (Nashner et al, 1979;Af Klint et al, 2009), through loss of support surface area (Horak and Nashner, 1986;Otten, 1999) and loss of support surface friction (Pai and Iqbal, 1999;Cham and Redfern, 2002), through perturbations applied to the swing leg (Cordero et al, 2003;Pijnappels et al, 2005;Rankin et al, 2014), to the pelvis Qiao and Jindrich, 2014), to the shoulders (Engelhart et al, 2015), and to the head (Horak et al, 1994), through sudden release of a supporting force (Do et al, 1982;Hsiao-Wecksler, 2008), and through sensory disturbances (Hayashi et al, 1981;Fitzpatrick et al, 1994), just to name a few, see Figure 3. On top of all the possible ways to apply a perturbation, other factors such as the magnitude and direction (Maki et al, 1996) of the perturbation, the subject's expectations about the perturbation (Bhatt et al, 2006), the instruction to the subject (Do et al, 1999), as well as the subject characteristics (healthy, impaired, young, elderly) can affect the observed balance recovery response.…”