Limits...
Age-Related Differences in Stepping Response When Stepping onto a Known Soft Surface under Dual Task Conditions.

Harada N, Okada S, Negoro S - Curr Gerontol Geriatr Res (2010)

Bottom Line: For the second experiment, they stepped on a soft surface placed in front of them while performing the above tasks.The main result was that %DIP (initiation phase as a percentage of the total stepping task time) was significantly higher for older than for young adults during the dual task on the soft surface.In conclusion, caution due to previous experience may increase attentional demand during dual tasks and lengthen the time required for central nervous processing in order to avoid losing postural stability in older adults, resulting in reductions in step velocity and step length compared to those in young adults.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Human Development and Environment, Kobe University, 3-11 Tsurukabuto, Nada-ku, Kobe 657-8501, Japan.

ABSTRACT
The purpose of this study was to investigate whether age-related differences in stepping response influence postural control when stepping onto a known soft surface under dual task conditions. Nine young and eleven older female adults participated. First, they stepped on a flat surface while grasping an empty cup (single task), and then they repeated the task while grasping a cup filled with water (dual task). For the second experiment, they stepped on a soft surface placed in front of them while performing the above tasks. The main result was that %DIP (initiation phase as a percentage of the total stepping task time) was significantly higher for older than for young adults during the dual task on the soft surface. In conclusion, caution due to previous experience may increase attentional demand during dual tasks and lengthen the time required for central nervous processing in order to avoid losing postural stability in older adults, resulting in reductions in step velocity and step length compared to those in young adults.

No MeSH data available.


An example of step response data. From top to bottom: Tap cue on back of heel; COPx = Mediolateral center of pressure; Fx =  Ground reaction force in lateral direction; Fy = Ground reaction force in anteroposterior direction; Fz = Vertical ground reaction force. The stepping task was divided into four phases: (1) the initiation phase (I) was calculated from the tap cue to the onset (OT); (2) the preparatory phase (P) was calculated from OT to foot-off for the right leg (rFO); (3) the swing phase (S) was calculated from rFO to foot-contact for the right leg (rFC); (4) the double-stance  stance phase (D) was calculated from rFC to foot-off for the left leg (lFO).
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2877204&req=5

fig1: An example of step response data. From top to bottom: Tap cue on back of heel; COPx = Mediolateral center of pressure; Fx = Ground reaction force in lateral direction; Fy = Ground reaction force in anteroposterior direction; Fz = Vertical ground reaction force. The stepping task was divided into four phases: (1) the initiation phase (I) was calculated from the tap cue to the onset (OT); (2) the preparatory phase (P) was calculated from OT to foot-off for the right leg (rFO); (3) the swing phase (S) was calculated from rFO to foot-contact for the right leg (rFC); (4) the double-stance stance phase (D) was calculated from rFC to foot-off for the left leg (lFO).

Mentions: The method for the data analysis of the present study was taken from Brauer et al. [14] and Melzer and Oddsson [15]. The COPx (Mediolateral center of pressure) and the ground reaction force data (Fx = ground reaction force in lateral direction; Fy = ground reaction force in anterior-posterior direction; Fz = vertical ground reaction force) have been described in terms of the length of events during the stepping task (Figure 1); onset time (OT) was determined as the first medio-lateral shift of the COPx (COPx excursion greater than 10 mm away from the baseline following the tap). Time of foot-off for the right limb (rFO) was determined from the trace of Fy, the first lowest peak value at approximately the same time as the trace of Fz and the first highest peak value following OT. The second peak value of the vertical force (Fz) was used to determine the time of foot-contact (rFC), and it was nearly equivalent to the second lowest peak value of Fy. The time of foot-off for left limb (lFO) was determined when the trace of COPx reached its final stable value.


Age-Related Differences in Stepping Response When Stepping onto a Known Soft Surface under Dual Task Conditions.

Harada N, Okada S, Negoro S - Curr Gerontol Geriatr Res (2010)

An example of step response data. From top to bottom: Tap cue on back of heel; COPx = Mediolateral center of pressure; Fx =  Ground reaction force in lateral direction; Fy = Ground reaction force in anteroposterior direction; Fz = Vertical ground reaction force. The stepping task was divided into four phases: (1) the initiation phase (I) was calculated from the tap cue to the onset (OT); (2) the preparatory phase (P) was calculated from OT to foot-off for the right leg (rFO); (3) the swing phase (S) was calculated from rFO to foot-contact for the right leg (rFC); (4) the double-stance  stance phase (D) was calculated from rFC to foot-off for the left leg (lFO).
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2877204&req=5

fig1: An example of step response data. From top to bottom: Tap cue on back of heel; COPx = Mediolateral center of pressure; Fx = Ground reaction force in lateral direction; Fy = Ground reaction force in anteroposterior direction; Fz = Vertical ground reaction force. The stepping task was divided into four phases: (1) the initiation phase (I) was calculated from the tap cue to the onset (OT); (2) the preparatory phase (P) was calculated from OT to foot-off for the right leg (rFO); (3) the swing phase (S) was calculated from rFO to foot-contact for the right leg (rFC); (4) the double-stance stance phase (D) was calculated from rFC to foot-off for the left leg (lFO).
Mentions: The method for the data analysis of the present study was taken from Brauer et al. [14] and Melzer and Oddsson [15]. The COPx (Mediolateral center of pressure) and the ground reaction force data (Fx = ground reaction force in lateral direction; Fy = ground reaction force in anterior-posterior direction; Fz = vertical ground reaction force) have been described in terms of the length of events during the stepping task (Figure 1); onset time (OT) was determined as the first medio-lateral shift of the COPx (COPx excursion greater than 10 mm away from the baseline following the tap). Time of foot-off for the right limb (rFO) was determined from the trace of Fy, the first lowest peak value at approximately the same time as the trace of Fz and the first highest peak value following OT. The second peak value of the vertical force (Fz) was used to determine the time of foot-contact (rFC), and it was nearly equivalent to the second lowest peak value of Fy. The time of foot-off for left limb (lFO) was determined when the trace of COPx reached its final stable value.

Bottom Line: For the second experiment, they stepped on a soft surface placed in front of them while performing the above tasks.The main result was that %DIP (initiation phase as a percentage of the total stepping task time) was significantly higher for older than for young adults during the dual task on the soft surface.In conclusion, caution due to previous experience may increase attentional demand during dual tasks and lengthen the time required for central nervous processing in order to avoid losing postural stability in older adults, resulting in reductions in step velocity and step length compared to those in young adults.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Human Development and Environment, Kobe University, 3-11 Tsurukabuto, Nada-ku, Kobe 657-8501, Japan.

ABSTRACT
The purpose of this study was to investigate whether age-related differences in stepping response influence postural control when stepping onto a known soft surface under dual task conditions. Nine young and eleven older female adults participated. First, they stepped on a flat surface while grasping an empty cup (single task), and then they repeated the task while grasping a cup filled with water (dual task). For the second experiment, they stepped on a soft surface placed in front of them while performing the above tasks. The main result was that %DIP (initiation phase as a percentage of the total stepping task time) was significantly higher for older than for young adults during the dual task on the soft surface. In conclusion, caution due to previous experience may increase attentional demand during dual tasks and lengthen the time required for central nervous processing in order to avoid losing postural stability in older adults, resulting in reductions in step velocity and step length compared to those in young adults.

No MeSH data available.