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AGEING AND PRIORITIZATION OF DYNAMIC STABILITY CONTROL FOLLOWING GAIT PERTURBATIONS
S224
Presentation 1111 − Topic 20. Gait and posture
AGEING AND PRIORITIZATION OF DYNAMIC STABILITY CONTROL FOLLOWING GAIT PERTURBATIONS Falk Mersmann (1), Sebastian Bohm (1), Stefanie Bierbaum (1), Ralf Dietrich (1), Adamantios Arampatzis (1,2)
1. Humboldt-Universität zu Berlin, Germany; 2. Center for Sports Science and Sports Medicine Berlin, Germany
Introduction A growing body of evidence suggests the involvement of high-level processing in the modulation of reactive balance adjustments [Maki, 2007]. When two tasks compete for finite cognitive resources, prioritization affects the impairment of one or both tasks [Siu, 2009]. The purpose of the present study was to investigate the interference between cognitive performance and dynamic stability control during unexpected gait perturbations in young and old adults.
As a response to the postural threat, all groups (yet more markedly the young groups) significantly increased the base of support with the subsequent step (Base: 110.75±1.68 cm; P: 119.02±2.35 cm; p < 0.05). The unexpected perturbation induced a deterioration of cognitive task performance in the dual task groups. The number of faults increased significantly in both groups (Base: 0.13±0.2; P: 0.48±0.4; p < 0.05), the response times only in the young group (Base: 1.36±0.2 s; P: 1.91±0.6 s; p < 0.05).
Method Thirty-two young (mean age 27.1 years) and 30 elderly (mean age 69.0 years) physically active male subjects participated in the present study and were randomly assigned to either control or dual task group. Beneath a covered exchangeable element, positioned halfway along a gangway, a foam block provided the compliant surface for the unexpected perturbation trials. The groups performed three baseline (Base) and one unexpected perturbation trial (P), walking with selfselected gait velocity. The dual task groups performed a concurrent cognitive task, adjusted in the level of difficulty. The subjects executed respective mathematical operations according to the type of auditory cue and verbalized the result. Whole body kinematic data was recorded to quantify dynamic stability based on the ‘extrapolated center of mass’ concept proposed by Hof et al. [2005]. Gait velocity and body height were used as covariates in an ANOVA with the fixed factors age (young, old), condition (control, dual task) and trial (baseline, perturbation).
Results There were no condition effects or interactions on the margin of stability (MoS) at touchdown of the recovery leg (Figure 1). Therefore, the concurrent cognitive task did not affect stability performance. The significantly greater (p < 0.05) MoS values of the elderly, also valid in the baseline trials, were due to the lower gait velocity. Following the perturbation the MoS decreased significantly in both age groups (p <0 .05). This decrease indicates a less stable body position at touchdown of the recovery leg and was, especially in relation to baseline values, more prominent in the old groups (Average decrease: Young: -8.2 cm; Old: -9.1 cm). Journal of Biomechanics 45(S1)
Figure 1: Mean values and standard error of mean of the margin of stability at touchdown of the recovery leg of young control (YC, n = 15), young dual task (YDT, n = 17), old control (OC, n = 16) and old dual task group (ODT, n = 14) under baseline (Base) and perturbed gait condition (Soft). * significant trial effect, + significant age effect
Discussion Our results suggest (a) that the modulation of balance recovery following gait perturbations relies on high-level processing and (b) that healthy old as well as young adults prioritize dynamic stability control over a cognitive task facing a severe threat to save locomotion. It is assumed that, in line with the “posture first” strategy, processing resources were reallocated to preserve balance recovery performance.
References Hof et al, J Biomech, 38: 1-8, 2005. Maki et al, J Neural Transm, 114: 1279-96, 2007. Siu et al, Brain Res, 1248: 59–67, 2009.
ESB2012: 18th Congress of the European Society of Biomechanics
Presentation 1111 − Topic 20. Gait and posture
AGEING AND PRIORITIZATION OF DYNAMIC STABILITY CONTROL FOLLOWING GAIT PERTURBATIONS Falk Mersmann (1), Sebastian Bohm (1), Stefanie Bierbaum (1), Ralf Dietrich (1), Adamantios Arampatzis (1,2)
1. Humboldt-Universität zu Berlin, Germany; 2. Center for Sports Science and Sports Medicine Berlin, Germany
Introduction A growing body of evidence suggests the involvement of high-level processing in the modulation of reactive balance adjustments [Maki, 2007]. When two tasks compete for finite cognitive resources, prioritization affects the impairment of one or both tasks [Siu, 2009]. The purpose of the present study was to investigate the interference between cognitive performance and dynamic stability control during unexpected gait perturbations in young and old adults.
As a response to the postural threat, all groups (yet more markedly the young groups) significantly increased the base of support with the subsequent step (Base: 110.75±1.68 cm; P: 119.02±2.35 cm; p < 0.05). The unexpected perturbation induced a deterioration of cognitive task performance in the dual task groups. The number of faults increased significantly in both groups (Base: 0.13±0.2; P: 0.48±0.4; p < 0.05), the response times only in the young group (Base: 1.36±0.2 s; P: 1.91±0.6 s; p < 0.05).
Method Thirty-two young (mean age 27.1 years) and 30 elderly (mean age 69.0 years) physically active male subjects participated in the present study and were randomly assigned to either control or dual task group. Beneath a covered exchangeable element, positioned halfway along a gangway, a foam block provided the compliant surface for the unexpected perturbation trials. The groups performed three baseline (Base) and one unexpected perturbation trial (P), walking with selfselected gait velocity. The dual task groups performed a concurrent cognitive task, adjusted in the level of difficulty. The subjects executed respective mathematical operations according to the type of auditory cue and verbalized the result. Whole body kinematic data was recorded to quantify dynamic stability based on the ‘extrapolated center of mass’ concept proposed by Hof et al. [2005]. Gait velocity and body height were used as covariates in an ANOVA with the fixed factors age (young, old), condition (control, dual task) and trial (baseline, perturbation).
Results There were no condition effects or interactions on the margin of stability (MoS) at touchdown of the recovery leg (Figure 1). Therefore, the concurrent cognitive task did not affect stability performance. The significantly greater (p < 0.05) MoS values of the elderly, also valid in the baseline trials, were due to the lower gait velocity. Following the perturbation the MoS decreased significantly in both age groups (p <0 .05). This decrease indicates a less stable body position at touchdown of the recovery leg and was, especially in relation to baseline values, more prominent in the old groups (Average decrease: Young: -8.2 cm; Old: -9.1 cm). Journal of Biomechanics 45(S1)
Figure 1: Mean values and standard error of mean of the margin of stability at touchdown of the recovery leg of young control (YC, n = 15), young dual task (YDT, n = 17), old control (OC, n = 16) and old dual task group (ODT, n = 14) under baseline (Base) and perturbed gait condition (Soft). * significant trial effect, + significant age effect
Discussion Our results suggest (a) that the modulation of balance recovery following gait perturbations relies on high-level processing and (b) that healthy old as well as young adults prioritize dynamic stability control over a cognitive task facing a severe threat to save locomotion. It is assumed that, in line with the “posture first” strategy, processing resources were reallocated to preserve balance recovery performance.
References Hof et al, J Biomech, 38: 1-8, 2005. Maki et al, J Neural Transm, 114: 1279-96, 2007. Siu et al, Brain Res, 1248: 59–67, 2009.
ESB2012: 18th Congress of the European Society of Biomechanics