Introduction: Ageing is associated with a decline in balance and an increased risk of falling, mainly during transitory locomotor tasks such as gait initiation and termination [1]. One of the main factors underpinning the balance impairment in older individuals is a decrease in head stability, which is partly due to an increased variability of trunk motion, as previously shown during gait initiation [2]. However, it is unclear whether an altered recruitment of the upper body muscles could also contribute to the increased variability of the upper body motion while terminating gait. Therefore, the purpose of this study was to evaluate activity patterns of the trunk muscles as well as movement variability of the upper body segments during gait termination in young and older women. Methods: Ten young (age: 23.1 ± 1.1) and 10 older women (age: 73.8 ± 2.4) performed three trials of gait termination at their self-selected fast speed. A stereophotogrammetric system (VICON, UK) was used to assess angular displacement of head, trunk and pelvis along the sagittal and frontal planes through the Plug-in Gait model. Movement variability was determined by calculating the average standard deviation (AvgSD) of angular displacement of head, trunk and pelvis [2]. An electromyography device (BTS, Italia) was used to record activity of the left erector spinae muscle at T9 (EST) and at L3 level (ESL). Principal component (PC) analysis was used to evaluate the most common patterns of muscle activation within the two groups [3]. Results: AvgSD of the trunk angular displacement along the sagittal plane was higher in older than young women (1.77° ± 0.98° and 1.02° ± 0.29°, respectively; p < 0.05). Older women displayed higher AvgSD of head angular displacement along the frontal plane compared to young women (2.48° ± 0.81° and 1.61° ± 0.37°, respectively; p < 0.05). PC analysis of the EST muscle waveforms showed that the first four PCs explained 64% and 61% of the total variance in older and young women, respectively. On the other hand, the PC analysis of the ESL waveforms highlighted that four PCs explained 65% of total variance in the older women, while three PCs explained 70% of total variance in young women (Fig. 1). Moreover, visual inspection of the first PC highlighted a delayed activation of the ESL during the braking phase in older women compared to young women. Discussion: The increase in movement of the trunk and head along the sagittal and frontal planes, respectively, in older women is in line with previous reports on gait initiation [2]. At neuromuscular level, the higher number of PCs found in older women compared to young women indicated an age-related increase in the variability of muscle activation patterns of the lower trunk during gait termination. The results of the present study, therefore, suggested that an increase in neuromuscular variability of the lower trunk is a major factor underpinning the loss of stability in the upper body during such transitory locomotor task in older women.
Mechanisms of trunk stabilization during gait termination in young and older women: A neuromechanical analysis
L. Rum
;
2017-01-01
Abstract
Introduction: Ageing is associated with a decline in balance and an increased risk of falling, mainly during transitory locomotor tasks such as gait initiation and termination [1]. One of the main factors underpinning the balance impairment in older individuals is a decrease in head stability, which is partly due to an increased variability of trunk motion, as previously shown during gait initiation [2]. However, it is unclear whether an altered recruitment of the upper body muscles could also contribute to the increased variability of the upper body motion while terminating gait. Therefore, the purpose of this study was to evaluate activity patterns of the trunk muscles as well as movement variability of the upper body segments during gait termination in young and older women. Methods: Ten young (age: 23.1 ± 1.1) and 10 older women (age: 73.8 ± 2.4) performed three trials of gait termination at their self-selected fast speed. A stereophotogrammetric system (VICON, UK) was used to assess angular displacement of head, trunk and pelvis along the sagittal and frontal planes through the Plug-in Gait model. Movement variability was determined by calculating the average standard deviation (AvgSD) of angular displacement of head, trunk and pelvis [2]. An electromyography device (BTS, Italia) was used to record activity of the left erector spinae muscle at T9 (EST) and at L3 level (ESL). Principal component (PC) analysis was used to evaluate the most common patterns of muscle activation within the two groups [3]. Results: AvgSD of the trunk angular displacement along the sagittal plane was higher in older than young women (1.77° ± 0.98° and 1.02° ± 0.29°, respectively; p < 0.05). Older women displayed higher AvgSD of head angular displacement along the frontal plane compared to young women (2.48° ± 0.81° and 1.61° ± 0.37°, respectively; p < 0.05). PC analysis of the EST muscle waveforms showed that the first four PCs explained 64% and 61% of the total variance in older and young women, respectively. On the other hand, the PC analysis of the ESL waveforms highlighted that four PCs explained 65% of total variance in the older women, while three PCs explained 70% of total variance in young women (Fig. 1). Moreover, visual inspection of the first PC highlighted a delayed activation of the ESL during the braking phase in older women compared to young women. Discussion: The increase in movement of the trunk and head along the sagittal and frontal planes, respectively, in older women is in line with previous reports on gait initiation [2]. At neuromuscular level, the higher number of PCs found in older women compared to young women indicated an age-related increase in the variability of muscle activation patterns of the lower trunk during gait termination. The results of the present study, therefore, suggested that an increase in neuromuscular variability of the lower trunk is a major factor underpinning the loss of stability in the upper body during such transitory locomotor task in older women.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
