Correlations between force plate measures for assessment of balance.
ABSTRACT To compare different force plate measures for assessment of postural stability during normal standing. Five types of measures were analysed: (1) The standard deviation of the horizontal ground reaction force, (2) the standard deviation of the centre of pressure, (3) the mean velocity of the centre of pressure, (4) movement strategy measures, and (5) the standard deviation of the vertical ground reaction force.
Force plate measures such as types 1-3 are frequently used, but they seem to have limited usefulness for assessment of balance on an individual level. Hence, there is a need to investigate alternative force plate measures (such as types 4 and 5).
Force plate measures for 20 stroke patients were (a) compared to each other, and (b) compared to a clinical balance test, called Berg's balance test.
There was generally a significant correlation (P<0.01) between measures of types 1-3. The movement strategy measures were not significantly correlated to any of the other measures. The vertical force measure was only significantly correlated to the antero-posterior mean velocity of the centre of pressure. There was a significant correlation between (a) Berg's balance test and the vertical force measure (r(s)=-0.76), and (b) the static part of Berg's balance test and the antero-posterior mean velocity of the centre of pressure (r(s)=-0.6).
Measures of type 1, 2, 4 and 5 seem to quantify different aspects of human standing. The results also indicate that Berg's balance test and the vertical force measure quantify a similar aspect of the postural stability.
The results from this study may facilitate the understanding and interpretation of force plate measures.
Article: Assessment of the centre of pressure pattern and moments about S2 in scoliotic subjects during normal walking.[show abstract] [hide abstract]
ABSTRACT: Research employing gait measurements indicate asymmetries in ground reaction forces and suggest relationships between these asymmetries, neurological dysfunction and spinal deformity. Although, studies have documented the use of centre of pressure (CoP) and net joint moments in gait assessment and have assessed centre of mass (CoM)-CoP distance relationships in clinical conditions, there is a paucity of information relating to the moments about CoM. It is commonly considered that CoM is situated around S2 vertebra in normal upright posture and hence this study uses S2 vertebral prominence as reference point relative to CoM. To assess and establish asymmetry in the CoP pattern and moments about S2 vertebral prominence during level walking and its relationship to spinal deformity in adolescents with scoliosis. Nine Adolescent Idiopathic Scoliosis subjects (8 females and 1 male with varying curve magnitudes and laterality) scheduled for surgery within 2-3 days after data collection, took part in this study. Kinetic and Kinematic Gait assessment was performed with an aim to estimate the CoP displacement and the moments generated by the ground reaction force about the S2 vertebral prominence during left and right stance during normal walking. The study employed a strain gauge force platform to estimate the medio-lateral and anterior-posterior displacement of COP and a six camera motion analysis system to track the reflective markers to assess the kinematics. The data were recorded simultaneously. Results indicate wide variations in the medio lateral direction CoP, which could be related to the laterality of both the main and compensation curves. This variation is not evident in the anterior-posterior direction. Similar results were recorded for moments about S2 vertebral prominence. Subjects with higher left compensation curve had greater displacement to the left. Although further longitudinal studies are needed, results indicate that the variables identified in this study are applicable to initial screening and surgical evaluation of scoliosis.Scoliosis 02/2008; 3:10. · 1.31 Impact Factor
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ABSTRACT: This pilot study aimed to assess the differences in center of pressure trajectory in neuropathic patients with steppage gait. Steppage gait has previously been evaluated by several biomechanical methods, but plantar pressure distribution has been much less studied. The purpose of this study was to analyze the changes in center of pressure trajectory using a force plate. The steppage gait group was selected from the patients using drop foot brace (25 male) and the control group was selected from Isfahan university students (20 male). They walked at self- selected speed at a mean of ten trials (+2) to collect the center of pressure using a force plate. Center of pressure patterns were categorized into four patterns based on the center of pressure displacement magnitude (spatial features) through time (temporal features) when the longitudinal axis of the insole was plotted as the Y- axis and the transverse axis of the insole as X- axis during stance phase. The horizontal angle measured from center of pressure linear regression was positive in the control group (4.6 ± 2.4) (p < 0.005), but negative in the patient group (- 2.3 ± 1.6) (p < 0.005). The finding of this research measured center of pressure trajectory in steppage gait over time, which is useful for designing better shoe sole and also orthopaedic device and better understanding of stability in patients with drop foot.Journal of research in medical sciences 01/2010; 15(1):33-40. · 0.46 Impact Factor
Article: A body sensor network with electromyogram and inertial sensors: multimodal interpretation of muscular activities.[show abstract] [hide abstract]
ABSTRACT: The evaluation of the postural control system (PCS) has applications in rehabilitation, sports medicine, gait analysis, fall detection, and diagnosis of many diseases associated with a reduction in balance ability. Standing involves significant muscle use to maintain balance, making standing balance a good indicator of the health of the PCS. Inertial sensor systems have been used to quantify standing balance by assessing displacement of the center of mass, resulting in several standardized measures. Electromyogram (EMG) sensors directly measure the muscle control signals. Despite strong evidence of the potential of muscle activity for balance evaluation, less study has been done on extracting unique features from EMG data that express balance abnormalities. In this paper, we present machine learning and statistical techniques to extract parameters from EMG sensors placed on the tibialis anterior and gastrocnemius muscles, which show a strong correlation to the standard parameters extracted from accelerometer data. This novel interpretation of the neuromuscular system provides a unique method of assessing human balance based on EMG signals. In order to verify the effectiveness of the introduced features in measuring postural sway, we conduct several classification tests that operate on the EMG features and predict significance of different balance measures.IEEE transactions on information technology in biomedicine: a publication of the IEEE Engineering in Medicine and Biology Society 11/2009; 14(2):198-206. · 1.69 Impact Factor