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Table 1 Center-of-Pressure Calculations.

From: Enhanced balance associated with coordination training with stochastic resonance stimulation in subjects with functional ankle instability: an experimental trial

COPvel: The mean value of the instantaneous velocity of the COP in a given direction during a given time period A/P COPvel = t = 1 T | x cop,t x cop,t 1 Δ t | T 1 M/L COPvel = t = 1 T | y cop,t y cop,t 1 Δ t | T 1 MathType@MTEF@5@5@+=feaagaart1ev2aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacPC6xNi=xI8qiVKYPFjYdHaVhbbf9v8qqaqFr0xc9vqFj0dXdbba91qpepeI8k8fiI+fsY=rqGqVepae9pg0db9vqaiVgFr0xfr=xfr=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@8B75@
M/L COPsd: Overall standard deviation of sway in the M/L direction in a given time period for a given number of trials M/L COPsd = n = 1 N t = 0 T Sway M / L,t,n 2 ( n = 1 N t = 0 T Sway M/L,t,n ) 2 N ( T 1 ) NT 1 Sway M/L = t = 0 T | COP M/L,t COP M/L,mean | T MathType@MTEF@5@5@+=feaagaart1ev2aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacPC6xNi=xI8qiVKYPFjYdHaVhbbf9v8qqaqFr0xc9vqFj0dXdbba91qpepeI8k8fiI+fsY=rqGqVepae9pg0db9vqaiVgFr0xfr=xfr=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@A8E3@
COParea: An area defined by the maximum (max) anterior (ant), posterior (post), medial (med), and lateral (lat) sways during a given time period. COParea = ( Sway max,ant + Sway max,post ) × ( Sway max,med + Sway max,lat ) T Sway max,direction = t = 0 T | COP direction,t COP direction,mean | T MathType@MTEF@5@5@+=feaagaart1ev2aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacPC6xNi=xI8qiVKYPFjYdHaVhbbf9v8qqaqFr0xc9vqFj0dXdbba91qpepeI8k8fiI+fsY=rqGqVepae9pg0db9vqaiVgFr0xfr=xfr=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@C849@
M/L COPmax: Maximum distance between the instantaneous COP position and the average COP position during a given time period. M/L COPmax = t = 0 T | COP max,M/L COP M/L,mean | T MathType@MTEF@5@5@+=feaagaart1ev2aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacPC6xNi=xI8qiVKYPFjYdHaVhbbf9v8qqaqFr0xc9vqFj0dXdbba91qpepeI8k8fiI+fsY=rqGqVepae9pg0db9vqaiVgFr0xfr=xfr=xc9adbaqaaeGacaGaaiaabeqaaeqabiWaaaGcbaGaeeyta0Kaee4la8IaeeitaWKaeeiiaaIaee4qamKaee4ta8KaeeiuaaLaeeyBa0MaeeyyaeMaeeiEaGNaeyypa0tcfa4aaSaaaeaadaaeWbqaamaaemaabaGaee4qamKaee4ta8Kaeeiuaa1aaSbaaeaacqqGTbqBcqqGHbqycqqG4baEcqqGSaalcqqGnbqtcqqGVaWlcqqGmbataeqaaiabgkHiTiabboeadjabb+eapjabbcfaqnaaBaaabaGaeeyta0Kaee4la8IaeeitaWKaeeilaWIaeeyBa0MaeeyzauMaeeyyaeMaeeOBa4gabeaaaiaawEa7caGLiWoaaeaacqqG0baDcqGH9aqpcqaIWaamaeaacqqGubavaiabggHiLdaabaGaeeivaqfaaaaa@5DA0@
  1. Calculations for the following postural stability measures are presented in Table 1: Anterior/Posterior Center-of-Pressure Velocity (A/P COPvel); Medial/Lateral Center-of-Pressure Velocity (M/L COPvel); Medial/Lateral Center-of-Pressure Standard Deviation (M/L COPsd); Center-of-Pressure Area (COParea); and Medial/Lateral Center-of-Pressure Maximum Excursion (M/L COPmax). t = A given time point; T = Number of data points per trial; N = Number of trials