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=xc9adbaqaaeGacaGaaiaabeqaaeqabiWaaaGcbaqbaeaabiqaaaqaaiabbgeabjabb+caViabbcfaqjabbccaGiabboeadjabb+eapjabbcfaqjabbAha2jabbwgaLjabbYgaSjabg2da9KqbaoaalaaabaWaaabCaeaadaabdaqaamaalaaabaGaeeiEaG3aaSbaaeaacqqGJbWycqqGVbWBcqqGWbaCcqqGSaalcqqG0baDaeqaaiabgkHiTiabbIha4naaBaaabaGaee4yamMaee4Ba8MaeeiCaaNaeeilaWIaeeiDaqNaeyOeI0IaeGymaedabeaaaeaacqqHuoarcqqG0baDaaaacaGLhWUaayjcSdaabaGaeeiDaqNaeyypa0JaeGymaedabaGaeeivaqfacqGHris5aaqaaiabbsfaujabgkHiTiabigdaXaaaaOqaaiabb2eanjabb+caViabbYeamjabbccaGiabboeadjabb+eapjabbcfaqjabbAha2jabbwgaLjabbYgaSjabg2da9KqbaoaalaaabaWaaabCaeaadaabdaqaamaalaaabaGaeeyEaK3aaSbaaeaacqqGJbWycqqGVbWBcqqGWbaCcqqGSaalcqqG0baDaeqaaiabgkHiTiabbMha5naaBaaabaGaee4yamMaee4Ba8MaeeiCaaNaeeilaWIaeeiDaqNaeyOeI0IaeGymaedabeaaaeaacqqHuoarcqqG0baDaaaacaGLhWUaayjcSdaabaGaeeiDaqNaeyypa0JaeGymaedabaGaeeivaqfacqGHris5aaqaaiabbsfaujabgkHiTiabigdaXaaaaaaaaa@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@