Table 2.

Correlations between hindlimb motor patterns and the use of more upright limb postures in Alligator

Individuals
EMG variablerPrPrP
Stance femoral retractorsINDIVIDUAL 2
   FTE REL ON—0.669<0.001*
   FTE REL OFF—0.768<0.001*
   FTE DUR—0.661<0.001*
   FTE DUR STANCE—0.1930.306
   FTE AREA0.1470.440
   FTE AREA DUR0.612<0.001*
   FTE AD STANCE0.5710.001*
Stance femoral adductors
   ADDFEMNo significant correlations (Individuals 1, 4 and 5)
INDIVIDUAL 1INDIVIDUAL 2
   PIFE3 REL ON—0.609<0.001*—0.673<0.001*
   PIFE3 REL OFF—0.667<0.001*—0.675<0.001*
   PIFE3 DUR—0.4260.019—0.514<0.001*
   PIFE3 DUR STANCE—0.1050.582—0.1300.494
   PIFE3 AREA0.5750.001*0.679<0.001*
   PIFE3 AREA DUR0.768<0.001*0.751<0.001*
   PIFE3 AD STANCE0.719<0.001*0.679<0.001*
   PIT (a) REL ON0.0180.924
   PIT (a) REL OFF0.0230.906
   PIT (a) DUR0.1430.451
   PIT (a) DUR STANCE0.3100.096
   PIT (a) AREA0.3340.071
   PIT (a) AREA DUR0.4740.008
   PIT (a) AD STANCE0.5280.003*
Stance knee extensorsINDIVIDUAL 1INDIVIDUAL 2INDIVIDUAL 4
   FEMTIB REL ON0.0510.789—0.0890.6390.0530.779
   FEMTIB REL OFF—0.1640.388—0.2220.2390.2080.271
   FEMTIB DUR—0.2030.282—0.1460.4400.2110.263
   FEMTIB DUR STANCE0.2940.1150.3360.0700.2910.119
   FEMTIB AREA0.3700.0440.694<0.001*0.802<0.001*
   FEMTIB AREA DUR0.668<0.001*0.723<0.001*0.719<0.001*
   FEMTIB AD STANCE0.669<0.001*0.653<0.001*0.5900.001*
   ILTIBINo significant correlations (Individual 5)
INDIVIDUAL 4INDIVIDUAL 5
   ILTIB2 REL ON0.0790.677—0.2870.123
   ILTIB2 REL OFF0.3330.0720.0560.770
   ILTIB2 DUR0.1280.5000.1970.296
   ILTIB2 DUR STANCE0.1470.4390.0610.747
   ILTIB2 AREA0.863<0.001*0.840<0.001*
   ILTIB2 AREA DUR0.774<0.001*0.774<0.001*
   ILTIB2 AD STANCE0.622<0.001*0.651<0.001*
Stance ankle extensorsINDIVIDUAL 3INDIVIDUAL 4INDIVIDUAL 5
   GAST REL ON0.1690.3630.1160.540—0.2060.275
   GAST REL OFF0.1180.529—0.2000.290—0.0410.828
   GAST DUR—0.0770.681—0.1570.4080.3350.071
   GAST DUR STANCE—0.0230.900—0.0860.6520.1780.347
   GAST AREA0.651<0.001*0.5350.002*0.760<0.001*
   GAST AREA DUR0.702<0.001*0.643<0.001*0.790<0.001*
   GAST AD STANCE0.640<0.001*0.602<0.001*0.5180.003*
Swing femoral protractorsINDIVIDUAL 5
   PIFI2 REL ON0.2890.122
   PIFI2 REL OFF0.4210.021
   PIFI2 DUR0.2960.112
   PIFI2 DUR SWING0.4880.006*
   PIFI2 AREA0.4120.024
   PIFI2 AREA DUR0.1440.449
   PIFI2 AD SWING0.3560.054
Swing femoral abductorsINDIVIDUAL 4
   ILFEM REL ON0.4050.027
   ILFEM REL OFF—0.2120.261
   ILFEM DUR—0.734<0.001*
   ILFEM DUR SWING—0.656<0.001*
   ILFEM AREA—0.5860.001*
   ILFEM AREA DUR0.649<0.001*
   ILFEM AD SWING0.5400.002*
Swing knee extensors
   AMB 1No significant correlations (Individuals 3 and 5)
Swing knee flexorsINDIVIDUAL 1
   PIT (b) REL ON—0.2880.122
   PIT (b) REL OFF—0.4940.005*
   PIT (b) DUR—0.4790.007*
   PIT (b) DUR SWING—0.3510.057
   PIT (b) AREA—0.4000.029
   PIT (b) AREA DUR0.3820.037
   PIT (b) AD SWING0.3350.070
Swing ankle flexorsINDIVIDUAL 3INDIVIDUAL 4
   TA REL ON0.0230.9020.2140.257
   TA REL OFF0.0380.839—0.0460.808
   TA DUR0.1370.462—0.1510.426
   TA DUR SWING0.0620.7420.0480.800
   TA AREA0.634<0.001*0.875<0.001*
   TA AREA DUR0.804<0.001*0.862<0.001*
   TA AD SWING0.590<0.001*0.804<0.001*
  • Correlation coefficients (r) and significance levels (P) for regressions of electromyographic variables on femoral posture, based on N=30 strides per individual spanning the femoral posture ranges given in Table 1 (positive correlations indicate increases in the variable with more upright posture).

    The prefix of each variable name is the abbreviation for the muscle (see Myology), and the suffix describes the EMG variable: REL ON, burst onset relative to foot-down; REL OFF, burst offset relative to foot-down; DUR, burst duration; DUR STANCE, burst duration normalized by stance duration; DUR SWING, burst duration normalized by swing duration; AREA, rectified burst area; AREA DUR, rectified area normalized by burst duration (i.e. mean burst amplitude); AD STANCE, mean burst amplitude normalized by stance duration; AD SWING, mean burst amplitude normalized by swing duration. For PIT, letters denote the stance (a) and swing (b) phase activity bursts for this muscle.

  • * Significant (P<0.05) with sequential Bonferroni correction, N=7 variables per muscle