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Table 2.

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

	Individuals
EMG variable	r	P	r	P	r	P
Stance femoral retractors	INDIVIDUAL 2
FTE REL ON	—0.669	<0.001^{^*}
FTE REL OFF	—0.768	<0.001^{^*}
FTE DUR	—0.661	<0.001^{^*}
FTE DUR STANCE	—0.193	0.306
FTE AREA	0.147	0.440
FTE AREA DUR	0.612	<0.001^{^*}
FTE AD STANCE	0.571	0.001^{^*}
Stance femoral adductors
ADDFEM		No significant correlations (Individuals 1, 4 and 5)
	INDIVIDUAL 1			INDIVIDUAL 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	—0.426	0.019	—0.514	<0.001^{^*}
PIFE3 DUR STANCE	—0.105	0.582	—0.130	0.494
PIFE3 AREA	0.575	0.001^{^*}	0.679	<0.001^{^*}
PIFE3 AREA DUR	0.768	<0.001^{^*}	0.751	<0.001^{^*}
PIFE3 AD STANCE	0.719	<0.001^{^*}	0.679	<0.001^{^*}
PIT (a) REL ON	0.018	0.924
PIT (a) REL OFF	0.023	0.906
PIT (a) DUR	0.143	0.451
PIT (a) DUR STANCE	0.310	0.096
PIT (a) AREA	0.334	0.071
PIT (a) AREA DUR	0.474	0.008
PIT (a) AD STANCE	0.528	0.003^{^*}
Stance knee extensors	INDIVIDUAL 1			INDIVIDUAL 2			INDIVIDUAL 4
FEMTIB REL ON	0.051	0.789	—0.089	0.639	0.053	0.779
FEMTIB REL OFF	—0.164	0.388	—0.222	0.239	0.208	0.271
FEMTIB DUR	—0.203	0.282	—0.146	0.440	0.211	0.263
FEMTIB DUR STANCE	0.294	0.115	0.336	0.070	0.291	0.119
FEMTIB AREA	0.370	0.044	0.694	<0.001^{^*}	0.802	<0.001^{^*}
FEMTIB AREA DUR	0.668	<0.001^{^*}	0.723	<0.001^{^*}	0.719	<0.001^{^*}
FEMTIB AD STANCE	0.669	<0.001^{^*}	0.653	<0.001^{^*}	0.590	0.001^{^*}
ILTIBI		No significant correlations (Individual 5)
	INDIVIDUAL 4			INDIVIDUAL 5
ILTIB2 REL ON	0.079	0.677	—0.287	0.123
ILTIB2 REL OFF	0.333	0.072	0.056	0.770
ILTIB2 DUR	0.128	0.500	0.197	0.296
ILTIB2 DUR STANCE	0.147	0.439	0.061	0.747
ILTIB2 AREA	0.863	<0.001^{^*}	0.840	<0.001^{^*}
ILTIB2 AREA DUR	0.774	<0.001^{^*}	0.774	<0.001^{^*}
ILTIB2 AD STANCE	0.622	<0.001^{^*}	0.651	<0.001^{^*}
Stance ankle extensors	INDIVIDUAL 3			INDIVIDUAL 4			INDIVIDUAL 5
GAST REL ON	0.169	0.363	0.116	0.540	—0.206	0.275
GAST REL OFF	0.118	0.529	—0.200	0.290	—0.041	0.828
GAST DUR	—0.077	0.681	—0.157	0.408	0.335	0.071
GAST DUR STANCE	—0.023	0.900	—0.086	0.652	0.178	0.347
GAST AREA	0.651	<0.001^{^*}	0.535	0.002^{^*}	0.760	<0.001^{^*}
GAST AREA DUR	0.702	<0.001^{^*}	0.643	<0.001^{^*}	0.790	<0.001^{^*}
GAST AD STANCE	0.640	<0.001^{^*}	0.602	<0.001^{^*}	0.518	0.003^{^*}
Swing femoral protractors	INDIVIDUAL 5
PIFI2 REL ON	0.289	0.122
PIFI2 REL OFF	0.421	0.021
PIFI2 DUR	0.296	0.112
PIFI2 DUR SWING	0.488	0.006^{^*}
PIFI2 AREA	0.412	0.024
PIFI2 AREA DUR	0.144	0.449
PIFI2 AD SWING	0.356	0.054
Swing femoral abductors	INDIVIDUAL 4
ILFEM REL ON	0.405	0.027
ILFEM REL OFF	—0.212	0.261
ILFEM DUR	—0.734	<0.001^{^*}
ILFEM DUR SWING	—0.656	<0.001^{^*}
ILFEM AREA	—0.586	0.001^{^*}
ILFEM AREA DUR	0.649	<0.001^{^*}
ILFEM AD SWING	0.540	0.002^{^*}
Swing knee extensors
AMB 1	No significant correlations (Individuals 3 and 5)
Swing knee flexors	INDIVIDUAL 1
PIT (b) REL ON	—0.288	0.122
PIT (b) REL OFF	—0.494	0.005^{^*}
PIT (b) DUR	—0.479	0.007^{^*}
PIT (b) DUR SWING	—0.351	0.057
PIT (b) AREA	—0.400	0.029
PIT (b) AREA DUR	0.382	0.037
PIT (b) AD SWING	0.335	0.070
Swing ankle flexors	INDIVIDUAL 3			INDIVIDUAL 4
TA REL ON	0.023	0.902	0.214	0.257
TA REL OFF	0.038	0.839	—0.046	0.808
TA DUR	0.137	0.462	—0.151	0.426
TA DUR SWING	0.062	0.742	0.048	0.800
TA AREA	0.634	<0.001^{^*}	0.875	<0.001^{^*}
TA AREA DUR	0.804	<0.001^{^*}	0.862	<0.001^{^*}
TA AD SWING	0.590	<0.001^{^*}	0.804	<0.001^{^*}

	Individuals
EMG variable	r	P	r	P	r	P
Stance femoral retractors	INDIVIDUAL 2
FTE REL ON	—0.669	<0.001^{^*}
FTE REL OFF	—0.768	<0.001^{^*}
FTE DUR	—0.661	<0.001^{^*}
FTE DUR STANCE	—0.193	0.306
FTE AREA	0.147	0.440
FTE AREA DUR	0.612	<0.001^{^*}
FTE AD STANCE	0.571	0.001^{^*}
Stance femoral adductors
ADDFEM		No significant correlations (Individuals 1, 4 and 5)
	INDIVIDUAL 1			INDIVIDUAL 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	—0.426	0.019	—0.514	<0.001^{^*}
PIFE3 DUR STANCE	—0.105	0.582	—0.130	0.494
PIFE3 AREA	0.575	0.001^{^*}	0.679	<0.001^{^*}
PIFE3 AREA DUR	0.768	<0.001^{^*}	0.751	<0.001^{^*}
PIFE3 AD STANCE	0.719	<0.001^{^*}	0.679	<0.001^{^*}
PIT (a) REL ON	0.018	0.924
PIT (a) REL OFF	0.023	0.906
PIT (a) DUR	0.143	0.451
PIT (a) DUR STANCE	0.310	0.096
PIT (a) AREA	0.334	0.071
PIT (a) AREA DUR	0.474	0.008
PIT (a) AD STANCE	0.528	0.003^{^*}
Stance knee extensors	INDIVIDUAL 1			INDIVIDUAL 2			INDIVIDUAL 4
FEMTIB REL ON	0.051	0.789	—0.089	0.639	0.053	0.779
FEMTIB REL OFF	—0.164	0.388	—0.222	0.239	0.208	0.271
FEMTIB DUR	—0.203	0.282	—0.146	0.440	0.211	0.263
FEMTIB DUR STANCE	0.294	0.115	0.336	0.070	0.291	0.119
FEMTIB AREA	0.370	0.044	0.694	<0.001^{^*}	0.802	<0.001^{^*}
FEMTIB AREA DUR	0.668	<0.001^{^*}	0.723	<0.001^{^*}	0.719	<0.001^{^*}
FEMTIB AD STANCE	0.669	<0.001^{^*}	0.653	<0.001^{^*}	0.590	0.001^{^*}
ILTIBI		No significant correlations (Individual 5)
	INDIVIDUAL 4			INDIVIDUAL 5
ILTIB2 REL ON	0.079	0.677	—0.287	0.123
ILTIB2 REL OFF	0.333	0.072	0.056	0.770
ILTIB2 DUR	0.128	0.500	0.197	0.296
ILTIB2 DUR STANCE	0.147	0.439	0.061	0.747
ILTIB2 AREA	0.863	<0.001^{^*}	0.840	<0.001^{^*}
ILTIB2 AREA DUR	0.774	<0.001^{^*}	0.774	<0.001^{^*}
ILTIB2 AD STANCE	0.622	<0.001^{^*}	0.651	<0.001^{^*}
Stance ankle extensors	INDIVIDUAL 3			INDIVIDUAL 4			INDIVIDUAL 5
GAST REL ON	0.169	0.363	0.116	0.540	—0.206	0.275
GAST REL OFF	0.118	0.529	—0.200	0.290	—0.041	0.828
GAST DUR	—0.077	0.681	—0.157	0.408	0.335	0.071
GAST DUR STANCE	—0.023	0.900	—0.086	0.652	0.178	0.347
GAST AREA	0.651	<0.001^{^*}	0.535	0.002^{^*}	0.760	<0.001^{^*}
GAST AREA DUR	0.702	<0.001^{^*}	0.643	<0.001^{^*}	0.790	<0.001^{^*}
GAST AD STANCE	0.640	<0.001^{^*}	0.602	<0.001^{^*}	0.518	0.003^{^*}
Swing femoral protractors	INDIVIDUAL 5
PIFI2 REL ON	0.289	0.122
PIFI2 REL OFF	0.421	0.021
PIFI2 DUR	0.296	0.112
PIFI2 DUR SWING	0.488	0.006^{^*}
PIFI2 AREA	0.412	0.024
PIFI2 AREA DUR	0.144	0.449
PIFI2 AD SWING	0.356	0.054
Swing femoral abductors	INDIVIDUAL 4
ILFEM REL ON	0.405	0.027
ILFEM REL OFF	—0.212	0.261
ILFEM DUR	—0.734	<0.001^{^*}
ILFEM DUR SWING	—0.656	<0.001^{^*}
ILFEM AREA	—0.586	0.001^{^*}
ILFEM AREA DUR	0.649	<0.001^{^*}
ILFEM AD SWING	0.540	0.002^{^*}
Swing knee extensors
AMB 1	No significant correlations (Individuals 3 and 5)
Swing knee flexors	INDIVIDUAL 1
PIT (b) REL ON	—0.288	0.122
PIT (b) REL OFF	—0.494	0.005^{^*}
PIT (b) DUR	—0.479	0.007^{^*}
PIT (b) DUR SWING	—0.351	0.057
PIT (b) AREA	—0.400	0.029
PIT (b) AREA DUR	0.382	0.037
PIT (b) AD SWING	0.335	0.070
Swing ankle flexors	INDIVIDUAL 3			INDIVIDUAL 4
TA REL ON	0.023	0.902	0.214	0.257
TA REL OFF	0.038	0.839	—0.046	0.808
TA DUR	0.137	0.462	—0.151	0.426
TA DUR SWING	0.062	0.742	0.048	0.800
TA AREA	0.634	<0.001^{^*}	0.875	<0.001^{^*}
TA AREA DUR	0.804	<0.001^{^*}	0.862	<0.001^{^*}
TA AD SWING	0.590	<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

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