Table 4. Comparison of muscle fiber characteristics between porcine skeletal muscles within the same parallel structural subtype

Traits	Muscle fiber type	Fan-shaped		Fusiform						Strap
Traits	Muscle fiber type	GR	(PE)	PM	ST	SM	VT	(PE)	p-value	IF	RA	(PE)	p-value
Cross-sectional area (μm²)	I	4,095.2	(285.4)	4,049.5^a	3,551.3^ab	2,756.6^bc	1,994.5^c	(239.9)	^***	4,403.5	3,802.6	(309.0)
	IIA	3,936.8	(224.3)	3,833.5^a	3,096.0^ab	1,817.3^b	1,576.8^b	(291.9)	^***	3,981.1^a	2,837.5^b	(419.8)	^*
	IIAX	4,462.2	(236.7)	3,398.9	nd	1,857.1	1,795.2	(304.6)		nd	3,311.6	(317.4)
	IIX	4,042.9	(285.4)	3,885.9^a	3,258.9^ab	2,268.4^b	2,835.2^ab	(233.2)	^**	4,042.3	3,761.0	(502.1)
	IIXB	2,967.6	(295.7)	4,578.1^a	3,245.7^ab	2,764.8^b	2,750.4^b	(289.6)	^*	4,283.7^a	3,104.0^b	(416.2)	^*
	IIB	3,897.4	(233.2)	4,170.9^a	2,736.1^b	3,166.6^ab	2,747.3^b	(233.4)		nd	2,932.3	(313.6)
	Mean	3,825.6	(247.7)	4,112.5^a	3,184.8^b	2,465.1^bc	2,328.2^c	(235.8)	^***	4,151.6^a	3,381.1^b	(312.0)	^*
Relative fiber area (%)	I	15.9	(1.2)	21.5^a	3.0^c	15.3^ab	10.3^bc	(9.9)	^*	49.4	49.4	(4.6)
	IIA	13.1	(1.7)	26.5^a	18.5^ab	5.8^c	17.5^b	(4.6)	^***	33.2^a	19.8^b	(3.4)	^***
	IIAX	1.0	(0.7)	2.0	nd	2.7	2.9	(1.3)		nd	2.3	(1.4)
	IIX	50.6	(3.1)	14.5	26.8	22.9	21.3	(7.8)		9.4	18.1	(7.2)
	IIXB	9.7	(0.8)	24.4^a	19.7^a	2.3^b	22.6^a	(8.1)	^*	8.0	7.4	(5.2)
	IIB	9.7	(3.9)	10.7^b	32.0^ab	51.0^a	25.4^b	(10.5)	^***	nd	3.1	(2.2)
Fiber density (number/mm²)	I	38.9	(1.8)	49.8^a	8.3^b	57.6^a	52.9^a	(25.9)	^**	111.8	135.2	(18.5)
	IIA	32.9	(2.7)	71.3^b	59.7^bc	34.3^c	113.2^a	(15.6)	^***	83.5	74.3	(10.8)
	IIAX	2.2	(1.5)	5.0^b	nd	15.1^a	17.6^a	(5.4)	^*	nd	6.9	(4.1)
	IIX	128.7	(13.7)	42.3^c	82.9^b	102.3^a	86.4^ab	(25.0)	^*	23.6	43.9	(15.6)
	IIXB	33.1	(1.4)	57.7^a	59.2^a	8.9^b	81.0^a	(23.4)	^*	19.5	23.3	(14.6)
	IIB	26.1	(11.4)	24.2^b	116.5^a	157.7^a	101.3^a	(33.3)	^***	nd	9.4	(6.1)
	Total	261.9	(16.3)	251.3^c	326.6^bc	375.8^ab	452.4^a	(42.9)	^***	238.3	292.9	(23.8)

Data are means and pooled SE (PE).
Significant differences (p<0.05) between muscle types within the same parallel structural subtype are indicated with different superscripts.
p<0.05,
p<0.01,
p<0.001.
GR, M. gracilis; PM, M. psoas major; ST, M. semitendinosus; SM, M. semimembranosus; VT, M. vastus; IF, M. infrahyoid; RA, M. rectus abdominis; nd, not detected.