Table 1.

Distributions of slack lengths and pennations of muscle fascicles from the medial and lateral gastrocnemius muscles

	Both medial and lateral gastrocnemius			Medial gastrocnemius			Lateral gastrocnemius
	Mean	SD	n	mean	SD	n	Mean	SD	n
lg(FSL) (%)a	33	7	142	33	7	85	33	7	57
lf(FSL) (mm)b	40	8	142	39	8	85	43	8	57
2-D pennation (deg)c	17	6	159	19	6	93	14	3	66

Data are from 10 subjects.

^aMuscle–tendon length at which fascicles fall slack, expressed as a percentage of the in vivo range of lengths.

^bFascicle slack length, in mm.

^cTwo-dimensional pennation. It was not always possible to detect slack lengths so there are fewer observations for slack lengths than for pennation.