. 2021 Sep 28;12:727585. doi: 10.3389/fphys.2021.727585

TABLE 1.

Single fiber characteristics for DIAm Force Model.

Fiber type	Fatigue index	Contribution to total DIAm volume (%) 6-month	Maximum specific force (N/cm²) 6-month	Residual specific force (N/cm²) 6-month	Contribution to total DIAm volume (%) 24-month	Maximum specific force (N/cm²) 24-month	Residual specific force (N/cm²) 24-month
Type I	0.8^a	14	20^b	16^d	28	20	16^d
Type IIa	0.8^a	14	24^b	19^d	21	24	19^d
Type IIx/IIb	0.1^a	72	33^b	3^d	51	23^c	2^d

^aFatigue index based on past reports for DIAm motor units (Fournier and Sieck, 1988).

^bSpecific force data from DIAm single fibers was published previously (Geiger et al., 2000, 2001a, 2002).

^cDerived from observed reductions in total MyHC expression, and attributed to the vulnerable type IIx/IIb fibers (Elliott et al., 2016).

^dResidual specific forces following fatigue calculated from values derived from a, b, and c.