Fig. 2.

Stress-strain responses (A) and tangent moduli (B) for single fibers and fiber bundles from adult and old TA muscles. At long sarcomere lengths, old muscle bundles exhibited larger stresses than old single fibers, indicating increased bundle modulus at sarcomere lengths at 2.7, 2.9, and 3.1 μm. Moduli of adult fibers and bundles were similar, and single fiber modulus was unchanged with age. *Significantly different from all other groups at a given strain (P < 0.05). Data presented as means ± SD.