Figure 4: High strain rates induce plastic deformation.

a, Ratio of stress during third cycle to first cycle for cells deformed in three cycles of stress relaxation at the same rates as in Fig. 1. Stress decreases after trauma-like stretch when all three stretches are at the same rate. b-e, Cells were stretched in alternating patterns of strain rate: slow-fast-slow (black-red-black, b) and slow-trauma-slow (black-yellow-black, d). Average normalized axial PK1 stress for cells subjected to the slow-fast-slow (c) and slow-trauma-slow (e) sequences. Rate softening occurs in the slow-fast-slow stretching sequence but cells recover their stress in subsequent cycles of stretch. A single stretch at the trauma-like rate reduces stress in subsequent slow stretching sequences. n = 17, 14 cells, respectively. f, Ratio of stress during third cycle to first cycle for slow-slow-slow (black), slow-fast-slow (red), and slow-trauma-slow (yellow) strain sequences. Solid bars represent mean cycle 3 to cycle 1 ratio. Open circles are individual measurements. *p < 0.05, **p < 0.01. Error bars represent s.e.m.