Table 2.
Mechanical Properties of the mouse tibia following 5-weeks of exercise.
| 8 weeks |
13 weeks |
36 weeks |
41 weeks |
Main effects |
|||||
|---|---|---|---|---|---|---|---|---|---|
| Baseline avg (std.) | Sedentary avg (std.) | Exercise avg (std.) | Baseline avg (std.) | Sedentary avg (std.) | Exercise avg (std.) | Age (p) | Ex (p) | Int (p) | |
| Structural-level properties | |||||||||
| Yield load (N) | 13.5 (3.0) | 16.1 (3.3) | 18.2 (3.3) | 12.4 (3.5) | 11.5 (2.7)a | 12.0 (3.2)a | <0.001 | ||
| Yield displacement (μm) | 240.6 (68) | 238.8 (41) | 261.0 (74) | 214.7 (34) | 196.8 (40) | 211.9 (72)a | <0.01 | ||
| Ultimate load (N) | 16.6 (3.5) | 17.6 (2.9) | 19.6 (3.2) | 13.1 (3.3)c | 13.5 (3.2)a | 13.9 (2.6)a | <0.001 | ||
| Ultimate displacement (μm) | 392.8 (95) | 330.9 (125) | 335.1 (109) | 254.1 (38)c | 302.0 (66) | 285.7 (61) | |||
| Stiffness (N/mm) | 70.6 (18) | 83.4 (19) | 87.1 (22) | 69.5 (16) | 75.5 (16) | 67.8 (19)a | <0.05 | ||
| Tissue-level properties | |||||||||
| Yield stress (MPa) | 164.9 (31) | 167.2 (51) | 205.2 (49) | 110.5 (40)c | 117.2 (34)a | 97.8 (40)a | <0.001 | ||
| Yield strain (με) | 23,804 (5208) | 22,732 (4007) | 25,668 (7091) | 20,195 (3581)c | 18,273 (3363) | 21,327 (8007) | <0.01 | <0.05 | |
| Ultimate stress (MPa) | 203.9 (36) | 183.9 (42) | 221.1 (50)b | 117.6 (41)c | 136.8 (39)a | 112.6 (36)a | <0.001 | <0.05 | |
| Ultimate strain (με) | 39,664 (9827) | 31,582 (10,385) | 33,361 (12,256) | 23,929 (4316)c | 28,268 (6737) | 28,733 (6820) | |||
| Modulus (GPa) | 8.65 (2.2) | 9.14 (3.1) | 9.79 (3.3) | 6.62 (2.3) | 8.23 (2.3) | 5.39 (1.4)b | <0.01 | <0.05 | |
n = 10, Ex = Exercise, Int = Interaction between exercise and age.
a
p-value < 0.05 compared to 13-week old control.
b
p-value < 0.05 compared to sedentary control within same age-group;
c
p-value < 0.05 of student t-test compared to 8-week baseline group.