The Effect of Aging on Skeletal Mechanoresponsiveness: Animal Studies - Skeletal Aging and Osteoporosis: Biomechanics and Mechanobiology - page 200

Table 3 Summary of studies that examined the influence of age on bone responses to extrinsic cyclic loading

Study Animal sex,

species (Strain)

Age Protocol Significant observations regarding

the influence of loading

Conclusion

Rubin et al.
[ 37 ]

Male, Turkey 12 months—young

36 months—old

Ulna isolation, axial loading, 8 weeks,
300 cycles/day, 3000 le,2Hz

Cortical area: Y :
Mineral apposition rate: Y :

Age effect;
old not
responsive

Turner et al.
[ 44 , 45 ]

Female, rat
(Sprague-
Dawley)

9 months—mature
19 months—old

Tibial 4-point bending, 2 weeks, 36
cycles/day, 2 Hz
Mature: 27-64 N (1400-3000 le)
Old: 30-64 N (1600-3100 le)

Periosteal woven bone formation
load [40 N: M: (100%),
O: (60%)
Endocortical lamellar bone
formation
load 40 N: M:; load 64 N: M::,
O:

Age effect;
old less
responsive

4 months—young a
21 months—old

Srinivasan
et al.
[ 53 ]

Female, mice
(C57Bl/6)

Tibial cantilever bending, 2 weeks,
50-250 cycles/day, 1200-2400 le,
1 s load±10 s rest

Bone formation rate: Y::,O:
(O is 2.5-fold less than Y)
O: rest insertion increases bone
formation similar to doubling of
strain

Age effect;
old less
responsive

Kesavan
et al.
[ 46 ]

Female, mice
(C57Bl/6,
C3H/He)

2 months, 4
months—young
8 months—
mature

Tibial 4-point bending, 2 weeks,
36 cycles/day, 9 N (*3800 le), 2 Hz

Cross sectional area: Y:,M:
BMC: Y:,M:

No age effect

Silva and
Brodt
[ 51 ]

Male, mice
(SAM)

4 months
SAMP6 (senescent)
SAMR1 (control)

Tibial 3-point bending, 2 weeks,
60 cycles/day, 1000-2000 le
endocortical,
0.5 s load ? 10 s rest

Endocortical bone formation:
SAMR1:, SAMP6:

No effect of
''senescence''

(continued)