Bone healing in rats submitted to weight-bearing and non-weight-bearing exercises.
BACKGROUND
To investigate the effects of low-intensity exercise on bone healing during a short time.


METHODS
We made a surgical 1-mm perforation in the upper third medial cortical of the right tibia of 45 male Wistar rats (3 months old; mean weight, 282+/-34 g). Animals were randomly assigned to a swimming exercise group (SWIM, n=15), a running exercise group (RUN, n=15), or a no exercise control group (CON, n=15). Treatment sessions (10 minutes/day, 5 days/week) were done for 7, 14, or 21 days. Tibias were removed for radiographic, morphometric, and stereologic analyses. Blood samples were obtained for biochemical analyses.


RESULTS
Serum phosphorus levels were higher in animals in the RUN group compared with animals in the SWIM group on the seventh day. On the 14th day, the tibias of the animals in the SWIM and RUN groups exhibited higher radiopacity in radiographic grades than animals in the CON group. No difference in collagen morphometry was verified. On the 21st day, serum alkaline phosphatase levels were higher in animals in the CON group than they were in the exercise groups, and animals in the SWIM and CON groups demonstrated an increase in newly formed bone in comparison to animals in the RUN group.


CONCLUSIONS
At the 14th day of treatment, weight-bearing exercise, assessed by radiography, was found to be beneficial for bone healing. Results at the 21st day of treatment further supported the benefits of non-weight-bearing exercises, showing that weight-bearing exercise may improve bone repair in rats.
Rueff-Barroso
Carlos Romualdo
CR
Tissue Repair Laboratory, Department of Histology and Embryology, Rio de Janeiro State University, Brazil.
Milagres
Débora
D
do Valle
Juliana
J
Casimiro-Lopes
Gustavo
G
Nogueira-Neto
José Firmino
JF
Zanier
José Fernando Cardona
JF
Porto
Luis Cristóvão
LC
D000818:Animals; D001835:Body Weight; D001842:Bone and Bones / Q000293:injuries* / Q000378:metabolism; D017102:Fracture Healing; D008297:Male; D010805:Physical Conditioning, Animal; D051381:Rats; D017208:Rats, Wistar; D016474:Weight-Bearing