Effect of controlled exercise on middle gluteal muscle fibre composition in Thoroughbred foals.
BACKGROUND
Most racehorses are trained regularly from about age 18 months; therefore, little information is available on the effect of training in Thoroughbred foals.


OBJECTIVE
Well-controlled exercise could improve muscle potential ability for endurance running.


METHODS
Thoroughbred foals at age 2 months were separated into control and training (treadmill exercise) groups and samples obtained from the middle gluteal muscle at 2 and 12 months post partum. Muscle fibre compositions were determined by histochemical and electrophoretical techniques and succinic dehydrogenase (SDH) activity was analysed in each fibre type.


RESULTS
All fibre types were hypertrophied with growth and type I and IIA fibres were significantly larger in the training than the control group at age 12 months. A significant increase of SDH activity was found in type IIX muscle fibres in the training group.


CONCLUSIONS
Training in young Thoroughbred horses can facilitate muscle fibre hypertrophy and increase the oxidative capacity of type IIX fibres, which could potentially enhance stamina at high speeds.


CONCLUSIONS
To apply this result to practical training, further studies are needed to determine more effective and safe intensities of controlled exercise.
Eto
D
D
Equine Research Institute, Japan Racing Association, 321-4 Tokami-cho, Utsunomiya, Tochigi 320-0811, Japan.
Yamano
S
S
Kasashima
Y
Y
Sugiura
T
T
Nasu
T
T
Tokuriki
M
M
Miyata
H
H
D000818:Animals; D000831:Animals, Newborn / Q000033:anatomy & histology* / Q000254:growth & development / Q000502:physiology; D002081:Buttocks; D004576:Electromyography / Q000662:veterinary; D005260:Female; D006651:Histocytochemistry / Q000662:veterinary; D006736:Horses / Q000033:anatomy & histology* / Q000254:growth & development / Q000502:physiology; D008297:Male; D018656:Muscle Fibers, Fast-Twitch / Q000201:enzymology / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000201:enzymology / Q000502:physiology*; D018657:Muscle Fibers, Slow-Twitch / Q000201:enzymology / Q000502:physiology; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000254:growth & development / Q000502:physiology; D010805:Physical Conditioning, Animal / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology; D011897:Random Allocation; D013385:Succinate Dehydrogenase / Q000378:metabolism
D013385:Succinate Dehydrogenase