|Budget Amount *help
¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1996 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1995 : ¥1,600,000 (Direct Cost : ¥1,600,000)
1.Evaluation of lower limb muscle activities in behaving rats : EMGs were recorded with wire electrodes from 14 lower limb muscles of behaving rats. Tonic muscle activities usually accompanied bipedal and quadrupedal stance. During feeding in the crouched position, in particular, relatively weak, but fairy stable activities persisted for a considerable period. Based on these findings, a method was devised to normalize the EMG magnitude obtained in the behaving rats, i.e.the root mean square (RMS) of the EGM obtained during a given behavior was divided by the RMS of the EMG in the crouched feeding.
2.Lower limb muscle activities in bipedal standing rats : EMGs were recorded from 14 lower limb muscles of rats during dipedal standing trained by operant conditioning. In muscles around the hip and thigh, the highest activities appeared when the animal assumed a fully upright bipedal posture, with the hip, knee, and ankle joints extended almost to the extreme. The relative RMS as defined abov
e was largest in the semimembranosus, followed in the decreasing order by the biceps femoris, semitendinosus, gluteus medius, adductores, gluteus superficialis, vastus lateralis, gastrocnemius, tensor fasciae latae, gluteus minimus, rectus femoris, soleus, tibialis anterior, and quadratus femoris muscles. Considering the relative RMS values, assumed postures, and the muscular dispositions together with the morphological change of the femoral cross-section in response to bipedal standing exercise as previously reported by us, the present results appear to evidence involvement of the antigravitational acitivity of specific muscles in the morphological adaptation of bones.
3.Influence of bipedal standing exercise in rats on lower limb muscle weight and fiber composition : Comparison of the relative weight (vs.body weight) of 28 lower limb mscles between the rats administered with bipedal standing exercises in adolescent stage and controls revealed a tendency in the former to be greater in the biceps femoris, semitendinosus, adductores, and gluteus superficialis muscles. Muscle fiber diameters also showed the same trend as above. In the biceps femoris muscle in which the relative weight increased most markedly, FOG fibers tended to increase in response to the bipedal loading, which was particularly marked in the lateral portion. Less