The effect of muscle training is dependent on both genetic and environmental factors. We demonstrated the effect of genetic factors on muscle training using some inbred mouse strains which show a coefficient of inbreeding of more than 98%. Experiments on these mice have shown that genetic factors are mainly responsible for the induction of skeletal muscle hypertrophy. On the basis of this finding, we focused on the effect of environmental factors on the induction of skeletal muscle hypertrophy using tenotomy. Six-week-old inbred NZW/N, NZB/N and A/J were used. Muscles (soleus and plantaris) were removed on the 7th day after the operation, and wet weight was measured with an electronic balance.
　Although the Weight of the plantaris muscle in NZW/N mice increased higher rate than in NZB/N mice, we were unable to observe any difference in the rate for the muscle between the two strains (P< 0.05) . Measurement of Mute increase of muscle weight after the experiment showed that those of the soleus and plantaris muscles in NZW/N mice higher than in NZB/N mice. Furthermore, the mean balance of plantaris muscle weight in NZW/N mice was significantly higher than in A/J mice

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