Eccentric training does not increase sarcomere number in rabbit dorsiflexor muscles.

The hypothesis of this study was that eccentric muscle training induces serial sarcomere addition. Eccentric training of rabbit dorsiflexor muscles (50 maximal contractions, 2 times per week, for 12 weeks) increased sarcomere number by only 3% in superficial fascicles of the tibialis anterior (TA) and did not change sarcomere number in deep fascicles of the TA nor in proximal or distal fascicles of extensor digitorum longus. Thus eccentric training had little or no effect on sarcomere number. These results do not support previous speculation that eccentric training produces increases in sarcomere number.