Aquatic training in menopause experimental model promote changes in the sarcomeres of the myotendinous junctions

Myotendinous junction (MTJ) is the largest area of force transmission between skeletal muscle and bone tissue, which is directly associated with physical exercise that possible promotes morphological changes in muscle and tendon tissues. The aim of this study is to describe the ultrastructural characteristics of myotendinous junction and morphometric alterations in length sarcomeres of the anterior tibial muscle of ovariectomized aged female Wistar rats submitted to a swimming protocol. Twenty aged rats with 1 year and 8 months old randomly divided into four groups (n=5): Sedentary (S); Exercised (E); Menopause (M) and Menopause Exercised (ME). The exercising protocol consists at 40 sessions, one hour daily for a two months period and overload 5 % body weight of animals with adjustments weekly measured. Histological images were analyzed by transmission electron microscopy to demonstrate morphometric characteristics and ultrastructural elements of the cellular components. From the results obtained by transmission electron microscopy ultrastructural adaptations were observed in the MTJ region. The S and M groups demonstrated tissue disorganization in addition to lower density and length of sarcoplasmatic invaginations. The E and ME groups showed greater density, length and tissue organization, besides presenting sub-levels and communications between the sarcoplasmatic projections. Besides, they present adaptations in the plasticity of the MTJ evidenced by increase in the length of the distal sarcomeres. We concluded that the MTJ region presented adaptations in relation to the physical exercise during aging associated with ovariectomy, increasing sarcoplasmatic invaginations and changing length sarcomere distal, by improving the resistance and the transmission of force in the main injured area.