TY - JOUR
T1 - How physical exercise changes rat myotendinous junctions
T2 - An ultrastructural study
AU - Curzi, D.
AU - Salucci, S.
AU - Marini, M.
AU - Esposito, F.
AU - Agnello, L.
AU - Veicsteinas, A.
AU - Burattini, S.
AU - Falcieri, E.
PY - 2012
Y1 - 2012
N2 - Myotendinous junctions (MTJ) can be easily injured by overloading or trauma, and exercise training may be a way of increasing their resistance to mechanical stress. To this end, we examined herein the morphological changes induced by moderate exercise training in the MTJ of extensor digitorum longus (EDL) and gastrocnemius muscles in rats. Twelve Sprague-Dawley rats were used in this investigation. Six of them were trained to run on a treadmill for 1 h/day, 3 days/week over 10 weeks in order for them to achieve a running rate of 25 m/min at the end of the training period. Six agematched sedentary rats were used as controls. The rats were sacrificed 24 h after the final training session, and the EDL and the gastrocnemium were excised; the MTJ were then prepared and observed with electron microscopy. Digitation branching was evaluated by counting the bifurcations in the MTJ protrusions. Our observations indicate that exercise does indeed induce changes in MTJ morphology. In both muscles the number of bifurcated interdigitations increased significantly, as well as, in gastrocnemius, the branching of the finger-like processes. It was demonstrated that the MTJ is able to adapt to an increase in tensile force by enlarging the muscle-tendon contact area and, consequently, mechanical resistance.
AB - Myotendinous junctions (MTJ) can be easily injured by overloading or trauma, and exercise training may be a way of increasing their resistance to mechanical stress. To this end, we examined herein the morphological changes induced by moderate exercise training in the MTJ of extensor digitorum longus (EDL) and gastrocnemius muscles in rats. Twelve Sprague-Dawley rats were used in this investigation. Six of them were trained to run on a treadmill for 1 h/day, 3 days/week over 10 weeks in order for them to achieve a running rate of 25 m/min at the end of the training period. Six agematched sedentary rats were used as controls. The rats were sacrificed 24 h after the final training session, and the EDL and the gastrocnemium were excised; the MTJ were then prepared and observed with electron microscopy. Digitation branching was evaluated by counting the bifurcations in the MTJ protrusions. Our observations indicate that exercise does indeed induce changes in MTJ morphology. In both muscles the number of bifurcated interdigitations increased significantly, as well as, in gastrocnemius, the branching of the finger-like processes. It was demonstrated that the MTJ is able to adapt to an increase in tensile force by enlarging the muscle-tendon contact area and, consequently, mechanical resistance.
KW - Exercise
KW - Myotendinous junctions
KW - Skeletal muscle
KW - Tendon
KW - Tension
KW - Training
KW - Ultrastructure
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U2 - 10.4081/ejh.2012.e19
DO - 10.4081/ejh.2012.e19
M3 - Article
AN - SCOPUS:84859837000
VL - 56
SP - 117
EP - 122
JO - European Journal of Histochemistry
JF - European Journal of Histochemistry
SN - 1121-760X
IS - 2
ER -