Skip Navigation LinksHome > May 2003 - Volume 35 - Issue 5 > IMPAIRMENT OF JUMPING PERFORMANCE AFTER ECCENTRIC EXERCISE D...
Medicine & Science in Sports & Exercise:
H-13K Free Communication/Poster Exercise Training

IMPAIRMENT OF JUMPING PERFORMANCE AFTER ECCENTRIC EXERCISE DEPENDS ON MYOSIN HEAVY CHAIN ISOFORM PROFILE.

Royal, I Ara1,2; Vicente-Rodríguez1, G1,2; Romero2, J García1,2; Cruz2, J R. Alvero1,2; Calbet1, J A.L.1,2

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1Department of Physical Education, University of Las Palmas de Gran Canaria. Spain.

2University of Málaga. Spain

Type II fibers are predominantly recruited during eccentric exercise.

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PURPOSE

To find out if myosin heavy chain (MHC) isoform distribution determine the magnitude of functional impairment after eccentric exercise.

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METHOD

The force generated during countermovement jumps (CMJ) was measured with a plate force before and 1h after a squat eccentric exercise session (10 series of 25 repetitions each, at 95% of maximal isometric force, measured with the knees bent at 90°) in 10 active men (25.5 ± 1.1 yr, mean ± sem). The height jump (Hj), peak force (Fp), rate of force development (RDF) and positive mechanical impulse (IMP+) were calculated from the recorded forces. The MHC isoforms and fiber type composition, and fiber size of the vastus lateralis muscle, were analysed by electrophoresis (SDS-PAGE), ATPase histochemistry and immunocytochemistry from muscle biopsies.

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RESULTS

The Hj and relative IMP+ during CMJ strongly correlated with IIa MHC isoform (r = 0.75 and r = 0.79, p = 0.05), and the relative area occupied for IIa fiber as well (r = 0.76 and r = 0.80, p = 0.05). The magnitude of HJ and IMP+ impairment 1h after the eccentric exercise was closely related with the IIa MHC percentage in vastus lateralis (both r = 0.79, p = 0.05).

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CONCLUSION

Strenuous squatting eccentric exercise reduces jumping performance, being the effect the more accentuated the higher the percentage of MHC IIa fibers. Granted by Consejo Superior de Deportes (2002).

©2003The American College of Sports Medicine

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