Research article - (2007)06, 106 - 116
Assessment of the Quadriceps Femoris Muscle in Women after Injury Induced by Maximal Eccentric Isokinetic Exercise with Low Angular Speed
Fábio Viadanna Serráo1,, Paula Regina Mendes da Silva Serráo1, Bernd Foerster2, Alberto Tannús2, Vanessa Monteiro Pedro1, Tania F. Salvini
1Department of Physical Therapy - Federal University of São Carlos, São Carlos, SP, Brazil
2Institute of Physics of São Carlos, São Paulo University, São Carlos, SP, Brazil

Fábio Viadanna Serráo
✉ Departamento de Fisioterapia, Universidade Federal de São Carlos – UFSCar, Rod. Washington Luís, Km 235, CEP: 13565-905, São Carlos – SP – Brasil
Email: fserrao@power.ufscar.br
Received: 04-09-2006 -- Accepted: 24-01-2007
Published (online): 01-03-2007

ABSTRACT

The objectives of this study were to propose a model for exercise- induced muscle injury by way of a maximal eccentric isokinetic exercise at low angular speed, and assess the time course of functional recovery of the injured quadriceps femoris muscle from the maximal voluntary contraction (MVC) torque and electrical activity (root mean square - RMS and median frequency - MDF). The effectiveness of the proposed eccentric exercise in inducing injury was assessed from the activity of creatine kinase (CK). In addition, the presence of edema of the quadriceps femoris muscle was assessed by a visual inspection of the intensity of the magnetic resonance imaging (MRI) signal. These measurements were carried out before and after the exercise. Ten healthy women (21.9 ± 1.5) took part in this study. The injury was induced by 4 series of 15 maximal eccentric isokinetic contractions at 5°/s. The MVC torque reduced up to the 4th day after the exercise (p < 0.05). The RMS of the vastus medialis oblique (VMO) and the rectus femoris (RF) muscles decreased on the 2nd (VMO and RF; p < 0.05) and 3rd (RF; p < 0.05) days after. The MDF of the VMO increased immediately after (p < 0.05), whilst the MDF of the RF and VL decreased immediately after (RF; p < 0.05), on the 1st (RF and VL; p < 0.05) and on the 2nd (VL; p < 0.05) days after. The CK activity increased on the 2nd day after (p < 0.05). An increase in the intensity of the MRI signal was observed on the 2nd and 7th days after. In conclusion: 1- the eccentric exercise with low angular speed was effective in inducing injury, 2- the quadriceps femoris already started its functional recovery, as shown by the MVC torque and electrical activity, in the first week after the exercise, despite the presence of an increase in the intensity of the MRI signal.

Key words: Muscle damage, torque, electromyography, magnetic resonance imaging, creatine kinase

Key Points
  • The low angular speed eccentric exercise was effec-tive in inducing injury of the quadriceps femoris muscle, and could be used as a muscle injury induc-ing model in future studies;
  • The quadriceps femoris muscle injured by eccentric exercise started its functional recovery in the first week after low angular speed eccentric exercise.








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