Muscular activity and torque of the foot dorsiflexor muscles during decremental isometric test: A cross-sectional study.
OBJECTIVE
To analyse the torque variation level that could be explained by the muscle activation (EMG) amplitude of the three major foot dorsiflexor muscles (tibialis anterior (TA), extensor digitorum longus (EDL), extensor hallucis longus (EHL)) during isometric foot dorsiflexion at different intensities.


METHODS
In a cross-sectional study, forty-one subjects performed foot dorsiflexion at 100%, 75%, 50% and 25% of maximal voluntary contractions (MVC) with the hip and knee flexed 90° and the ankle in neutral position (90° between leg and foot). Three foot dorsiflexions were performed for each intensity. Outcome variables were: maximum (100% MVC) and relative torque (75%, 50%, 25% MVC), maximum and relative EMG amplitude. A linear regression analysis was calculated for each intensity of the isometric foot dorsiflexion.


RESULTS
The degree of torque variation (dependent variable) from the independent variables explain (EMG amplitude of the three major foot dorsiflexor muscles) the increases when the foot dorsiflexion intensity is increased, with values of R2that range from 0.194 (during 25% MVC) to 0.753 (during 100% MVC). The reliability of the outcome variables was excellent.


CONCLUSIONS
The EMG amplitude of the three main foot dorsiflexors exhibited more variance in the dependent variable (torque) when foot dorsiflexion intensity increases.
Universidad de Málaga, Departamento de Enfermería y Podología, Instituto de Investigación Biomédica de Málaga (IBIMA), Málaga, Spain. Electronic address: marumu@uma.es.
Maria
M
Ruiz-Muñoz
Universidad de Jaén, Departamento de Ciencias de la Salud, Jaén, Spain. Electronic address: mgsa23@uma.es.
Manuel
M
González-Sánchez
Universidad de Málaga, Departamento de Fisioterapia. Instituto de Investigación Biomédica de Málaga (IBIMA); Escuela de Terapia Ocupacional, Facultad de Salud, Deporte y Recreación, Universidad Bernardo ÓHiggins, Santiago de Chile, Chile. Electronic address: jaimemartinmartin@gmail.com.
Jaime
J
Martín-Martín
Universidad de Málaga, Departamento de Fisioterapia. Instituto de Investigación Biomédica de Málaga (IBIMA); School of Clinical Sciences at Queensland University, Brisbane, Australia. Electronic address: acuesta.var@gmail.com.
Antonio I
AI
Cuesta-Vargas
D000328:Adult; D000843:Ankle Joint / Q000502:physiology*; D003430:Cross-Sectional Studies; D004576:Electromyography; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology*; D012680:Sensitivity and Specificity; D019415:Torque; D055815:Young Adult
Ankle; Electromyography; Extensor digitorum longus; Extensor hallucis longus; Force; Tibialis anterior