Determining central activation failure and peripheral fatigue in the course of sustained maximal voluntary contractions: a model-based approach

• Published in: Journal of applied physiology (1985) Vol. 98; no. 6; pp. 2292 - 2297
• Main Authors: Schillings, Maartje L, Stegeman, Dick F, Zwarts, Machiel J
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.06.2005; American Physiological Society
• Subjects: Adult; Algorithms; Animals; Biological and medical sciences; Central Nervous System - physiology; Computer Simulation; Diagnosis, Computer-Assisted - methods; Electricity; Failure; Fatigue; Female; Fundamental and applied biological sciences. Psychology; Humans; Male; Models, Neurological; Muscle Contraction - physiology; Muscle Fatigue - physiology; Muscle, Skeletal - innervation; Muscle, Skeletal - physiology; Peripheral Nerves - physiology; Physical Endurance - physiology; Physical Exertion - physiology; Reproducibility of Results; Sensitivity and Specificity; Volition - physiology; Vertebrata; Mammalia; twitch interpolation technique; Electrical stimulus; central fatigue; superimposed electrical stimulation; Fatigue; Models; Muscle contraction
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.01342.2004

Department of Clinical Neurophysiology, Radboud University Nijmegen Medical Centre, Nijmegen, and Interuniversity Institute for Fundamental and Clinical Human Movement Sciences, Nijmegen, Amsterdam, The Netherlands Submitted 1 December 2004 ; accepted in final form 4 February 2005 In the study of fatigue, several methods have been used to calculate the development of central activation failure (CAF) and peripheral fatigue (PF) in the course of a sustained maximal voluntary contraction (MVC). This paper presents a model that enables simultaneous determination of CAF and PF during sustained MVC by using only force registration and superimposed electrical stimulation. In the model, we explicitly use the assumption, which is virtually always made implicitly in earlier studies, that a constant relative fraction of maximal possible force is activated by the electrical stimulation. That fraction can be determined at the start and at the end of a sustained MVC. The model shows that in the course of a sustained MVC, CAF can be calculated by merely using 1 ) this fraction, 2 ) the amplitudes of the superimposed force responses to stimulation, and 3 ) the course of voluntary force. After CAF quantification, the development of PF during MVC becomes available as well. The present study first examines the model assumption with data of sustained MVCs of variable durations on six healthy subjects. Subsequently, it shows CAF values in a group of 27 healthy subjects determined with both the model and a method of linear interpolation for PF estimation. Model-based CAF values were significantly higher during, but not at the start and at the end of, a 2-min sustained MVC. Next to a well-justified CAF determination, the model has the advantage of simultaneously quantifying PF, which was not possible with the previous methods. central fatigue; twitch interpolation technique; superimposed electrical stimulation Address for reprint requests and other correspondence: D. F. Stegeman, Radboud Univ. Nijmegen Medical Centre, Dept. of Clinical Neurophysiology, Internal postal code: 314, PO Box 9101, 6500 HB Nijmegen, The Netherlands (E-mail: D.Stegeman{at}neuro.umcn.nl )