Carlos Cruz-Montecinos1,2, Joaquín Calatayud3,4, Carolina Iturriaga1, Claudio Bustos1, Benjamín Mena1, Vanesa España-Romero5, Felipe P Carpes6. 1. Laboratory of Clinical Biomechanics, Department of Physical Therapy, Faculty of Medicine, University of Chile, Santiago, Chile. 2. Laboratory of Biomechanics and Kinesiology, Hospital San José, Santiago, Chile. 3. Exercise Intervention for Health Research Group, Department of Physiotherapy, University of Valencia, Valencia, Spain. joaquin.calatayud@uv.es. 4. National Research Centre for the Working Environment, Copenhagen, Denmark. joaquin.calatayud@uv.es. 5. Department of Physical Education, School of Education, Universidad de Cádiz, Cádiz, Spain. 6. Laboratory of Neuromechanics, Health Sciences Center, Universidade Federal do Pampa, Uruguaiana, Brazil.
Abstract
PURPOSE: To determine the effects of performing a self-regulated cognitive dual task on time to failure and neuromuscular force control during submaximal isometric contractions. METHODS: Fifteen young sedentary males performed isometric contractions at 50% of each individual's maximal voluntary contraction (MVC) under single-task (without cognitive load) and dual-task (with self-regulated mathematical task) conditions. Force signal complexity and biceps brachialis muscle activity were determined at the start, middle, and end of each trial. The slope of the linear regression of median frequency determined the rate of muscle fatigue. Force-task error was established as any amplitude percentage greater or less than 50% MVC. RESULTS: The dual-task condition resulted in a 42 s longer time to failure than the single-task condition. EMG amplitude did not differ between conditions. The rate of muscle fatigue was higher in the single-task (- 0.35%/s) than the dual-task (- 0.2%/s) condition. Force signal complexity was, on average, 22% lower in the dual-task condition. The dual-task condition, as compared to the single-task condition, elicited a higher rate of force-task error below (6.37 versus 4.76%) and over (2.11 versus 1.68%) the force threshold. CONCLUSION: The dual-task condition resulted in a longer time to failure and decreased motor output complexity and fatigue rate when performing a submaximal force task. As the dual task also increased the force-task error, we suggest cognitive dual tasks as a possible strategy for delaying fatigue in sedentary young males when exerting submaximal isometric force, contributing to neuromuscular training when error in force control can be ignored.
PURPOSE: To determine the effects of performing a self-regulated cognitive dual task on time to failure and neuromuscular force control during submaximal isometric contractions. METHODS: Fifteen young sedentary males performed isometric contractions at 50% of each individual's maximal voluntary contraction (MVC) under single-task (without cognitive load) and dual-task (with self-regulated mathematical task) conditions. Force signal complexity and biceps brachialis muscle activity were determined at the start, middle, and end of each trial. The slope of the linear regression of median frequency determined the rate of muscle fatigue. Force-task error was established as any amplitude percentage greater or less than 50% MVC. RESULTS: The dual-task condition resulted in a 42 s longer time to failure than the single-task condition. EMG amplitude did not differ between conditions. The rate of muscle fatigue was higher in the single-task (- 0.35%/s) than the dual-task (- 0.2%/s) condition. Force signal complexity was, on average, 22% lower in the dual-task condition. The dual-task condition, as compared to the single-task condition, elicited a higher rate of force-task error below (6.37 versus 4.76%) and over (2.11 versus 1.68%) the force threshold. CONCLUSION: The dual-task condition resulted in a longer time to failure and decreased motor output complexity and fatigue rate when performing a submaximal force task. As the dual task also increased the force-task error, we suggest cognitive dual tasks as a possible strategy for delaying fatigue in sedentary young males when exerting submaximal isometric force, contributing to neuromuscular training when error in force control can be ignored.
Entities:
Keywords:
Dissociation; Fatigue; Motor control; Muscle activity; Strength
Authors: Marcelo Bigliassi; Vinícius B Silva; Costas I Karageorghis; Jonathan M Bird; Priscila C Santos; Leandro R Altimari Journal: Physiol Behav Date: 2016-03-03