Executive functions, self-paced exercise and cycling performance

Abstract

The main aim of the present thesis was to understand the role of executive (cognitive) functions in self-paced aerobic exercise (cycling). A self-paced exercise is a physical activity in which the effort has to be distributed in the best possible way to achieve the objective of the event (e.g., to cover a given distance as quickly as possible or to cover the largest possible distance in a given time) (1,2). Self-paced exercise requires the monitoring and control of feedback from the muscles and cardiorespiratory systems to the brain (3).. From an applied point of view, we could consider that the self-paced aerobic exercise is a goal-directed behaviour towards an objective that involves several cognitive processes, and in particular of executive functions (e.g., inhibitory control or working memory) (18). Consequently, any change at cognitive level (and brain related to the cognitive processes under study) will affect physical performance. To understand this relationship, in an introductory chapter we summarized the role of executive functions on the self-paced exercise, and the empirical evidence of the neural basis. We also summarized the different manipulations that have been designed to investigate the role of the executive functions on self-paced exercise. In the following chapters, we describe the three studies we have conducted to investigate the role of executive functioning on the self-paced exercise. First, we investigated the ergogenic effect of tramadol on physical and cognitive performance. Next, we attempt to understand the effects of transcranial direct current stimulation (tDCS) (applied to the left dorsolateral prefrontal cortex) on objective and subjective indices of exercise performance. Finally, we investigated the role of cognitive (executive) load during self-paced exercise. Analgesics drugs are widely used in sports to treat pain and anti-inflammatory processes associated with injuries (4). However, it has been detected that there is a tendency among athletes of all levels to use these drugs, not only to treat minor injuries, but also to train and compete (5). Therefore, in addition to its peripheral effects, there is a possibility that athletes are using these drugs for their effects in the central nervous system to increase physical performance during training and competitions. Some of these drugs could have an effect on the activation of higher brain structures (e.g., prefrontal cortex or anterior cingulate cortex) involved in pain and cognitive processing.

El principal objetivo de la presente tesis doctoral era entender el rol de las funciones ejecutivas (cognitivas) en el ejercicio aeróbico autorregulado (ciclismo). El ejercicio autorregulado es una actividad física en la que el esfuerzo tiene que ser distribuido de la mejor manera posible para alcanzar el objetivo de la prueba (ej., cubrir una distancia los más rápido posible o cubrir la mayor distancia posible en un tiempo dado) (1,2). La autorregulación del esfuerzo físico requiere de la monitorización y control del feedback procedente de los músculos y sistemas cardiorrespiratorio hacía el cerebro (3). Desde un punto de vista aplicado, podríamos considerar que el ejercicio aeróbico autorregulado es un comportamiento dirigido hacia un objetivo que involucra varios procesos cognitivos, y en particular de funciones ejecutivas (ej., control inhibitorio o memoria de trabajo) . En consecuencia, cualquier cambio a nivel cognitivo (y cerebral relacionado con los procesos cognitivos objeto de estudio) afectará al rendimiento físico. Los analgésicos son fármacos ampliamente utilizados en el deporte para tratar el dolor y procesos antiinflamatorios asociados con las lesiones (4). Sin embargo, se ha detectado que existe una tendencia entre los atletas de todos los niveles a usar estos fármacos analgésicos, no solo para tratar lesiones menores, sino que también para entrenar y competir (5). Por lo tanto, además de por sus efectos periféricos, existe la posibilidad de que los atletas estén usando estos fármacos por sus efectos a nivel de sistema nervioso central para incrementar el rendimiento físico durante los entrenamientos y competiciones. Algunos de estos fármacos podrían tener un efecto sobre la activación de estructuras cerebrales superiores (por ejemplo, la corteza prefrontal o la corteza cingulada anterior) involucradas en el dolor y el procesamiento cognitivo.