Relação da dose resposta do exercício físico aeróbio sobre os sintomas de ansiedade estado de adultos jovens: um ensaio clínico randomizado e cruzado

Abstract

Anxiety can be a normal emotion or become pathological, characterized by excessive worry, anticipatory distress, and fear. In the latter case, anxiety symptoms can interfere with quality of life, particularly in terms of interpersonal relationships and self-fulfillment. The lifetime risk of developing an anxiety disorder exceeds 25%, making anxiety disorders one of the most prevalent psychiatric conditions and a leading cause of years of life lost due to disability or premature death worldwide. Of particular interest to the present study, aerobic exercise has been identified as an effective non-pharmacological tool for preventing and treating anxiety symptoms. Moreover, most studies evaluating the acute effect of aerobic exercise on anxiety symptoms have employed a variety of intensities, with no clear consensus on the optimal intensity for managing state anxiety symptoms. One of the factors influencing studies on the acute effects of aerobic exercise on state anxiety symptoms is the floor effect, where pre-exercise state anxiety symptoms are classified as mild. To address this, previous investigations have used methods to experimentally increase state anxiety symptoms. The advantage of this approach is that it allows for accuracy control of the intensity and duration of the anxiogenic stimulus. Objective: To investigate the dose-response relationship of acute aerobic exercise performed on a treadmill at different domains intensity (light, moderate, and vigorous) on state anxiety symptoms in healthy young individuals of both sexes, who were previously exposed to anxiogenic stimuli. Methods: This was a randomized crossover clinical trial. The sample consisted of 77 participants (39 women) with a median age of 25.53 years. The study was divided into five stages, conducted on separate days (48-96h). The first stage included a detailed explanation of the research, signing of the informed consent form, general anamnesis, assessment of trait anxiety symptoms, and cardiorespiratory fitness evaluation. The subsequent stages consisted of aerobic exercise sessions at light, moderate, and vigorous intensities on a treadmill, as well as a control session involving rest without exercise. The order of sessions was determined through counterbalanced randomization. The aerobic exercise sessions included a 5-minute warm-up at 3.8 km/h, a 30-minute main phase, and a cool-down phase with the same speed and Abstract xvi duration as the warm-up, totaling 40 minutes. The control session, consisting of rest without exercise, also lasted 40 minutes. The prescription of aerobic exercise was based on the percentage of each participant’s maximum heart rate achieved during the cardiorespiratory fitness assessment. State anxiety symptoms were assessed before exposure to unpleasant images, after exposure to unpleasant images, and after both the aerobic exercise and control sessions using the State-Trait Anxiety Inventory. For statistical analysis, a linear mixed model was used to compare the acute effects of treadmill aerobic exercise performed at different domains intensity on state anxiety symptoms. Results: Statistical analysis provided strong evidence of an interaction between time and session (F = 4.812; p-value < 0.001; ηp² = 0.051, small effect size) on participants’ state anxiety symptoms. Holm’s post hoc test revealed moderate evidence that light-intensity aerobic exercise (z = 3.187; p-value = 0.010) was superior to the control session, very strong evidence that moderateintensity aerobic exercise (z = 4.678; p-value < 0.001) was superior to the control session, and strong evidence that vigorous-intensity aerobic exercise (z = 3.470; pvalue = 0.004) was superior to the control session in reducing state anxiety symptoms induced by unpleasant images. Additionally, Holm’s post hoc test showed no differences between the three aerobic exercise intensities in reducing state anxiety symptoms. Statistical analysis also revealed no differences in the anxiolytic response elicited by different aerobic exercise intensities between sexes. Conclusions: Treadmill aerobic exercise sessions at light, moderate, and vigorous intensities were effective in reducing state anxiety symptoms following exposure to unpleasant images compared to the control session, with no differences between intensities. This indicates that there was no dose-response relationship between aerobic exercise intensity and the reduction of state anxiety symptoms. Furthermore, this effect was consistent across both sexes. These findings highlight the role of treadmill aerobic exercise as a viable strategy for managing anxiety symptoms, regardless of sex or exercise intensity. Therefore, health professionals can advise young and healthy individuals to perform aerobic exercise on a treadmill without the need for advice on a specific intensity of physical exercise.