The effects of motivational verbal phrases on isoinertial force production and sustained force output: a comparison of positive and negative conditions

Abstract

Introduction: This study aimed to compare the effects of positive and negative motivational verbal phrases applied during short-term maximal isoinertial squat exercise on force production, sustained force output, and perceived exercise difficulty. Methods: Forty healthy university students (20 women and 20 men) from the Faculty of Sports Sciences voluntarily participated in this randomized crossover study. Each participant completed a 30-s maximal isoinertial squat test under three experimental conditions-silent (control), positive, and negative motivational verbal phrases-across three separate sessions. Verbal stimuli were delivered at the onset of the test and every 5 s thereafter at a standardized sound intensity of 60-70 dB. Maximal force, average force, and perceived exertion (Borg RPE) were recorded. Due to violations of normality assumptions, data were analyzed using Friedman and Wilcoxon signed-rank tests with Holm-Bonferroni correction. Results: Both positive and negative motivational verbal phrase conditions resulted in significantly greater maximal and average force output compared with the silent condition (p < 0.001). Force output was significantly higher under the negative motivational verbal phrase condition than under the positive condition. However, perceived exercise difficulty was also significantly elevated during negative motivational verbal phrase exposure (p < 0.01). No significant sex-based differences were observed in responses to motivational verbal phrases. Discussion: These findings demonstrate that not only the presence but also the content and emotional valence of motivational verbal phrases play an important role in short-term maximal strength performance and perceptual responses. Negative motivational verbal phrases may enhance force output, albeit at the cost of increased perceived exertion, highlighting the need for deliberate and context-specific use of verbal strategies in performance testing and training environments.