This study employed a randomized crossover design to assess the impacts of three different experimental conditions-standard environment, music, and verbal encouragement-on performance in an isometric endurance task, with comparisons made between untrained and trained individuals. Interventions were spaced seven days apart. Measurements included muscle activity and fatigue, assessed via surface electromyography, and the duration of the task.

The isometric endurance task required participants to maintain a 90° elbow flexion while holding a dumbbell in a supine grip, weighted to 80% of their one-repetition maximum, on the dominant side. During the task, participants were to keep their back and head against a vertical wall, stand with feet shoulder-width apart, and firmly on the ground. The dumbbell was held with the dominant arm, and the other arm was kept neutral by the side. It was crucial to avoid any rocking or movements that would ease maintaining the position. The test began when the bar was handed to the participant in the correct stance and concluded once the arm's angle deviated by more than five degrees from the start.

Inclusion Criteria:

• Good general health,
• No medical conditions that could interfere with their ability to perform the test safely and effectively.
• To be considered exercised, participants had to have performed 150 minutes per week of vigorous intensity aerobic physical activity, in addition to muscle strengthening activities, for at least two days per week. Those who did not meet this standard were considered untrained.

Exclusion Criteria:

• History of surgery on the arm, shoulder or adjacent areas that could limit the ability to perform the test.
• Use of medication that affects muscle function or pain perception