Background: this study aimed to identify the influence of postural stability on upper-limb bilateral deficit (BLD), and to compare the assessment of strength generated during elbow flexion functionally vs. analytically in the dominant and nondominant arms. Methods: Twenty men participated in two sessions to evaluate the maximum isometric strength of elbow flexion. This evaluation was performed unilaterally with the dominant arm, unilaterally with the non-dominant arm, and bilaterally, both in the sitting position (SiP) and the standing position (StP). Results: The BLD when peak force was considered was lower for StP (-6.44 +/- 5.58%) compared to SiP (-10.73 +/- 6.17%) (p = 0.007). Regarding peak force, statistically significant differences were observed for comparisons between dominance (p < 0.001) and Position*Dominance (p = 0.02), but mean force differences were only observed for the dominance factor (p < 0.001). Greater mean and peak forces were always produced bilaterally compared to unilaterally (p < 0.001). Conclusions: a decrease in postural stability by performing elbow flexion exercises in a standing position accentuates BLD of peak force.