Few data exist on the temporal responses of the influence of catecholamines on muscle force production in vivo. The purpose of this study was to examine the influence of the pre-exercise arousal on sympathoadrenal neurohormones on muscular force expression during resistance-exercise. Ten resistance-trained men completed two experimental conditions separated by 7 days: i) Acute Heavy Resistance Exercise Protocol (AHREP; 6 x 10 repetitions parallel squats, 80% 1RM), and ii) Control (CONT; rest). Peak force (F_peak) was recorded during a maximal isometric squat preceding each set and mean force (F_mean) was measured during each set. Serial venous blood samples were collected prior to the AHREP and immediately preceding each set. Blood collection times were matched during CONT. Pre-exercise epinephrine (EPI), norepinephrine (NE), and dopamine (DA) increased (P 0.05) above CONT 270%, 255%, and 164%, respectively. During exercise, EPI, NE, and DA continued to increase 512%, 271%, and 38%, respectively, above pre-exercise values. F_peak and F_mean decreased ~20-25% over the course of the AHREP. Post-hoc data analysis revealed 5 subjects (F_maintainers) showed no decline (P 0.05) in muscular performance (F_peak, F_mean) during AHREP and 5 subjects (F_reducers) had significant reductions in F_peak and F_mean. Integrated area under the curve (AUC) for EPI, NE, and F_peak were greater (p < 0.02) for F_maintainers than F_reducers. In conclusion, an anticipatory rise in catecholamines existed, may be essential for optimal force production at the onset of exercise.