Anticipatory responses of catecholamines on muscle force production

Few data exist on the temporal relationship between catecholamines and muscle force production in vivo. The purpose of this study was to examine the influence of preexercise arousal on sympathoadrenal neurohormones on muscular force expression during resistance exercise. Ten resistance-trained men completed two experimental conditions separated by 7 days: 1) acute heavy resistance exercise protocol (AHREP; 6 x 10 repetitions parallel squats, 80% 1 repetition maximum) and 2) 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 before the AHREP and immediately preceding each set. Blood collection times were matched during Cont. Preexercise epinephrine (Epi), norepinephrine (NE), and dopamine (DA) increased (P ≤ 0.05) above Cont by 270, 255, and 164%, respectively. During exercise, Epi, NE, and DA continued to increase by 512, 271, and 38%, respectively, above preexercise values. F _peak and F_mean decreased by ∼20-25% over the course of the AHREP. Post hoc data analysis revealed that five subjects (F _maintainers) showed no decline (P ≥ 0.05) in muscular performance (F_peak, F_mean) during AHREP and that five subjects (F _reducers) had significant reductions in F_peak and F _mean. Integrated area under the curve 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, which may be essential for optimal force production at the onset of exercise.