How can the big arm and small arm training the same thick?

Dumbbell arm extension is the fastest, practicing to tighten the fist when the small arm tense that stops the day contact, or affect the later practice 1, sitting single arm dumbbell extension: one hand lifting dumbbells over the head, so that the arm is close to the face, the control of the dumbbells slowly to the head of the other side of the shoulder to put down, to keep the elbow joints abducted. 2, supine dumbbell arm extension: lie on your back on a flat bench, feet on the ground, abdomen taut. Hold a dumbbell in each hand with a neutral grip (palms facing each other) and straighten your arms, perpendicular to your shoulders. Inhale lightly and hold your breath; bend at the elbows and slowly lower the dumbbells to the sides of your head. Keep your upper arms still as you lower the dumbbells; be careful not to let the dumbbells hit your head or shoulders, and don't let the dumbbells touch the bench at the lowest point. At the lowest point, continue to hold your breath; then straighten your arms upward and return to the starting position. Throughout the movement, keep your elbows tight toward your body and do not open outward. Exhale as you straighten your arms to the highest point; tighten your triceps forcefully for a peak contraction; then repeat the movement for the prescribed number of repetitions. Exercise volume: 3-4 sets of 8-12 reps each. Do not use too much weight, because in the process of putting the dumbbells down, if you use too much weight, you can not maintain the correct posture. 3, barbell curls: body upright, medium grip distance (the same shoulder width) positive grip barbell, hanging in front of the body. Two upper arms close to the sides of the body. Bend upward, to the biceps completely tightened, stop. Then slowly restore, do not sway back and forth during the exercise, do not use inertial force. Even if you intend to use force, the amplitude should not be too large. Negative heavy to the lowest point of the arm is not completely straight, in order to prevent elbow injuries

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