Dumbbell arms flex and stretch fastest. Stop contact on the day when the forearm is tight during boxing practice, otherwise it will affect the later practice 1. One-arm dumbbell flexion and extension in sitting position: raise the dumbbell above the head with one hand, make the arm close to the face, control the dumbbell to slowly descend to the other shoulder behind the head, and keep the elbow abduction. 2, supine dumbbell arm flexion and extension: supine on a flat stool, feet on the ground, abdomen taut. Hold dumbbells in both hands, with neutral grip (palms facing each other), arms straight and perpendicular to shoulders. Take a breath and hold your breath; Bend your elbow and slowly lower the dumbbell to the sides of your head. When putting down the dumbbell, keep the upper arm still; Be careful not to let the dumbbell hit your head or shoulders, and don't let the dumbbell hit the lowest flat stool. At the lowest point, hold your breath; Then straighten your arms and return to the starting position. During the whole exercise, the elbows should be tightened in the direction of the body, not spread out. Exhale when your arms are straight to the highest point; Tighten the triceps vigorously and do peak contraction; Then repeat this action a specified number of times. Exercise: 3-4 groups, 8- 12 times in each group. Don't use too much weight, because if you use too much weight in the process of putting down the dumbbell, you can't keep the correct posture. 3, barbell bending: the body is upright, the middle grip distance (shoulder width) holds the barbell and hangs in front of the body. Keep your upper arms close to your sides. Bend upward until the biceps brachii is completely tightened, and then pause. Then slowly recover, don't shake your body back and forth and don't use inertia force when practicing. Even if you are interested in borrowing money, you can't borrow too much. When the load is heavy, the arm is not completely straightened to the lowest point to prevent elbow joint injury.

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