Dumbbells are enough. If you want to exercise arm muscles, you should mainly exercise biceps brachii and triceps brachii. The following are the ways to exercise these two parts: First, biceps brachii 1. Alternate bending: mainly practice biceps brachii and separate biceps brachii. Action: Sit (or stand), hang dumbbells at your sides with your hands, palms facing each other, elbows at your sides. With the elbow joint as the fulcrum, bend upward, at the same time, palm up, forearm rotate outward, lift to the highest point to tighten biceps brachii, pause for a moment, and then control the reduction. Do it in turn. 2. Alternate bending: mainly practice biceps muscle peak. Action: Stand, the upper body naturally bends forward, dumbbells are hung in front of the body, and the upper arm rests on the knee or leg on the same side. The other hand is bent on the same knee or leg to stabilize the body. The arm holding the dumbbell bends upward to the highest point, so that the biceps brachii contracts to the limit, stops for a while, and then slowly recovers. 3. Lateral bending: mainly practice the brachialis and forearm muscles. Action: Sit (or stand), hang dumbbells on the side with both hands, palms facing each other, upper arm close to the side, elbow joint as the fulcrum, bend upward to the highest point, pause for a moment, and then slowly recover. Tip: You can do both arms at the same time or alternately. Second, triceps brachii 1. Neck flexion and extension: mainly practice triceps brachii. Action: Sit (or stand), hold one end of dumbbell behind the neck with both hands, palm forward, upper arm fixed, and bend and stretch with elbow as fulcrum. Tip: You can do both arms at the same time or alternately. 2. Bend over and stretch your arms: mainly practice the upper part of triceps brachii. Action: Bend over, lunge forward and backward with your feet, hold your front legs and knees with one hand to stabilize your body, and raise dumbbells with your upper arms close to your body. The triceps brachii forcibly extends the arm backward and upward until the forearm is parallel to the ground, so that the triceps brachii contracts to the limit, pauses for a while, and then slowly recovers. Moreover, protein should be supplemented after exercise to fully recover the injured muscle fibers.