Because of playing badminton for a long time, it is not uncommon that one side of both arms is not thick, and the muscles of the right arm are much larger than those of the left arm. In order to adjust the muscle balance of the left arm and right arm, the following measures can be taken:

1. Change exercise habits: When playing badminton, try to serve with your left hand, catch the ball with your left hand, and pick it up with your left hand. Let your left hand take part in more sports and promote the development of your left arm muscles.

2. Intensive training: Strengthen the left arm muscles, such as using dumbbells to bend the arm, bending and stretching the back arm of the dumbbell neck, lifting the dumbbell sideways, or using elastic belt for training. 15- 20 times per group, 4-6 groups per day.

3. Massage: Promote muscle recovery and growth through massage. Massage along the veins and lymph nodes of the arm for 3 minutes at a time.

4. Stretching: Proper stretching before and after exercise helps to relax muscles and promote blood circulation.

5. Diet: Ensure adequate nutrient intake, especially protein and carbohydrates, to support muscle growth and recovery.

It should be noted that it takes time and patience to adjust the muscle balance of the left and right arms. So you need to insist on training and massage, change your exercise habits and strengthen the training of your left arm.