First of all, I don't know whether you exercise in the gym or at home. You said you were worried about the inside of the pectoral muscle. This is not a big problem. The shape of the thoracic groove is mainly driven by the lateral chest and pectoralis major muscle.

The pectoral muscle belongs to the large muscle group. Fitness is generally divided into three pieces to practice.

The exercises of the chest muscles are as follows: Draw the outline of the side chest-side line.

The middle part of the chest-commonly known as pectoralis major.

Measurement of chest circumference-commonly known as pectoral groove, if the pectoral muscles are well trained, there is a certain opening in the lower part between the two chests.

Perfect chest muscle shape: the bigger the better, the more perfect it is to stick to the chest like a sesame seed cake. It is not correct to enlarge the picture blindly.

Recommend some actions for you:

Sleeping dumbbell flying birds: generally practice 6-8 groups, each group practices 8- 12 times. The weight of the first group increases and the last group is exhausted (the weight of each group decreases). Action essentials: the lower back should be arched into a bridge shape, and the abdominal muscles and lower back should be tightened.

The barbell moves obliquely up and down, and the number and times are the same as above.

It is recommended to use push-ups (narrow hands) and cross-pull ropes on the chest to squeeze hard after each exercise, which will stimulate the internal measurement of chest muscles.

I wish you success! If you have any questions, please ask me and try your best to help.