Second, the starting strength, on a solid basis, continue to exercise the muscle groups that provide the starting strength.
Is the angle between calf and thigh greater than or equal to 90? . This can better form a supporting structure and reduce the loss of the knee. Similarly, you can't cross your toes with your knees forward. Spread your legs as far as possible to both sides, tighten your hips and close your bones, so that you can sit on your hips, your hips will not pout, and your upper body can stand upright. It can also reduce the pressure on the lumbar spine, form a cross force when the feet are pulled, and stabilize the center of gravity.
If you want to increase the difficulty, you can start with the distance between your legs, the height of your center of gravity and the load. It is recommended to do what you can when stepping on a horse. Don't pursue difficulty too much.