In the clean and in the jerk, lack of full extension is one of the biggest problems in beginners.
First Things First:
Full extension is a full lock out of a joint, in this case, the ankles, knees, and hip.
Lack of extension often comes from a desire to sneak under the bar too early – probably due to being scared of the weight in the receiving position. But also probably for a good reason – maybe your catch position is weak, your quads are weak, or you’re just uncomfortable in the receiving position.<...