Most people are much stronger above the knee than below on deadlifts. However, if you feel that the disparity is too great, there are a few potential problems you may want to check:
- Starting position with the hips too high.
- Poor mobility causing low back rounding just to grab the bar
- Losing body tightness due to poor breath control.
- Simply just being weak off the floor.
If your hips are too high, you are pulling from the most mechanically inefficient position. Additionally, it is putting a lot of strain on your back that can potentially be dangerous to your lumbar region.
The best thing to do is get some video of yourself to see what you look like. Take it from a couple different angles: 3/4 view on the front, and a side view. The 3/4 view is from the front but at an angle that also lets you see your leg and back position. A good example, as well as some professional deadlift critiquing would be in this video from Brandon Lilly:
If you don’t have mobility or body position issues, there are some exercises that can really help:
Use 50% of your heaviest deadlift for the day and do 2-3 sets of 10-15 reps. Aim for more volume, but if you can barely make the minimums it’s OK. Your glutes and traps may be particularly challenged at first.
Speed Deadlifts help reinforce technique, and pulling with the intent to break the bar off the floor as fast as possible. Essentially use 55-65% of your training max, and do 10-15 singles on a 30s clock. In other words, every 30 seconds get into position breath in and pull.
Both of the above are assistance exercises I’ve used and have produced some good results. They shouldn’t replace actually training the deadlift off the floor. Make sure you pull the bar toward you throughout the movement, activating your lats.