An over the top golf swing occurs as you begin your downswing. Looking from the side, an over the top golf swing sees the club head moving over the top of your hands and towards the target line during your downswing.
This movement continues and the club head moves to the far side of the target line. To now hit the golf ball you have to pull the club head towards the ball and as a result, the club head moves across the target line to the inside or the side that you are standing on. This action of swinging the club head from the far side of the target line to the inside of the target line makes it very difficult to hit straight shots at the target, as to achieve this, the club head needs to move along the target line, rather than across it.
An over the top golf swing is caused when the upper body begins the downswing rather than the lower body. As the upper body rotates to the left and the shoulders turn to the left, the club head moves over the top of your hands. To correct this movement and prevent the over the top swing, you need to sequence the movement of your body correctly on your downswing. The correct movement for your downswing is to rotate from the ground upwards. Initiate your downswing with your knees and hips turning left towards the target. The movement then moves up into your torso as your hips keep rotating left and finally into your upper body and shoulders.
To correct this movement, try the following drill. Place a range basket to the right of the golf ball by about one inch and place it on the outside of the target line. If you are not sure where this is, place an alignment pole or club on the floor so that it is pointing towards the target from where you are going to strike the golf ball. The basket needs to go on the far side of this alignment pole by about three to four inches and one inch to the right of the golf ball. The club head should be able to swing along the target line without hitting the basket, but only just, so make sure you do not have too big a gap between the club head and the basket.
Make some golf swings and work on starting your downswing with your hips rotating left and towards the target. As you do this, keep the club head on the inside of the basket. If you hit the basket, you made an over the top movement, so try again working on keeping the club head on the inside of the basket. Do this slowly at first to get the movement correct and then gradually build the speed of your swing up as you become more confident and proficient with the movement. Once you feel you can swing successfully without the club head striking the basket, place the ball on to the target line and make the same movement. Slow the movement down initially so that you move correctly and keep the club head on the inside of the basket, then strike the golf ball. Keep working on this and gradually build up to a fuller swing speed, maintaining the correct movement of the club head striking the golf ball from inside the basket.
Work on this drill and you will correct your over the top golf swing and start swinging the golf club correctly and along the target line.
If you keep the face of the club aiming down the target line as you do this, you will begin to hit straight shots that improve your accuracy when out on the golf course.