If youre using heavy weights you can use your thighs to push the dumbbells back as you roll back on the flat bench.
Dont let the dumbbells touch at the top of each rep.
Keep the rep timing slow, lowering the dumbbells at a slower pace than raising them.
Use a full range of motion - lower the dumbbells all the way down!
Instructions
The reverse grip is the same as the dumbbell bench press except you use a reverse grip. Set up for the exercise by grasping a set of dumbbells and sitting on the end of a flat bench with the ends of the dumbbells resting on your knees.
Slowly lay back on the bench and push the dumbbells straight up above your chest.
Twist the dumbbells so that your palms are facing your shoulders. This is the starting position for the exercise.
Slowly lower the dumbbells down keeping your palms in line with your middle chest.
When the handles get to around chest height, pause and raise the dumbbells back to the starting position.