Hip adduction exercises involve moving the thigh inwards across the line of the body. Laying on the side of the leg to be worked means gravity can be used to increase resistance. Ankle weights can also be added.
To strengthen the groin muscles the athlete lies on their side with the leg to be worked on the bottom.
The top leg is bent out of the way as shown.
The athlete lifts the bottom leg as high as is comfortable, keeping the knee straight.