A squat is a strength exercise in which the trainee lowers their hips from a standing position and then stands back up. During the descent of a squat, the hip and knee joints flex while the ankle joint dorsiflexes; conversely the hip and knee joints extend and the ankle joint plantarflexes when standing up. Squats are considered a vital exercise for increasing the strength and size of the lower body muscles as well as developing core strength. The primary agonist muscles used during the squat are the quadriceps femoris, the adductor magnus, and the gluteus maximus. The squat also isometrically uses the erector spinae and the abdominal muscles, among others. The squat is one of the three lifts in the strength sport of powerlifting, together with the deadlift and the bench press. It is also considered a staple exercise in many popular recreational exercise programs.