Sandbag
A unique type of weightlifting tool in that its weight constantly shifts back and forth from the center of mass, challenging the user to adjust and stabilize the bag’s ever-changing shape as it’s raised and lowered.
Squat
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.