what causes a body to get stiff
A Garrett Shepherd , NASM Elite Trainer , Fitness, answered. Sitting can make you stiff! Surprisingly, something as relaxing as sitting can make you very stiff. This is usually caused by the shortening of the hip flexors while you are in a sitting position for an extended period of time. Keep your hip flexors loose and if you have been sitting for a while, stretch your hip flexors when you get up.