How to fill out a “flat” behind

Older men can get “flat” or weak buttocks from spending too much time sitting, which can weaken gluteal muscles and create tight hip flexors. This weakness can place excess demand on other parts of the body, which can lead to pain in the lower back, hips, and knees and increase risk for lower-body injuries. The best way to strengthen a weak backside is to break up prolonged periods of sitting with regular movement and perform exercises that build up gluteal muscles, such as deadlifts, bridges, and step-ups.