An orgasm occurs following sexual stimulation and involves muscle contractions in the genital area due to the release of certain chemicals (endorphins) in the brain. Blood flow is increased to the genital area during sexual arousal, which is required to provide nutrients and substances for a part of the body to function optimally. Orgasms may become less powerful due to aging, stress, anxiety, low desire, poor arousal, a weak pelvic floor and more.