In a paper published in the Archives of Sexual Behavior titled Hormonal changes and couple bonding in consentual sadomasochistic activity, two studies were performed to examine  the hormonal changes in testosterone for 58 sadomasochistic (SM) couples. The couples performed a variety of activities designed to produce either pain or pleasure including bondage, sensory deprivation, verbal and non-verbal communication, and various expressions of caring and affection.  Female participants who were bound, receiving stimulation (spanking), and following orders showed increases in testosterone.