Muscle worship (also called sthenolagnia) is a social behaviour, usually with a sexual aspect (a form of body worship), in which a participant, the worshiper, touches the muscles of another participant, the dominator, in sexually arousing ways which can include rubbing, massaging, kissing, licking, "lift and carry", and various wrestling holds. The dominator is almost always either a bodybuilder, a fitness competitor, or wrestler—an individual with a large body size and a high degree of visible muscle mass. The worshiper is often, but not always, skinnier, smaller, and less fit. Muscle worship can include participants of both sexes and all sexual orientations.
The amount of forceful domination and pain experienced in muscle worship varies widely, depending on the desires of the participants. Sometimes, the dominator uses his or her size and strength to pin a smaller worshiper, forcing the worshiper to praise the dominator's muscles, while in other cases, the worshiper simply feels and compliments the muscles of a flexing dominator. Both male and female bodybuilders offer muscle worship sessions for a price in order to supplement their low or nonexistent income from bodybuilding competitions. When well-known competitors are involved, they offer fans the chance to meet in person and touch a highly muscular man or woman.
Muscle worship is a widespread practice amongst individuals who find bodybuilders, both male and female, attractive. Several websites offer muscle worship sessions with well known male bodybuilders for a limited time in exchange for money. A greater number of websites offer sessions with female bodybuilders. However, some bodybuilders enjoy the practice and are sexually aroused by it, therefore engaging in it for the sake of the thrill.
The 2001 documentary film Highway Amazon chronicles the life of female bodybuilder Christine Fetzer and shows several of her clients engaging in muscle worship. More recent documentaries covering the practice include the American Beauty segment of an HBO's Real Sports with Bryant Gumbel #160, and Channel Five's 2007 Muscle Worship documentary (part of their Real Lives series), profiling in depth the lives of female bodybuilders Lauren Powers and Gayle Moher. A (possibly fictional) account of muscle worship by H. A. Carson combines it with infantilism. Moreover, there are several female bodybuilders that cater to heterosexual male worshippers: Karla Nelson, Alina Popa, Christa Bauch, and more. Muscle worship is also prevalent among gay men. However, the volume of sites would suggest that it is more prevalent among straight men than it is among gay men. There are also sites devoted to women who enjoy worshipping male bodybuilders.
The entry for wrestling in The Encyclopedia of Unusual Sex Practices lists sthenolagnia ("sexual arousal from displaying strength or muscles") and cratolagnia ("arousal from strength") as paraphilias associated with the practice of wrestling for erotic purpose. There appear to be no studies about these proposed concepts; the 2008 comprehensive monograph of Anil Aggrawal does not go beyond defining the terms, with the same meaning, in a list of over 500 similarly terse definitions encountered in the scientific and lay literature. DH Lawrence's book Women In Love and the subsequent Ken Russell film do however feature the scene where two men wrestle naked; the context of Lawrence's investigation of the sexual mores of the time. Russell had to work on conveying sex and the sensual nature of Lawrence's book.
- Hunks, hotties, and pretty boys, Cambridge Scholars, 2008, ISBN 1-4438-0018-X, pp. 159-164
- Shaun Assael, Steroid Nation, ESPN Books, 2007, ISBN 1-933060-37-9, book excerpt
- American Beauty, HBO Special Real Sports with Bryant Gumbel, #160 aired on July 14th, 2010 official synopsis, a text summary and critique, streaming video: part 1, part 2 (the muscle worship proper coverage starts at 3:30 in the 2nd part)
- Benoit Denizet-Lewis, America Anonymous: Eight Addicts in Search of a Life, Simon and Schuster, 2009, ISBN 0-7432-7782-1, pp. 94-96
- John Edward Campbell, Getting it on online: cyberspace, gay male sexuality, and embodied identity, Routledge, 2004, ISBN 1-56023-432-6, pp. 141-145
- Muscle Worship, Hidden Lives series, Channel Five, 9 Apr. 2007, imdb entry, streaming video
- Love, Brenda (1994). The Encyclopedia of Unusual Sex Practices. Barricade Books, Incorporated. p. 313. ISBN 1-56980-011-1.
- Google scholar search returns only  as of 3 Oct. 2010
- Aggrawal, Anil (2008). Forensic and Medico-Legal Aspects of Sexual Crimes and Unusual Sexual Practices. CRC Press. p. 372 and 380. ISBN 1-4200-4308-0.
- Women in Love (film)