Muscle worship 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 more out of shape.  Muscle worship can include participants of both sexes and all sexual orientations.
The amount of forceful domination and pain used 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. Male and female bodybuilders offer muscle worship sessions for a price in order to supplement their low or nonexistent income from bodybuilding competitions. Paid sessions sometimes involve sexual gratification; even 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 many gay men that view bodybuilders as sexual objects, not mentioning the fact that bodybuilding is common in the gay community. Also, a lot of gay websites offer muscle worship sessions with some well known male bodybuilders for a limited time for money.   Some bodybuilders however enjoy the practice and get sexually aroused by it, and therefore engage 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. Muscle worship engenders a specific type of pornography, often produced professionally, but also web cam sessions, an underground erotic literature, and specific Internet discussion fora like the #gaymuscle IRC channel. A (possibly fictional) account of muscle worship by H. A. Carson combines it with infantilism.
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. The British tabloid The Sun listed sthenolagnia second in the Top five freaky fetishes after doraphilia. The Sun describe it as a "condition" where men find "hugely sexually attractive [...] mega-bronzed muscle-bound ladies in those weird bodybuilding competitions", and who also "like to be wrestled, lifted up and even carried around by their big iron-pumping dreamgirls".
- 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
- Highway Amazon (2001) (more detailed synopsis)
- Carson, H. A (2010-08). A Roaring Girl: An Interview with the Thinking Man's Hooker. ISBN 9781449080907.
- 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.
- Burt, Josh (9 May 2007). "Top five freaky fetishes". The Sun (London).