74). The grades were totalled to create a composite score: the lower the score, the better the knowledge. The scores were dichotomised by the median score to those who demonstrated reasonable knowledge and those whose knowledge was insufficient. In order to enough measure negative affective status, the ULCA Loneliness Scale21 and the Sexual Sensation Seeking Scale22 were used.

Statistical methods Analyses were performed using χ2 or Fisher’s exact tests for associating the categorical variables. Continuous variables were analysed by Student’s t test or by the Mann–Whitney non-parametric test for variables distributed abnormally. Logistic analysis identifying variables predicting high-risk sexual behaviour or excessive anaerobic training included variables with p<0.05 after assessment for collinearity and normal distribution

in backwards fashion. The model generated ORs and 95% CIs. Confounding between IAT, sexual risk and sexual orientation, as well as interaction between sexual orientation and IAT, among high-risk participants were assessed using 2-by-2 tables. Analysis was conducted using the SPSS V.17.0 package for Windows software. The study was approved by the E Wolfson Medical Centre Institutional Review Board (WOMC-0058-09). Results Of approximately 600 men who were approached in five gyms in central Tel Aviv, 379 who were older than 18 years of age and reported more than one act of sexual intercourse in the preceding 6 months completed the questionnaire. Of these 379 men, 182 (48%) were MSM (154 reported sex exclusively with men and 28 engaged in sex with both men

and women), while 197 (52%) were heterosexual. The mean±SD age of all the participants was 31.9±6 (range 18–60) years. MSM versus heterosexual men In comparison with heterosexual men, MSM were more likely to be Israeli-born, have lower BMI, have followed a dietary regimen, and used protein supplement powders or anabolic steroids (table 1). They also reported a greater number of casual sex partners and more commonly used drugs before or during sex. MSM demonstrated a Anacetrapib stronger desire to become muscular (OR for preferring to be muscular than rich 3.0, 95% CI 1.9 to 4.9, p=0.01), and a greater percentage reported performing IAT than heterosexual men. Body shaping and improving self-confidence were the main reasons of MSM for training, while losing weight and improving health were more predominant reasons among heterosexual men. The threat of HIV perceived by MSM was lower than that perceived by heterosexual men, yet MSM considered themselves to be at higher risk of acquiring HIV/STI and had higher sexual desire scores than heterosexual men.