"Gaydar" is the ability to distinguish homosexual and heterosexual people using indirect cues. We investigated the accuracy of gaydar and the nature of "gaydar signals" conveying information about sexual orientation. Homosexual people tend to be more sex atypical than heterosexual people in some behaviors, feelings, and interests. We hypothesized that indicators of sex atypicality might function as gaydar signals. In Study 1, raters judged targets' sexual orientation from pictures, brief videos, and sound recordings. Sexual orientation was assessed with high, though imperfect, accuracy. In Study 2, different raters judged targets' sex atypicality from the same stimuli. Ratings of sexual orientation from Study 1 corresponded highly with targets' self-reports of sex atypicality and with observer ratings of sex atypicality from Study 2. Thus, brief samples of sex-atypical behavior may function as effective gaydar signals.

Study Design Controlled laboratory study; cross-sectional. Background Individuals who have undergone anterior cruciate ligament reconstruction (ACLR) have quadriceps muscle impairments that influence gait mechanics and may contribute to an elevated risk of knee osteoarthritis. Objective To compare running mechanics and quadriceps function between individuals who have undergone ACLR to a control group, and evaluate the association between quadriceps function and running mechanics. Methods Thirty-eight individuals who previously underwent primary unilateral ACLR (mean ± standard deviation time since reconstruction, 48.0±25.0 months) were matched to 38 control participants based on age, sex, and body mass index, and underwent assessments of quadriceps muscle performance and running biomechanics. Quadriceps muscle performance was assessed via isokinetic and isometric knee extension peak torque (PT) and rate of torque development over 2 time frames: 0-100 ms (RTD100) and 0-200 ms (RTD200). Running evaluation included assessment of the knee flexion angle (KFA), knee extension moment (KEM), rate of KEM (RKEM), vertical instantaneous loading rate (VILR), and vertical impact peak (VIP). Results On average, there was a smaller KFA (P=.016) in the involved limb compared to uninvolved limb in the ACLR group. Compared to control group limbs, involved limbs in the ACLR group had lower RTD100 (P=.015), lower PT at 60°•sec (P=.011), lower PT at 180°•sec (P=.017), smaller KFA (P<.001), lower KEM (P=.001), lower RKEM (P=.004), and higher VILR (P=.015). Compared to control group limbs, uninvolved limbs in the ACLR group had lower RTD100 (P=.002), lower PT at 60°•sec (P=.011), and smaller KFA (P=.01). For the involved limbs in the ACLR group, there was a low correlation between isokinetic PT at 180°•sec and RKEM (r=0.38, P=.01), and between RTD100 and RKEM (r=0.26, P=.05). No differences were found in isometric strength for any comparison. Conclusions Individuals who have undergone ACLR have bilateral alterations in running mechanics that are weakly associated with diminished quadriceps muscle performance. J Orthop Sports Phys Ther, Epub 22 Jul 2018. doi:10.2519/jospt.2018.8170.

Purpose Obesity influences gait and muscle function, which may contribute to knee osteoarthritis. This study aimed 1) to compare gait biomechanics and quadriceps function between individuals with and without obesity and 2) to examine the association between quadriceps function and gait biomechanics. Methods Forty-eight individuals with and 48 without obesity participated and were matched on age and sex. Gait biomechanics at standardized and self-selected speeds were used to assess peak vertical ground reaction force (vGRF), vertical loading rate (vLR), internal knee extension moment (KEM), peak knee flexion angle (KFA), knee flexion excursion (KFE), and knee joint stiffness. Quadriceps function was assessed using peak isometric strength (peak torque), early (RTD100) and late (RTD200) rate of torque development (RTD), and vastus lateralis cross-sectional area (CSA) and echo intensity (EI). Results When normalized to fat-free mass, individuals with obesity had lower RTD100 (P = 0.04) and RTD200 (P = 0.02) but higher vastus lateralis CSA (P < 0.01) and EI (P < 0.01) compared with normal weight controls. The group–speed interaction was significant for normalized vGRF (P < 0.01), normalized vLR (P = 0.02), normalized KEM (P = 0.03), and normalized knee joint stiffness (P = 0.02). Post hoc analyses indicate a smaller normalized vGRF and normalized KEM, and lower knee joint stiffness in individuals with obesity compared with normal weight controls at self-selected speed. There were main effects of speed for all kinematic and kinetic variables, and body mass index group for all absolute kinetic variables as well as normalized vGRF (all P < 0.001). A lower vastus lateralis EI (P = 0.04) and greater RTD100 (P < 0.01) were associated with a larger KEM in individuals with obesity. Conclusion Individuals with obesity have quadriceps dysfunction that is weakly associated with KEM during walking. Exercise interventions that improve quadriceps function may improve walking mechanics.

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