OBJECTIVE : In adults with long-term HIV infection, low bone density and increased fracture risk have emerged as significant comorbidities. Our aim was to assess the association of exercise, nutrition, and medications with bone quality in adults with long-term HIV infection. METHODS : Forty-three adults with HIV infection were enrolled (median BMI 25.7, range 18.2-35.6 kg/m2; median age 57, range 50-69 years). Participants underwent ultradistal radius and tibia high-resolution peripheral quantitative CT (HR-pQCT). Questionnaires included the revised Community Healthy Activities Model Program for Seniors (CHAMPS), the Mini Nutritional Assessment (MNA) as well as medication assessments. Multivariable linear regression models were used to evaluate the association of exercise, nutritional status, tenofovir disoproxil fumarate (TDF) and protease inhibitor (PI) use with bone density and microstructure, adjusting for demographic risk factors. RESULTS : In regression models, higher nutrition scores were associated with higher tibia cortical thickness (R2 = 0.23; β = 0.03; p = 0.044) and higher radius cortical BMD (R2 = 0.43; β = 8.4; p = 0.026). Higher weekly frequency of all physical activities was significantly associated with higher radius trabecular BMD (R2 = 0.38; β = 0.96; p = 0.050), higher radius trabecular number (R2 = 0.31; β = 0.01; p = 0.026), lower tibia and radius trabecular separation (tibia: R2 = 0.30; β = -0.003; p = 0.038; radius: R2 = 0.35; β = -0.003; p = 0.021), and higher radius bone stiffness (R2 = 0.45; β = 0.38; p = 0.047). Higher frequency of bone loading physical activities was significantly associated with higher tibia trabecular density (R2 = 0.44; β = 4.06; p = 0.036), higher tibia bone stiffness (R2 = 0.46; β = 3.06; p = 0.050), and higher tibia estimated failure load (R2 = 0.46; β = 0.17; p = 0.049). TDF used in combination with a PI was associated with lower radius trabecular BMD (R2 = 0.39; β = -41.2; p = 0.042), lower radius trabecular number (R2 = 0.34; β = -0.44; p = 0.009) and greater radius trabecular separation (R2 = 0.42; β = 0.16; p = 0.002), while TDF use without a PI was not associated with reduced bone quality. CONCLUSIONS : In adults with HIV infection, malnutrition is associated with poor cortical bone quality, while reduced frequency of physical activities and specifically reduced frequency of mechanical loading activities are associated with deficient trabecular bone structure and reduced estimates of bone strength. TDF use in combination with a PI is associated with deleterious effects on trabecular bone structure.