Abstract: Högström, GM, Pietilä, T, Nordström, P, and Nordström, A. Body composition and performance: influence of sport and gender among adolescents. J Strength Cond Res 26(7): 1799–1804, 2012—Body composition is well known to be associated with endurance performance among adult skiers; however, the association among adolescent crosscountry and alpine skiers is inadequately explored. The study sample comprised 145 male and female adolescent subjects (aged 15–17 years), including 48 crosscountry skiers, 33 alpine skiers, and 68 control subjects. Body composition (%body fat [BF], %lean mass [LM], bone mineral density [grams per centimeter squared]) was measured with a dual-emission x-ray absorptiometer, and pulse and oxygen uptake was measured at 3 break points during incremental performance tests to determine physical fitness levels. Female crosscountry and alpine skiers were found to have significantly higher %LM (mean difference = 7.7%, p < 0.001) and lower %BF (mean difference = 8.1%, p < 0.001) than did female control subjects. Male crosscountry skiers were found to have lower %BF (mean difference = 3.2%, p < 0.05) and higher %LM (mean difference = 3.3%, p < 0.01) than did male alpine skiers and higher %LM (mean difference = 3.7%, p < 0.05) and %BF (mean difference = 3.2%, p < 0.05) than did controls. This study found strong associations between %LM and the onset of blood lactate accumulation and V[Combining Dot Above]O2max weight adjusted thresholds among both genders of the crosscountry skiing cohort (r = 0.47–0.67, p < 0.05) and the female alpine-skiing cohort (r = 0.77–0.79, p < 0.001 for all). This study suggests that body composition is associated with physical performance amongst adolescents.