Ghareeb, DM, McLaine, AJ, Wojcik, JR, and Boyd, JM. Effects of two warm-up programs on balance and isokinetic strength in male high school soccer players. J Strength Cond Res 31(2): 372-379, 2017-One of the most common warm-up programs used to prevent injury in soccer, FIFA11+, integrates aerobic, strength, and balance. The purpose of this study was to compare FIFA11+ to a new warm-up program (NWP) on balance and isokinetic strength of the quadriceps and hamstrings at 60, 180, and 300°·s in male high school soccer players. Participants at one school (n = 17) performed the NWP before practice for 6 weeks during one soccer season, whereas participants at another school (n = 17) performed FIFA11+. There were no differences at baseline. At posttest, players in NWP significantly improved (p < 0.01) in Overall Stability Index Balance, Anterior/Posterior Index Balance, and Medial Lateral Index with large effect sizes (ES) > 1.3. No changes were seen in FIFA11+. Isokinetic strength peak torque increased at 60°·s in the quadriceps and hamstrings in dominant and nondominant legs in NWP (p < 0.01, ES, 0.59-1.02) and in hamstrings in FIFA11+ (p ≤ 0.05, ES, 0.32-0.40). At 180°·s, NWP improved peak torque (p < 0.01, ES, 0.74-0.90) except hamstrings in the nondominant leg, whereas FIFA11+ showed improvements across all muscle groups (p < 0.01), but with smaller ES, 0.25-0.84. Both programs improved isokinetic peak torque at 300°·s except hamstrings in the nondominant leg in NWP, although ES were higher in NWP (ES, 0.60-1.03) than FIFA11+ (ES, 0.31-0.42). The NWP seems to be effective for soccer conditioning by improving balance and isokinetic strength.