This study compared the effects of two myofascial chain training programs - the Superficial Posterior Line (PL) and the Spiral Line (SL) - on joint mobility and myofascial isometric endurance in adolescent male football players. Thirty-eight licensed male players (ages 15-16) were enrolled in a randomized crossover trial consisting of two 6-week training phases (12 weeks total), with follow-up measurements at week 16. Each program was delivered twice weekly in 30-minute sessions alongside regular club training. Joint mobility was assessed using goniometry (shoulder flexion, hip flexion, hip extension, popliteal angle), and myofascial isometric endurance was evaluated using the Bunkie Test across five lines (APL, PPL, PSL, LSL, MSL).