This prospective, single-blind, randomized controlled trial investigates whether the addition of spinal mobilization to a structured home exercise program improves pain, flexibility, lower-extremity strength, dynamic balance, and jump performance in recreational tennis players (aged 18-45 years; BMI 18-30 kg/m²) with non-radiating mechanical low back pain. Participants were allocated to two parallel groups: a Control Group performing a 21-session home exercise program for 3 weeks, and an Experimental Group performing the same program plus four physiotherapist-administered spinal mobilization sessions (one at baseline and one weekly for 3 weeks). Outcomes were the Visual Analog Scale (VAS) for pain during physical activity, at rest, and at night; the Y-Balance Test; the Vertical Jump Test; the Sit-and-Reach Test; and isometric strength measured with a back-chest-leg dynamometer.