Introduction: Knee joint injuries and operative treatment lead to lower limb unloading, which induces atrophy and reduced performance of the quadriceps femoris (QF) muscle. One of the effective methods for strengthening the QF muscle (also in individuals after an anterior cruciate ligament (ACL) injury) is a low-load exercise in combination with restricted blood flow, also known as ischemic exercise. Purpose: We wanted to evaluate the effectiveness of an individualized program with ischemic exercise on atrophy and inhibition of the QF muscle and on the knee joint function in a patient after an extensive reconstruction of knee structures. Methods: Patient was involved in an 8-week exercise program with ischemic exercise, resistance training, and plyometrics. Measurements and test methods included thigh circumference and skinfold measurements, filling out the knee questionnaires KOOS and Lysholm, performance of functional single leg hop test and Y balance test, measurements of QF muscle contractile properties with tensiomiography (TMG) and isokinetic testing of QF muscle maximal torque at 60°/s and 240°/s angular velocity. Results: After the completed exercise program the lean thigh circumference of the injured lower limb increased by 1.9 cm at the distal part and 1.1 cm at the proximal part. The results of the Y balance test of the injured lower limb increased by 5 cm in anterior, 12 cm in posterolateral, and 5 cm in posteromedial direction. The single leg hop test of the injured lower limb improved by 26 cm. Results of TMG show an improvement of contractile properties of the rectus femoris (RF) muscle and 17 % increase in the RF muscle symmetry between the injured and the healthy lower limb. The maximal torque of the injured lower limb knee extensors improved by 43 % at 60°/s angular velocity and by 44 % at 240°/s. Torques of injured lower limb knee flexors decreased by 19 % at 60°/s and by 7 % at 240°/s. Knee flexor and extensor ratio improved, in favor of the extensors. Discussion and conclusion: The results showed positive effects of ischemic exercise on performance, hypertrophy, and improved activation of the QF muscle. Inequality between lower limbs still remains present where the greatest obstacle for achieving bigger progress was the presence of pain in the upper part of the patella. It would be worthwhile to do more research on different approaches for reducing QF muscle inhibitory activity and incorporate them into the training program.