Prehabilitation with Low-Load Blood Flow Restricted Resistance Exercise Training Attenuates Muscle Inhibition of Quadriceps Femoris Muscle in Polytraumatized Patient: A Case Report

Background: Severe knee trauma and chronic cruciate ligament insufficiency are commonly accompanied by marked quadriceps femoris (QF) atrophy and weakness. High-load strengthening is often poorly tolerated by patients with compromised joint stability; therefore, low-load blood flow restriction resistance training (LL-BFRT) may serve as an effective alternative. Case presentation: A 38-year-old male presented 27 months after motorcycle-related polytrauma with right knee pain, instability, complete anterior and posterior cruciate ligament ruptures, and partial QF denervation after femoral nerve injury. Before surgery, he completed a supervised 5-week LL-BFRT prehabilitation program (13 sessions). Results: Lean thigh circumference increased by 5.9% proximally and 17.7% distally. Voluntary activation increased from 87.2% to 92.5%, and maximal QF EMG median frequency decreased by 7.4%. Knee extensor isometric and concentric (60°/s) peak torque increased by 52.4% and 36.9%, respectively. QF isometric endurance time increased from 48.5 to 61.8 s. Stair-climbing time decreased from 18.9 to 10.6 s, repetitions in the step-down test increased from 10 to 17, and the Y-balance test composite score increased from 77.7% to 99.4%. Conclusions: Substantial physiological and clinical improvements in QF voluntary activation, maximal strength, endurance, and lower limb function were observed following a short-term LL-BFRT program in a patient with multiple ligament injuries. Changes in lean thigh circumference were consistent with possible improvements in muscle size; however, muscle hypertrophy was not directly assessed.