Spinal cord injuries (SCI) can induce a variety of troubles and disabilities, from muscle atrophy and chronic pain to partial or complete loss of sensory function, organs function, muscle force, and motor control, greatly changing the patient’s quality of life. Neuromuscular electrical stimulation (NMES) is a rehabilitation technique widely used for SCI cases that consists on inducing muscle activation and contraction through the application of a series of electrical stimuli on injured muscles, allowing the improvement of muscle and sensory function, quality of life and even inducing partial or full recover of sensibility, muscle force and movements. Applications usually adopt open-loop systems, for its simplicity and ease of testing. However, recent studies suggest that closed-loop systems are able to compensate problems and ensure more stability, security, precision and high performances. This work presents the development of a linear closed-loop PID controller for NMES applications and investigates the consequences of different patient’s parameter values on the closed-loop response. Results showed that the controller was able to perform appropriately throughout the entire expected range of input values, having a good potential for being used on different patients with different cases, showing greater flexibility, responsiveness and capability of adapting the response to the patient’s needs. Results also indicated that the IMC method for the controller design allowed greater adaptability and precision on the closed-loop responses.