The mTrigger® Biofeedback System uses surface electromyography (sEMG) instrumentation to measure the electrical activity produced by targeted muscle groups during therapeutic exercise. Decreased EMG activity and neuromuscular control inhibit patients’ ability to regain pre-injury functionality. The primary rationale for the use of biofeedback in physical therapy is that monitoring voluntary muscle activation improves accuracy and quality of performance and helps patients make faster progress. When patients begin to use their own electrical system early on through volitional contraction, they gain both motor control and strength, as well as re-educate the neuromuscular pathway. By communicating muscle activity in real time, biofeedback enables the reacquisition of pre-injury performance.
However it presents clinically, most people in physical therapy for musculoskeletal or orthopedic concerns are there due to inhibition. Inhibition is a lack of volitional contraction caused by post-injury or post-surgery effusion, pain, swelling, etc. As a result of inhibition, atrophy can occur, which has numerous negative effects, including weakness, asymmetry, avoidance patterns, and increased re-injury risk. Combating inhibition and atrophy is critical to making the strength and neuromuscular control gains that get patients back to functionality. Compensation (activity in a co-contracting muscle that is not the target muscle but can assist in the performance of particular exercises) and inability to control resting tone/tension also impacts rehabilitation goals.
Reversing inhibition via voluntary contraction helps to “wake up” the neuromuscular pathway and attack neuromuscular deficits that follow surgery or injury head-on.
The concept known as order of recruitment is based on Heinemann’s Size Principle, which states that under load, motor units are naturally recruited from smallest to largest. In practice, this means that Type I muscle fibers (slow-twitch, low-force, fatigue-resistant, small diameter) are naturally activated before Type II muscle fibers (fast-twitch, high-force, less fatigue-resistant, excitable, large diameter). Since muscle atrophy predominantly affects Type I fibers (Mechanisms for fiber-type specificity of skeletal muscle atrophy; Muscle type and fiber type specificity in muscle wasting), recruitment thereof is critical to reverse the effects of muscle inhibition and atrophy. When using EMS (electronic muscle stimulation), all nerve fibers are stimulated simultaneously. This does not allow for the natural order of motor unit recruitment to take place, and thereby misses the opportunity to rebuild the neuromuscular pathway in a manner reflective of activity in a healthy muscle. Alternatively, a biofeedback interface like that in the mTrigger system provides real-time audiovisual feedback of a patient’s volitional contraction, encouraging maximum volitional contraction (MVC) and allowing for a temporal and spatial understanding of activation. Biofeedback thus improves accuracy and muscle learning with every rep. By contracting strongly and accurately, re-education of the entire neuromuscular pathway is achieved, and patients and therapists have a better understanding of neuromuscular control. Biofeedback can also be used to address relaxation or intentional inhibition training when there are muscles that are being activated too much during certain exercises. The basic tenets of order of recruitment support the use of biofeedback to facilitate the performance of volitional contractions and improve the efficacy of therapeutic exercise.
Solution in Action
When using the mTrigger Biofeedback System, the clinician sets the MVC goal for the inhibited muscle so that a strong voluntary effort is required by the patient for each contraction. An amplifier sends the measured EMG activity via Bluetooth to a mobile device (iOS or Android) with the mTrigger mobile application installed. This signal is displayed visually in the app interface so that patients understand and actively engage in their exercises in real time. The interface provides interactive biofeedback activities where patients can train, play games, and track their performance, while real-time visualization helps them learn what true neuromuscular activation feels like. Ultimately, the data provided by mTrigger motivates patients to engage in their rehabilitation and achieve better health outcomes by way of regained neuromuscular control and functionality.
The mTrigger Biofeedback System offers incredible versatility. With lower extremity, upper extremity, trunk, pelvic, and hand applications, any muscle group accessible via sEMG is accessible with mTrigger. Suitable for isometric, dynamic, and functional exercises alike, the mTrigger Biofeedback System has applications from pre- and post-op assessment to return to play. Get back to play, back to life with the mTrigger Biofeedback System.