Neuromuscular Electrical Stimulation for Patellar and Achilles Tendon Loading: A Scoping Review With Practical Recommendations

OBJECTIVE: To summarize the effects of neuromuscular electrical stimulation (NMES) interventions for improving strength outcomes after injuries such as tendon ruptures and tendinopathies. DESIGN: Scoping review. LITERATURE SEARCH: A bibliographic database search was performed in PubMed, Web of Science, CINAHL, PEDro, and Cochrane Library databases between June and July 2024. STUDY SELECTION CRITERIA: Data on participant demographics, study characteristics, NMES parameters, tendon-related outcomes, and study quality (PEDro scale) were extracted. DATA SYNTHESIS: We performed a scoping review on NMES parameters and dosages used for treating tendon injuries. RESULTS: Of 973 records, 10 studies (5 randomized controlled trials, 3 crossovers, 2 cohorts) involving 166 participants (82.2% male) were included. Most participants were healthy (60%), while others had patellar tendinopathy (20%), spinal cord injury (10%), or Achilles tendon rupture (10%). NMES parameters were well detailed; however, only 3 studies reported the dosage. Within-session, NMES alone or superimposed (NMES + ) altered tendon loading by increasing force, strain, and stress. NMES also changed tendon mechanical properties in both the short- long-term. In long-term studies, implementing NMES + reduced tendinopathy symptoms and pain during tendon loading activities. One study compared NMES + to heavy slow resistance training, while another compared NMES + to baseline. PEDro scores ranged from 1 to 7. CONCLUSIONS: Studies on NMES for tendon loading were generally well-documented. There is room for improvement in detailed reporting of specific dosage and evoked torque to facilitate the clinical implementation of NMES for tendon rehabilitation.