O Electromyographic activation during motor irradiation of proprioceptive neuromuscular facilitation: a scoping review

Résumé

Background: This scoping review examined the effectiveness of motor irradiation in activating specific muscles in adults, using surface electromyography (EMG). The literature suggests motor irradiation, a basic procedure of Proprioceptive Neuromuscular Facilitation (PNF), can stimulate contractions in weak muscles by applying resistance to stronger ones. This could potentially reduce complications in neurological and orthopedic conditions. However, despite its widespread use in physiotherapy, there’s a lack of research on the exact impact of motor irradiation on target muscle activity. Methods: Online databases (PubMed, Scielo, Lilacs, and Google Scholar) were used to identify papers published between 1981-2025, that utilized EMG analysis as a primary or secondary outcome variable in individual of both sexes with and without any disorders. Results: The search yielded 30 potentially relevant articles after removing duplicates. Of these, only nine articles met the inclusion criteria (articles in English, Spanish, or Portuguese that analyzed EMG during PNF motor irradiation). The studies analyzed EMG activity of the upper limb, trunk, and lower limb muscles during motor irradiation (flexor and extensor patterns of both upper and lower limbs). Significant differences were observed between flexor and extensor movement patterns, with specific muscles showing distinct activation profiles. The lower limb patterns evoked higher activation in homologous and contralateral muscles, while upper limb patterns seem to evoke less activation. The limited number of studies, small sample sizes, methodological issues, and the fact that a few studies have investigated upper limb muscle activity highlight the need for further research to achieve a comprehensive understanding of PNF dynamics.