The immediate effect of induced pain in the neuromuscular activity of the quadriceps using HD-sEMG in people with patellofemoral pain

• Grant number: 24/19928-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2025
• End date: April 30, 2026
• Field of knowledge: Health Sciences - Physiotherapy and Occupational Therapy
• Principal Investigator: Isabel de Camargo Neves Sacco
• Grantee: Max Willian Roizman
• Host Institution: Faculdade de Medicina (FM). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Patellofemoral pain (PFP) is one of the most common musculoskeletal dysfunctions, mainly in young, physically active women. The nature of this pain is multifactorial, generally with an insidious origin and its treatment is necessarily multimodal. Despite the high prevalence of PFP and the extensive biomechanical literature involving this field, there is still a lack of consensus about its main etiological factors. However, the investigation of local neuromuscular factors is highlighted due to its relevance and predominance. In light of the possible influence of chronic and acute pain over the neuromuscular activity of the quadriceps in PFP, it is important to analyze both influences in the muscle activity profile in this population. Based on this context, this project aims towards a deeper understanding of the neuromuscular activity of the quadriceps, through the exploration of other electromyographic parameters, still little investigated, migrating from the paradigm of bipolar sEMG to the multichannel, high density sEMG. OBJECTIVE: To investigate parameters of the neuromuscular activity of the lateral and medial (obliques) heads of the quadriceps during low intensity isometric contractions under the effect of acute induced pain and in the original condition in individuals with PFP. The main hypothesis of this study, based on the probable immediate influence of induced pain over the reflex and cortical mechanisms, is the existence of neuromuscular changes in the lateral and medial (obliques) compartments of the quadriceps in people with PFP, more particularly in the force production and control and in the vastii muscle activity complexity and variability. METHODS: 30 young males and females will be equally divided between PFP and control groups. Participants will be initially sorted and evaluated with validated questionnaires and will be required to execute an isometric knee extension in a customized dynamometer so the we can measure the high density electromyographic activity of the lateral and medial (obliques) vastii during a low intensity isometric contraction (10% of MVC) before and immediately after the application of a pain inducing protocol in the PFP group. We will quantify the magnitude (standard deviation) and structure (sample entropy) of force variability, the magnitude and variability of muscle activity and the conduction velocity of muscle fibers of both vastii (estimated in the frequency domain). Groups will be compared through mixed bidirectional ANOVAs with independent group factors and repeated measurements (before and after pain), followed by the Newman-Keuls post hoc test, with a significance level established at 0.05.