Blood Flow Restriction Pressure and its Impact on Electromyographic Activation

Study Overview: This study aims to assess muscle activation during CrossFit exercises using electromyography (EMG) to measure the electrical activity of muscles. EMG is a diagnostic technique that involves placing electrodes on the skin to record the electrical signals generated during muscle contraction. This method allows us to observe and analyze muscle activation in real time, providing crucial insights into how blood flow restriction (BFR) impacts muscle function during exercise. By using EMG, we will evaluate muscle activation in selected upper and lower limb exercises. This will enable us to determine whether the application of BFR, as per the proposed formula, increases muscle activation, as suggested in the physical training literature. The EMG data collected will allow us to compare muscle activity with and without BFR, contributing to a robust scientific understanding of how this technique could be applied more effectively and safely in both athletic training and physical rehabilitation contexts. The duration of the intervention will be 30 minutes, which will be administered by a physiotherapist. Electromyography (EMG) Protocol: General Preparation: 1.1 Skin Preparation: Prior to electrode placement, the skin will be cleaned, dried, and shaved if necessary, to ensure optimal adhesion and electrical conductivity of the electrodes. 1.2 Electrode Placement: Electrodes will be placed on the muscle belly of each target muscle, following established guidelines for EMG electrode positioning to ensure accuracy and consistency in data collection. The specific placement sites are as follows: Quadriceps (Vastus Medialis and Vastus Lateralis): Electrodes will be positioned on the mid-portion of each muscle. Gluteus Maximus: Electrodes will be placed over the thickest part of the muscle, avoiding the upper adipose layer. Hamstrings: Electrodes will be placed on the mid-posterior thigh. Spinal Erectors: Electrodes will be aligned along the lumbar spine, at the level of L3. Pectoralis Major: Electrodes will be positioned on the mid-clavicular line, approximately 5 cm below the clavicle. Triceps Brachii: Electrodes will be placed in the mid-portion of the muscle. Deltoid (Lateral Head): Electrodes will be placed on the middle third of the deltoid, along the lateral aspect of the shoulder. Triceps (Bench Press): The same placement as described for the triceps in the mid-arm position. 1.3 Calculation of Maximum Voluntary Isometric Contraction (MVIC): Prior to the exercise sessions, participants will perform a series of maximum voluntary isometric contractions for each muscle group to be assessed. This will serve as the reference value for subsequent EMG data normalization. 1.4 Normalization of EMG Data: The EMG signals recorded during the exercise sessions will be normalized as a percentage of the EMG signal obtained during the MVIC test. This allows for meaningful comparisons of muscle activation across different exercises, sessions, and participants, accounting for individual variations in muscle strength. EMG Data Recording: EMG data will be collected in real-time during the execution of exercises using mdurance EMG equipment. Each participant will perform 4 sets of 30-15-15-15 repetitions of each exercise at 20-30% of their one-repetition maximum (1RM), with BFR cuffs that will be used to restrict blood flow. The amount of pressure applied will be 80% of the pressure needed for maximal arterial occlusion (which will be previously determined). There will be a 30" rest between sets (without BFR). Lower Limb Exercises: Squat: EMG data will be recorded from the quadriceps and gluteus maximus. Deadlift: EMG data will be recorded from the hamstrings and spinal erectors. Upper Limb Exercises: Bench Press: EMG data will be recorded from the pectoralis major and triceps brachii. Military Press: EMG data will be recorded from the deltoids and triceps brachii. Additional information: there will be no need to assess adherence to the intervention because it is a very short intervention consisting of one session.