Abstract
Surface electromyography (EMG) is widely used to evaluate neuromuscular activation; however, its signal quality can be influenced by individual anthropometric factors such as body weight, body mass index (BMI), and subcutaneous fat thickness. Despite evidence linking body composition to EMG amplitude, limited research has explored these relationships in trained athletes, particularly comparing load-bearing lower-limb muscles with non-load-bearing upper-limb muscles. This study investigated the relationship between body weight, BMI, and EMG-derived muscle activation parameters-maximum amplitude, maximum root mean square (RMS), and average amplitude in competitive male footballers. Forty inter-university male footballers (age 23 ± 0.94 years) underwent anthropometric assessment (weight, BMI) followed by maximum voluntary contractions (10 s MVCs) of three muscles: biceps brachii, rectus femoris, and lateral gastrocnemius. EMG signals were recorded using an IWorx EMG system, and Pearson’s correlation analysis was applied (p <0.05). Body weight strongly correlated with BMI (r = 0.743, p = 0.014). Lower-limb muscles showed significant associations with BMI, including rectus femoris RMS amplitude (r = 0.646, p = 0.044) and gastrocnemius average amplitude (r = 0.649, p = 0.042). Upper-limb (biceps brachii) activation demonstrated weak, non-significant correlations. Lower-limb muscles exhibited stronger BMI-related neuromuscular responses than upper limbs, likely due to their load-bearing function. Body weight emerged as a more consistent predictor of muscle activation than BMI, emphasising the need for refined body composition assessments in sports science. These findings support the use of individualised EMG interpretation in athletic training, rehabilitation, and injury prevention.
Keywords: BMI, Footballer, Neuromuscular Activation, Surface Electromyography