The Effect of Acute Lumbopelvic Muscular Fatigue on Neuromechanical Contraction Characteristics and Nociception

Background: Previous research has examined the acute effects of high-intensity exercise on muscle contractility, revealing potential interference in reaching peak contraction. This study aims to evaluate the impact of a standardized kettlebell swing protocol on low back musculature contractility, measured by tensiomyography (TMG), and pain sensitivity, measured by pressure algometry. Methods: Forty participants were randomly assigned to one of three groups: control, kettlebell swing, and kettlebell isometric hold. Pre-intervention TMG and pressure pain threshold (PPT) measurements were taken, followed by the intervention and post-intervention measurements. Results: Participants averaged 23.85 years (SD ± 2.73), 162.39 lbs (SD ± 28.69), and 174.29 cm (SD ± 12.45). Baseline ANOVAs showed no significant differences between groups for pre-intervention DM or PPT measurements, nor for demographics (p > 0.05). Although no significant within-group differences in TMG measurements were observed, the kettlebell swing group showed small mean differences in muscle displacement and contraction time for the gluteus maximus with effect sizes ranging from 0.09 to 0.49. Conclusions: The study suggests posterior chain muscles, such as the gluteus maximus, are involved in kettlebell swings. Also, despite the lack of significant TMG differences within groups, the kettlebell swing group exhibited small changes in muscle characteristics, enhancing the understanding of exercise-induced hypoalgesia and posterior chain involvement in resistance exercises.