Physical Activity and Repetitive Precision Tasks As Determinants of Biomechanical and Viscoelastic Adaptations of the Flexor Digitorum Superficialis Muscle in Professional Shooters

Background: This study aimed to assess the effects of long-term pistol use on the biomechanical and viscoelastic properties of the flexor digitorum superficialis (FDS) muscle, using myotonometry (MyotonPRO) to compare State Protection Service officers with individuals who do not use pistols. Methods: This cross-sectional study included 50 healthy adult males aged 30-40 years, of whom 25 were professional shooters and 25 were non-pistol users. The biomechanical and viscoelastic properties of the FDS muscle of the dominant hand were assessed using the MyotonPRO device at six contraction levels ranging from 0 to 100% of maximum voluntary contraction (MVC), based on grip strength measured with a digital dynamometer. Results: Professional shooters showed lower muscle tone, stiffness, and decrement values, suggesting greater elasticity; however, these differences were not statistically significant. Viscoelastic parameters, including relaxation time and creep, were generally higher. In unadjusted analyses, creep differed at 80% and 100% MVC (p = 0.039 and p = 0.002) with moderate effect sizes, but these differences were not significant after Benjamini-Hochberg correction. The lowest adjusted value was observed for creep at 100% MVC (q = 0.060), indicating a trend toward significance. Conclusions: Long term pistol use was not associated with increased muscle tone or stiffness of the FDS muscle. Although viscoelastic differences were observed, none remained significant after correction. Consistent patterns, particularly for creep at higher loads, may suggest subtle differences in muscle behavior; however, these findings should be interpreted with caution.