Učinek lokalnega mišičnega utrujanja na največji izometrični navor in živčno-mišično aktivacijo evertorjev stopala : magistrsko delo

Jagarinec, Anika (author), Kacin, Alan (mentor), Brezovar, Tjaž (comentor), Umek, Nejc (reviewer)

Uvod: Zvini gležnja predstavljajo 75–85 % vseh poškodb tega sklepa, pri čemer je večina teh inverzijskih. Utrujenost mišic zmanjša učinkovitost živčno-mišičnega nadzora sklepa, kar poveča tveganje za poškodbe. Namen: Namen raziskave je bil ovrednotiti učinek lokalnega utrujanja evertorjev stopala na navor maksimalne hotene izometrične kontrakcije (MVIC) in živčno-mišično aktivacijo mišice peroneus longus pri zdravih posameznikih. Metode: V raziskavo smo vključili 24 zdravih posameznikov (13 moških in 11 žensk), povprečno starih 25,3 ± 3,2 leta, brez zgodovine poškodb merjenega gležnja. Spremembe v aktivaciji evertorjev stopala pred in po koncentrično-ekscentričnem protokolu utrujanja smo ovrednotili z merjenjem največjega navora, doseženega med MVIC, ter z amplitudo in frekvenco EMG signala mišice peroneus longus. Statistična analiza je vključevala testiranje razlik z uporabo dvosmernega parnega t-testa in parametrične korelacije med številom ponovitev giba med protokolom utrujanja in upadom navora MVIC. Rezultati: Po utrujanju je bilo zaznano statistično značilno zmanjšanje navora MVIC evertorjev stopala za 34,7 % (p < 0,001) in invertorjev za 8,0 % (p = 0,005). Razmerje navora MVIC invertorji/evertorji se je povečalo za 44,3 % (p < 0,001), kar kaže na začasno porušeno medmišično ravnovesje. Statistično značilno se je zmanjšala tudi amplituda EMG signala mišice peroneus longus za 12,8 % (p = 0,040); mediana frekvenca je padla za 40,1 % (p < 0,001), povprečna frekvenca pa za 23,7 % (p < 0,001). Ugotovljena je bila negativna korelacija med številom ponovitev, izvedenih med protokolom utrujanja, in upadom navora MVIC (r = –0,442; p = 0,031). Zaključek: Rezultati kažejo, da lokalno utrujanje mišic pomembno zmanjša jakost in živčno-mišično aktivacijo evertorjev stopala, kar lahko poslabša dinamično stabilnost gležnja v smeri inverzije. Ugotovitve so uporabne za načrtovanje preventivnih in rehabilitacijskih programov za zmanjšanje tveganja za zvin ter kronično nestabilnost gležnja.

• Language: Slovenian
• Keywords: magistrska dela, fizioterapija, gleženj, MVIC, peronealne mišice, EMG, utrujenost, stabilnost, živčno-mišični nadzor
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: ZF - Faculty of Health Sciences
• Place of publishing: Ljubljana
• Publisher: [A. Jagarinec]
• Year: 2025
• Number of pages: 41 str.
• PID: 20.500.12556/RUL-172124
• UDC: 615.8
• COBISS.SI-ID: 247988483
• Publication date in RUL: 06.09.2025

Secondary language

• Language: English
• Title: The effect of local muscle fatigue on maximal isometric torque and neuromuscular activation of foot evertors : master's thesis

Abstract

Introduction: Ankle sprains account for 75–85% of all ankle injuries, with the majority being inversion sprains. Muscle fatigue reduces the efficiency of neuromuscular control, leading to a decreased ability to generate force and a higher risk of injury. Purpose: The aim of this study was to evaluate the effect of local fatigue of the foot evertors on maximal voluntary isometric contraction (MVIC) and neuromuscular activation of the peroneus longus muscle in healthy individuals. Methods: Twenty-four healthy participants (13 men, 11 women; mean age 25.3 ± 3.2 years) without a history of injury to the tested ankle were included. Changes in evertor activation before and after a concentric-eccentric fatigue protocol were assessed by measuring peak torque during MVIC and the amplitude and frequency of the peroneus longus EMG signal. Statistical analysis involved paired t-tests and correlation analysis between the number of repetitions of movement during the fatigue protocol and the decrease in torque during MVIC. Results: After fatigue, there was a statistically significant decrease in torque during MVIC of the foot evertors by 34.7% (p < 0.001) and invertors by 8.0% (p = 0.005). The MVIC torque invertor/evertor ratio increased by 44.3% (p < 0.001), indicating a temporary disruption of intermuscular balance. The amplitude of the peroneus longus EMG signal decreased significantly by 12.8% (p = 0.040), while median frequency dropped by 40.1% (p < 0.001) and mean frequency by 23.7% (p < 0.001). A negative correlation was found between the number of repetitions during the fatigue protocol and the MVIC decrease (r = -0.442; p = 0.031). Conclusion: The results show that local muscle fatigue significantly affects muscle strength of the foot evertors and neuromuscular activation, which may reduce dynamic ankle stability. These findings are relevant for designing preventive and rehabilitation programs to lower the risk of ankle sprains and chronic ankle instability.

• Keywords: master's theses, physiotherapy, ankle, MVIC, peroneal muscles, EMG, fatigue, stability, neuromuscular control