Estimation of vastus intermedius electromyography: Comparison of three methods and their impact on the knee isometric extension moment predicted by an EMG-Driven model

• Published in: Isokinetics and exercise science 2018-01, Vol.26 (4), p.299-306
• Main Authors: de Oliveira, Viviane B., de Oliveira, Liliam F., Menegaldo, Luciano L.
• Format: Article
• Language: English
• Subjects: Electromyography; Knee
• ISSN: 0959-3020; 1878-5913
• DOI: 10.3233/IES-182167

BACKGROUND: Estimations of deep muscles electromyography (EMG) with surface electrodes can be usually performed only indirectly. OBJECTIVE: To investigate the impact of using different approaches for estimating vastus intermedius EMG on the moment sharing patterns among quadriceps femoris components (QF), obtained with an EMG-Driven model, as well as on the joint total moment estimation accuracy, by comparing the calculated knee moment with isometric dynamometer measurements. METHODS: Extensor knee moment and surface isometric EMGs from the four QF components were collected synchronously with knee moment from an isokinetic dynamometer, with the knee flexed at 80∘ and moment level at 40% of the maximum. Neuromuscular excitations u⁢(t) for each QF were derived from the EMGs. Three different estimates of vastus intermedius excitation uVI⁢(t) were tested: (1) surface electrodes on the exposed portion of vastus intermedius; (2) average between vastus lateralis and vastus medialis; and (3) a regression equation to estimate VI EMG from the other QF components. RESULTS: No statistical differences were found among the relative moments, excitation signals, and estimation accuracy by using the three methods. CONCLUSIONS: The average between vastus lateralis and vastus medialis is the recommended choice for being the simplest one.