The EMG signal informs on the muscle fatigue process as they can assess muscle fibre recruitment and the conduction velocity of the electric signal via the excitable membranes 29, 30. Since they did not consider the involvement of the agonist muscles in generating the torque, it needs to separately measure the fatigue rate for each muscle using another technique as the slope of median frequency, based on time–frequency domain analysis 27, 28. They have reported that inhibitory KT can reduce or delay muscular fatigue during a fatigue protocol, but this index is based on torque changes at the beginning and end of the fatigue protocol 18, 26.
Nonetheless, limited knowledge is available on this issue 18, 26, and they are not systematically suited to identify muscular exhaustion specifically for the muscle with KT. Consequently, it allows us to examine how facilitatory and inhibitory KT affect muscle activation. On the other hand, if these KT techniques could enhance or reduce muscular activity, they might either delay or accelerate muscle fatigue in the long run 25. Indeed, the effects of KT on muscle activity may differ between normal and fatigue conditions because electromyography (EMG) amplitude and muscular activity increase during the fatigue process 24. Nevertheless, these studies have not addressed the effect of KT on muscular activation when the muscles are fatigued. In contrast, other evidence rejected the ability of KT to influence muscle activity 17, 19, 21, 22, 23. Some studies supported the impact of these techniques on muscle activity 17 and on various factors such as muscle fatigue 18, 19, muscle contraction timing 20 and muscle strength 8. Accordingly, the proposed inhibitory and facilitatory techniques were also suggested as a treatment strategy for different musculoskeletal disorders, such as muscle imbalances 12, patellofemoral pain syndrome 8, shoulder impingement syndrome 13, lateral epicondylitis 14 and ankle instability 15.ĭespite facilitatory and inhibitory KT methods being progressively used in injury prevention and rehabilitation programs among athletes 16 previous experiments reported inconsistent findings of the effects of KT on muscle activity. In contrast, applying KT from origin to insertion can facilitate muscle activity by stimulating the muscle spindle 10, 11. Thus, the application of KT from insertion to origin is postulated to inhibit muscle activity by stretching the Golgi tendon organ. Another claimed property of KT, given its application direction, is the modulation of muscle activity by two inhibitory and facilitatory techniques. In addition, KT has been reported to be helpful in the development of joint mobility 4, 5, resulting in an earlier occurrence of muscle peak torque 6, improved functional performance 7, pain relief 8, and increased blood circulation 9. Kinesiotaping (KT) is commonly used among coaches, clinicians and athletes to preserve soft tissues and joints without functional limitations 1, 2, 3. Future studies should investigate the generalizability of current findings to other populations. These findings suggest that the direction of KT cannot reduce, enhance muscle activity or cause changes in muscle exhaustion.
The results showed neither muscle activation (significance for the main effect of KT VM = 0.82, VL = 0.72, RF = 0.19) nor fatigue rate (significance for the main effect of KT VM = 0.11 VL = 0.71, RF = 0.53) of the superficial knee extensor muscles were affected in all four conditions. Furthermore, median frequency slope during all repetitions was reported as the fatigue rate of muscles during different KT conditions and for the control condition (no-tape). The average muscle activity (Root mean square) during the first three repetitions and the repetitions number of 51–100, respectively, were used to calculate the before and after exhaustion muscle activity. The knee extensor muscle activities were recorded using wireless surface electromyography. The protocol included 100 dynamic maximum concentric knee extensions at 90°/s using an isokinetic dynamometry device. Seventeen collegiate athletes (Ten males, seven females, age: 24.76 ± 3.99 years, height: 1.73 ± 0.10 m, mass: 68.11 ± 8.54 kg) voluntarily participated in four dynamic fatigue protocol sessions in which no-tape (control condition), inhibitory, facilitatory and sham KTs were applied to the Vastus Medialis in each session. This study aimed to investigate how facilitatory and inhibitory KT of the Vastus Medialis affected the activation and the fatigue indices of VM, Vastus Lateralis (VL) and Rectus Femoris (RF) throughout a dynamic fatigue protocol.