To date, the underlying mechanisms of KT have not been thoroughly investigated. However, there are several postulated mechanisms. First, KT may increase local blood circulation at the application site. Windisch et al. concluded that KT was better than the A-V Impulse Foot Compression System in improving local blood circulation in the knee over a 7-day application period after total knee arthroplasty (TKA) [
66]. Aguilar-Ferrándiz et al. reported that using KT for one month could improve the venous refill time and venous pump function compared to using placebo taping in females with post-menopausal chronic venous insufficiency [
67]. In contrast, Yang and Lee reported that KT did not increase local blood circulation in the lower back over a 15-min period in a population without disabilities [
68]. Woodward et al. indicated that 30 min of KT use was not superior to no tape for improving blood flow in the skin in a population without disabilities [
69]. These conflicting results may be explained by the differences in application period and population characteristics between these studies. Studies by Windisch et al. and Agular-Ferrándiz et al. had longer KT application periods (7 days and 1 month, respectively), and the study populations had musculoskeletal and circulation impairments (post-TKA and chronic venous insufficiency, respectively). Therefore, KT may still be effective for patients with impairments but not for those without disabilities. For the studies conducted in populations with muscle fatigue, the fatigue statuses were induced by isometric [
11,
15], concentric [
13], eccentric [
12,
14], and reciprocal concentric/eccentric exercises [
39]. It is known that eccentric and isometric exercises can induce muscle damage and soreness [
70]. Therefore, KT may be beneficial to populations with muscle fatigue and chronic musculoskeletal diseases as increased blood circulation facilitates recovery by increasing nutrient and waste exchange. Second, KT may suppress pain via the mechanism proposed by the gate control theory [
71]. KT is able to provide tactile stimulation [
72]. This stimulation may lead to the firing of large-diameter afferent fibres, which close the gate to pain signals transmitted by small-diameter afferent fibres. This stimulation then produces a decrease in muscle soreness and musculoskeletal pain and enhances muscle strength. Some meta-analyses have reported evidence for the pain-relieving effect of KT [
6,
7,
9]. These two postulated mechanisms explain why KT is effective in the populations with muscle fatigue and chronic musculoskeletal diseases, but not in the population without disabilities. Third, KT may increase muscle strength by alternating fascia movements. Tu et al. reported that KT changed the motion of fascia during trunk flexion [
73]. Findley et al. reported that substantial force in the muscle was transmitted to the fascia [
74]. Therefore, KT may facilitate muscle strengthening by transmitting a pulling force to the muscle and fascia, as mentioned by Kuo and Huang [
3]. Fourth, Yeung and Yeung proposed that KT may stimulate skin mechanoreceptors [
4]. If the direction in which KT is pulling matches the direction of the muscle contraction, then KT could enhance the muscle spindle reflex and increase the excitability of the motor units; if the directions of the pulling force and muscle contraction are in opposite directions, then KT can stretch the Golgi tendon organs and reduce the activity of the corresponding motor neuron. Currently, there is insufficient research examining the physiological mechanisms of the facilitatory and inhibitory properties of KT in muscle contractions. More physiological studies are thus warranted.