The “Pain Gate” mechanism is one of the speculated explanations for the benefits of Flossband application on soft tissues or joints to reduce pain. This theory, proposed by Wall and Melzack,23 suggests that pain perception can be modulated by the opening or closing of the nerve gate located in the dorsal horn of the spinal cord. This modulation occurs through the activity of small diameter C-fibers and Aδ-fibers or larger diameter Aβ-fibers. Non-painful stimuli, such as compression, skin rubbing, or temperature changes, may activate Aβ-fibers, which may, in turn, activate inhibitory neurons. In the animal model, these inhibitory neurons may close the gate in the spinal cord, thereby reducing the perception of pain by inhibiting the transmission of pain signals from C-fibers and Aδ-fibers.24 Flossband, as a compression tool, exerts pressure on the skin, which may activate large diameter Aβ-fibers, thereby reducing pain. This activation of Aβ-fibers could be one factor explaining the pain reduction observed after Flossband application. Sympathetic activities closely related to pain perception and their excitability may exacerbate the pain perception.25 However, various mechanoreceptors, like Ruffini and Pacinian corpuscles, are present in the skin or the fascia layers. These mechanoreceptors play a role in inhibiting sympathetic nervous system activity when stimulated.26 The sympathetic nervous system is responsible for the ‘fight or flight’ response, which includes increasing heart rate, constricting blood vessels, regulating muscle relaxation response, and others.27,28 When mechanoreceptors are activated, they can induce a parasympathetic response, promoting relaxation and reducing stress-related physiological responses. Although no study has yet examined the effect of Flossband application on mechanoreceptor activation, it is thought the Flossband compression on the skin may stimulate these mechanoreceptors, leading to the inhibition of sympathetic activity. Additionally, the compression may restrict the blood flow, which may produce analgesic effects through releasing beta-endorphins, and the endorphins may influence the speed of pain signal transmission to the brain, which may lead to improved brain response to the pain.29

It is worth noting that the mechanism of Flossband application for pain management may be associated with Aβ-fiber activation, sympathetic activities, and beta-endorphin release. However, current evidence is insufficient to confirm these associations. Therefore, future research is needed to elucidate the exact mechanisms of Flossband application from these perspectives.

“Fascia Glide”, as the second speculated mechanism, explains the benefits of Flossband application on the soft tissues to release the fascia tension, improve muscle flexibility and reduce pain. The assumption of Flossband wrapping on the soft tissue combined with the exercises produces the cohesion force (downwards) and twist force (lateral to medial or media to lateral). These combined forces form shear force (opposite the wrapping direction) acting on the myofascial. Firstly, the shearing force may help the fascia slide between each layer, decreasing myofascial tightness, which is the main effect of improving muscle flexibility after Flossband application.30 Secondly, Flossband compression on the soft tissue increases the intramuscular pressure and may increase myofascial friction during muscle contraction, improving the deep soft tissue temperature. Previous evidence showed that improving the thermal effects of deep soft tissue decreased the fascia viscoelasticity,31 which may also explain the benefits of the soft tissue extensibility after wrapping Flossband. Thirdly, shearing force may reshape the fascia by changing the HA status. HA with a gel status may cause densification of the fascia, which may relate to fascia layers not moving independently,32 and this fascia glide restriction may affect abnormal proprioception responses, such as pain sensitization.33 However, Flossband application on soft tissue may help improve muscle flexibility and reduce pain by restoring fascia function, remodelling the HA status, and reducing receptor sensitization through fascia glide, as speculated by the “Fascia Glide” theory. It is worth noticing that further high-level evidence is needed to investigate these effects.

“Sponge Effect” is the third speculated mechanism explaining the benefits of applying a Flossband. What is the “Sponge Effect”? In general, the “Sponge Effect” refers to the alteration of fluid flow, such as blood flow, lymph flow, ion flow and extracellular flow, through Flossband compression and release. Specifically, the "Sponge Effect" occurs when the Flossband compresses soft tissues by wrapping from the distal to the proximal limb region, squeezing blood flow toward the heart. Upon releasing the Flossband, fresh blood gradually returns to the compressed area, accelerating blood metabolism.34 The “Sponge Effect” also impacts fascia hydration. Cole35 revealed that fascia extrudes water when compressed, which affects the fascia's water content. During the stretching of soft tissue, fascia hydration decreases, and upon release, the fluid content rehydrates to the initial level or even beyond.36 Flossband compression may temporarily dehydrate the fascia, which rehydrates after the compression is released. This dehydration and rehydration cycle helps maintain fascia health and function. However, Flossband compression may also increase the viscosity of the extracellular matrix through HA aggregation, which can lead to soft tissue stiffness and dysfunction.37 Releasing the Flossband promotes rehydration, reducing stiffness and restoring tissue function. Improved fascia hydration reduces adhesions, enhances fascia gliding, aids in force distribution, and alters receptor responses to pain.8 Furthermore, the “Sponge Effect” suggests that Flossband application may affect lymphatic drainage. Flossband application on the soft tissue induces the compression of the superficial fascia, which may reduce the space of the fascial network, leading to lymph vessel compression.38 Upon releasing the Flossband, lymph flow restores gradually, following the “low-resistance pathway” of connective tissue fibers, accelerating interstitial fluid movement, including water, ions, and small solutes. This process may help reduce tissue inflammation by promoting efficient lymphatic drainage.39 Oedema or inflammation occurs due to fluid accumulation in the body's interstitial spaces. Various factors, including increased vascular permeability, increased vascular pressure, lymphatic return obstruction, and others, can cause this accumulation.40 Flossband application as compression therapy may diminish inflammatory responses by decreasing fluid influx and promoting lymphatic drainage, which may reduce swelling and oedema. Vogrin et al.41 hypothesized that Flossband application diminished inflammatory responses by reducing inflammation influx. Even though the speculated mechanisms of the "Sponge Effect" explain how Flossband wrapping benefits soft tissue by reducing inflammation and oedema, improving fluid dynamics, and enhancing flexibility, further high-level evidence is needed to understand how Flossband application affects inflammation and oedema.

“Soft Tissue Ischemia”, as the fourth of the speculated mechanisms, explains the benefit of Flossband application on the soft tissues to improve muscle contraction. The mechanism of tissue flossing involved with Flossband application may be associated with soft tissue ischemia. Pavlů et al.34 demenstrated that the blood flow significantly decreased after two minutes of wrapping Flossband on the upper arm compared to the other side without Flossband application. Driller et al.42 pointed out that wrapping the Flossband with 178mmHg compression for around two minutes on the soft tissue may cause blood flow restriction or local blood occlusion. Based on the previous evidence, applying around 110mmHg compression on the proximal end of the forearm induced vascular occlusion,43 160mmHg compression on the upper limb moderately restricts moderate blood flow, and 300mmHg compression on the upper limb leads to full blood occlusion.44 Flossband wrapped in soft tissue were proven to produce blood flow restriction with venous occlusion, and temporary soft tissue ischemia may theoretically stimulate various physiological and biochemical responses in the human body, such as recruiting fast fibres, increasing the secretion of growth hormone (GH) and norepinephrine (NE), activating neuronal nitric oxide synthase (nNOS), and increasing protein synthesis,45 which may contribute to enhance the strength. In a word, while the theoretical basis for the benefits of Flossband compression exists, further research is essential to validate these effects and understand the specific hemodynamic and physiological changes associated with its use.

Flossband compression on the blood vessels reduces blood flow, which leads to a reduction in oxygen supply. This supply causes lactate to accumulate in the plasma, resulting in metabolite buildup and the recruitment of slow-twitch fibres.34,46 Meanwhile, the metabolite accumulation may stimulate sympathetic nerve activity through chemoreceptive reflex mediated by intramuscular mechanoreceptors and group III and IV afferent fibres.47 The type of III and IV afferent fibres help the fast-twitched fibres recruitment, which increases muscle contraction capacity. Moreover, some evidence showed that lactate accumulation in the intramuscular environment plays a crucial role in regulating the secretion of GH and NE,48 and increasing the GH and NE may contribute to muscle mass and size.49 Increasing the GH may stimulate the synthesis and secretion of insulin-like growth factor 1 (IGF-1), and IGF-1, as a growth mediator, fastens cell fusion and contributes to muscle hypertrophy.50 Flossband application through compression and release, the restricted blood vessels return to reperfusion and the increased flux of Ca2+;51 On the one hand, Ca2+ release generates the contraction of cross-bridge, and on the other hand, Ca2+ release activates the nNOS. nNOS activation increases the NO release, which further triggers the release of hepatocyte growth factor (HGF) from the muscle extracellular matrix, then HGF co-localized with c-MET receptor on the satellite cells, which helps the cell re-fusion.52 In addition, some evidence reported that blood flow occlusion leads to cell swelling, which may contribute to muscle growth by promoting mTOR signalling.53 Even though the mechanism of blood occlusion inducing the production of the Reactive Oxygen Species (ROS) remains controversial. Some evidence reported that blood flow occlusion increases ROS production, which increases muscle glucose intake.54 Therefore, Flossband application on the soft tissues may produce the subsequent hormone regulation and metabolic responses, which may help explain muscle strength increase after Flossband application.

“Joint Effect” is the fifth of the speculated mechanisms explaining the benefits of applying a Flossband on the peripheral joint, such as decreasing pain, reducing inflammation and improving joint mobility. What is a “Joint Effect”? “Joint Effect” hypothesizes that Flossband compression on the joint produces a cohesion force, alters intra-articular fluid pressure (IAP), and redistributes synovial fluid within the joint cavity. Evidence shows that IAP plays an essential role, and it is closely related to active or passive joint movements, particularly at the end range of joint flexion or extension.55 Rutherford56 demonstrated that the effect of IAP depends on whether active muscles distract or compress the knee joint capsule. Flossband wrapping on the joint provides pressure around the joint combined with active and passive movements, which may increase intra-articular pressure, and help retain the vital lubricating synovial fluid in the joint. This can potentially provide a larger joint space, improving the sliding surface between the muscles and joints.57 Ultrasound evidence suggests that applying external compression around the knee could increase joint space associated with fluid shifting and synovial fluid volume.58 When the synovial fluid returns to the synovial cavity, the joint space may widen, possibly explaining the range of motion after Flossband application. Additionally, evidence indicates that removing large effusions from the joint cavity can temporarily relieve pain,59 which may explain the pain reduction observed after Flossband use. The “Joint Effect” speculation primarily shows that Flossband application around the joint may help return the synovial fluid to the joint cavity, which may increase the joint space, decrease inflammatory responses, and reduce pain. However, it is essential to note that these effects are based on hypothesized mechanisms and initial evidence. Therefore, further research is essential to validate the “Joint Effect” and comprehensively understand the impact of the Flossband application on joint function and pain management.