Introduction and background

Studies suggest that various forms of mechanical stress applied to the skin can enhance blood flow, leading to physiological benefits. For example, scalp massage has been reported to increase local blood flow and may improve hair growth [1]. Vibration is another mechanical force that has gained increasing interest as a noninvasive therapy with applications in neurological rehabilitation, exercise performance, and tissue function [2]. Studies have linked vibration to wound healing, an effect thought to be mediated through improvements in skin blood flow (SBF) [3]. SBF is also relevant to thermoregulation [4], aging skin [5], and autoimmune conditions such as psoriasis [6]. These associations provide clinical motivation for understanding the effects of vibration on SBF, although they do not constitute direct evidence regarding the microcirculatory responses to vibration.

The term vibration therapy (VT) describes the application of mechanical oscillations to the body at a specific frequency and amplitude, either globally through whole-body vibration (WBV) or locally, targeting specific muscles or joints [7]. VT has been described as oscillating or linear in delivery, with linear vibration reported to improve jump height [8,9]. However, not all vibration exposure is therapeutic in intent. Vibration associated with occupational exposure (e.g., a jackhammer) represents a distinct paradigm. Chronic occupational exposure has been linked to adverse vascular outcomes, including reductions in digital blood flow and vibration white finger, contributing to regulatory limits on exposure duration in workplace settings enforced by the Occupational Safety and Health Administration (OSHA). These opposing vascular effects underscore the importance of distinguishing between therapeutic and occupational vibration when interpreting literature, as they differ fundamentally in their intent, exposure characteristics, and expected physiological consequences.

Vibration exerts opposing effects on cutaneous perfusion through two competing mechanisms whose dominance depends on the anatomical site of application. In the lower extremities, mechanical oscillations generate shear stress on vascular endothelial cells, activating endothelial nitric oxide synthase (eNOS) and promoting nitric oxide (NO)-mediated vasodilation [10,11]. Concurrently, myogenic control mechanisms, which reflect the intrinsic tendency of vascular smooth muscle to contract or relax in response to changes in transmural pressure, are engaged and contribute to local vasodilation and increased SBF [12]. In contrast, when vibration is applied to the hands and fingers, it preferentially activates densely distributed mechanoreceptors, such as Pacinian corpuscles, whose engagement is directly correlated with reductions in digital blood flow and is mediated by a centrally driven sympathetic reflex, producing bilateral vasoconstriction in both the exposed and contralateral hands [13]. At the molecular level, acute vibration upregulates α₂C-adrenergic receptor-mediated constriction in cutaneous arteries, a mechanism implicated in vibration-induced vascular disease [14]. Because these pathways produce opposing hemodynamic effects, the anatomical site of vibration application is a critical determinant of the vascular response, a distinction that organizes the findings presented in this review.

Despite increasing interest in vibration-based interventions, the existing literature is characterized by substantial methodological heterogeneity, including variability in vibration frequency, amplitude, duration, anatomical application site, participant population, and methods used to quantify SBF. This heterogeneity limits the ability to draw firm conclusions and precludes meaningful quantitative pooling of results. It is also unclear where the boundary lies between adverse occupational exposure and therapeutic benefit, and no scoping review on this topic has been conducted. These gaps highlight the need for a scoping review to map and characterize the current evidence on the effects of vibration of SBF, including its proposed mechanism of action, modalities, intensities, potential therapeutic effects, and contraindications. The substantial heterogeneity across studies in vibration frequency, amplitude, duration, anatomic site, population, and measurement method makes a comprehensive evidence map, rather than quantitative synthesis, the most appropriate next step.