The Johns 2002 paper goes into many depths:
"Specifically, ultrasound has been shown to modulate vasoconstriction; lymphocyte adhesion properties of endothelium, mast cell degranulation, phagocytosis by macrophage, production of growth factors by macrophages; calcium fluxes in fibroblasts; angiogenesis; proliferation of T-cells, osteoblasts, fibroblasts, and a number of proteins associated with inflammation and repair (IL-1, IL-2, IL-6, IL-8, interferon-γ, fibroblast growth factor-b, vascular endothelial growth factor, collagen) (Table)1,34,40–42,45–53; and to accelerate thrombolyisis.7–16 In general, most of these researchers used a frequency of 1 MHz or 3 MHz, and the intensities ranged from 0.1 to 1.5 W/cm2. An alternative therapeutic protocol employs a frequency of 45 kHz. An intensity range of 5 to 100 mW/cm2 was shown to increase the production of IL-1, IL-8, vascular endothelial growth factor, fibroblast growth factor-b, and collagen; promote bone healing; and accelerate thrombolysis.5,45,54,55 The long-wave (45-kHz) ultrasound increases penetration depth and, therefore, seems to be more appropriate than traditional high-frequency ultrasound (1 MHz and 3 MHz) for promoting revascularization and bone healing at greater depths."increase in function
"The frequency resonance hypothesis suggests that the energy provided to the enzyme by the ultrasound wave may induce transient conformational shifts in certain enzymatic proteins, altering the enzyme's activity (ie, kinases or phosphatases) and the overall function of the cell (Figure 1). Alternatively, ultrasound's resonating force may result in the dissociation of functional multimolecular complexes (Figure 2) or the release of a sequestered molecule by dislodging an inhibitor molecule from the multimolecular complex (Figure 3). In essence, the mechanism of ultrasound's action in Figures 2 and 3 is the same. " "Hypothetically, frequency resonance may imply that different frequencies (1 MHz, 3 MHz, 45 kHz, and others) establish unique resonant or shearing forces (or both). Moreover, various frequencies may affect combinations of proteins or multimolecular complexes in different ways, lending to the possibility of targeted effects at the cellular and molecular levels."