Immediate effects of monochromatic infrared energy on microcirculation in healthy subjects

Objective: The purpose of this study was to evaluate the influence of monochromatic infrared energy (MIRE) on the microcirculation of the skin surface of the feet in healthy subjects. Background data: Near-infrared energy was shown to increase microcirculation in an animal study. In humans, only one case study demonstrated that MIRE increases microcirculation in the skin of the lower limbs. Methods: Thirty healthy volunteers were recruited and randomly allocated into three groups to receive either: (1) active MIRE; (2) sham MIRE (placebo group); or (3) warm packs (control group) on the feet. The MIRE device comprised an array of 60 × 890nm LEDs attached to flexible pads (3 × 7.5 cm). Each diode spot size was 0.2 cm 2, and each LED power was 12mW with a power density of 60 mW/cm 2. The arrays were placed in direct contact with the skin for 30min delivering a total fluence of 108 J/cm 2 over an area of 22.5 cm 2. Capillary blood cell velocity (CBV) and superficial skin blood flow (flux) were recorded before and after intervention. Results: Significant differences among the three groups were recorded in both CBV and flux (both p > 0.05). Post-hoc comparisons indicated that a significantly greater increase in both CBV and flux occurred in the active MIRE group than in the placebo group and control group (all p > 0.05). Conclusions: A 30-min MIRE produced a significantly greater increase in the CBV and flux of the feet in the active MIRE group than in the placebo and control groups.