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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 x 890 nm LEDs attached to flexible pads (3×7.5 cm). Each diode spot size was 0.2 cm(2), and each LED power was 12 mW with a power density of 60 mW/cm(2). The arrays were placed in direct contact with the skin for 30 min 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.

Acute systemic thermal therapy can improve arterial stiffness in both animals and humans. We examined and compared the effects of acute local thermal therapy (footbath) on an indicator of human arterial stiffness, cardio-ankle vascular index (CAVI), in 16 healthy young (29.4 ± 0.4 years) and 16 older (59.8 ± 1.7 years) women. Measurements were made at baseline (BL) and at 0 and 30 min after footbath in footbath trial, and at corresponding time points without footbath in control trial. In the footbath trial, subjects immersed their lower legs and feet in water for 30 min, with water temperature ranging from 41 to 43°C. The results showed that footbath elicited significant reductions in CAVI at 0 min compared to the same trial's baseline in both young and older groups (0.55 ± 0.07, P = 0.01 for young; 0.42 ± 0.15, P = 0.03 for older, respectively) with no changes found in the control trials. The percentage of CAVI change at 0 min was significantly greater in young women (91.9 ± 1.1%) compared to older women (96.5 ± 1.8%, P < 0.05). This study indicated that acute warm footbath results in transient improvement of systemic arterial stiffness in both healthy young and older women. Despite similar intervention, the percentage response of arterial stiffness to footbath was attenuated in older women.

The determinants of arterial properties in Chinese migrants to Australia were evaluated. Fifty-eight migrants had recently arrived while 25 were long term residents. All were apparently free of cardiovascular disease. In addition to ultrasound determination of the stiffness of the thoracic aorta, measurements were also made of pulse wave velocities in the trunk and limbs. Factors investigated as potential determinants of arterial properties included age, sex, blood pressure, plasma lipids, urinary electrolyte excretion and duration of residence in Australia. Aortic PWV (PWVAF), PWV from the femoral to dorsalis pedis artery (PWVFD) and the aortic elastic modulus Ep were all dependent on age and mean arterial pressure. Ep was additionally dependent on sodium excretion (negatively), PWVAF on LDL cholesterol (negatively) and migrant status and PWVFD on sex and potassium excretion (negatively). PWV in the arm (PWVBR) was only dependent on sex. Regional aortic stiffness Ep and PWVAF were significantly higher in the established compared with the recent migrants. Dietary differences were evident between the two migration groups, with recent migrants eating significantly more rice meals, but there were no differences in plasma total or HDL cholesterol or triglyceride concentrations. Determinants of the stiffness of the arterial circulation in disease free Chinese subjects change considerably from proximal to distal sites, with age, blood pressure and cholesterol effects being most pronounced proximally and sex and urinary potassium excretion distally. Increasing duration of Australian residence appears to be accompanied by an increase in proximal arterial stiffness.