A single dose of oral nattokinase accelerates skin temperature recovery after cold water immersion: A double-blind, placebo-controlled crossover study

Nattokinase (NK) intake may improve blood flow; however, its effects on skin temperature, which is predominantly controlled by skin surface blood flow, are unknown. The purpose of this study was to determine the effects of a single dose of NK on changes in skin temperature after cold water immersion. A double-blinded, placebo-controlled, crossover intervention study was performed on nine healthy men. The participants were randomised to receive either a single dose of 2,000 fibrinolytic units (FU) of NK or a placebo with subsequent crossover. Two hours after supplementation, the participants immersed both hands in a water bath maintained at 10 °C for 1 min. Skin temperature, perceived coldness, cardiac output, and sympathetic nervous activity were measured before, during, and after water immersion. Two-way analysis of variance showed a significant effect of treatment interaction on the skin temperature of the middle finger, palm, and back of the right hand (p < 0.05). These findings represented that the skin temperatures of the middle finger, palm, and back of the right hand immersed in the cold water were significantly dropped due to the cold water immersion, and then recovered more quickly by NK intake than by placebo intake. The results of the current study highlight the potential implications of NK for the prevention of excessive vasoconstriction. It may be more significant for those with cold-sensitive constitution, such as women and elderly. In contrast, the acute administration of 2,000 FU of NK did not affect changes in heart rate, cardiac output, sympathetic nervous activity compared with a placebo in healthy men

The Effects of 10-Week Strength Training in the Winter on Brown-like Adipose Tissue Vascular Density

There is no evidence of the effect of exercise training on human brown-like adipose tissue vascular density (BAT-d). Here, we report whether whole-body strength training (ST) in a cold environment increased BAT-d. The participants were 18 men aged 20&ndash;31 years. They were randomly assigned to two groups: one that performed ST twice a week at 75% intensity of one-repetition maximum for 10 weeks during winter (EX; n = 9) and a control group that did not perform ST (CT; n = 9). The total hemoglobin concentration in the supraclavicular region determined by time-resolved near-infrared spectroscopy was used as a parameter of BAT-d. ST volume (Tvol) was defined as the mean of the weight &times; repetition &times; sets of seven training movements. The number of occasions where the room temperature was lower than the median (NRcold) was counted as an index of potential cold exposure during ST. There was no significant between-group difference in BAT-d. Multiple regression analysis using body mass index, body fat percentage, NRcold, and Tvol as independent variables revealed that NRcold and Tvol were determined as predictive of changes in BAT-d. An appropriate combination of ST with cold environments could be an effective strategy for modulating BAT

Compression Stockings Suppressed Reduced Muscle Blood Volume and Oxygenation Levels Induced by Persistent Sitting

This study quantitatively analyzed the effects of 3 h of constant sitting on skeletal muscle oxygenation in the lower extremities, using near-infrared time-resolved spectroscopy (NIRTRS). The effects of compression stockings were also evaluated. Eleven healthy men (age, 30.0 &#177; 6.7 years) maintained their knee joints at 90&#176; flexion during 3 h of constant sitting and wore a compression stocking on either the right or left leg. The side the stocking was worn was chosen randomly. Subsequently, leg circumference and extracellular water were measured. After 3 h of sitting, both factors increased significantly in uncompressed limbs. Furthermore, intracellular water and muscle oxygenation had significantly decreased. In contrast, extracellular water had not increased in the limbs wearing compression stockings. Furthermore, the increased circumference of compressed limbs was significantly smaller than that of uncompressed limbs. Decreases in oxygenated hemoglobin and total hemoglobin were significantly smaller in compressed limbs than in uncompressed limbs (oxy-Hb; p = 0.021, total-Hb; p = 0.013). Three hours of sitting resulted in decreased intracellular water and increased extracellular water in the lower extremities, leading to reduced blood volume and oxygenation levels in skeletal muscle. Compression stockings successfully suppressed these negative effects

Correlation of Plasma Amino Acid and Anthropometric Profiles with Brown Adipose Tissue Density in Humans

This study examined the relationship between plasma amino acid (AA) concentrations, including branched-chain AAs, and brown adipose tissue density (BAT-d). One hundred and seventy-three subjects (69 men, 104 women) aged 22–68 years were recruited during the winter season. AAs were comprehensively quantified using liquid chromatography-time-of-flight-mass spectrometry. The total hemoglobin concentration in the supraclavicular region ([total-Hb]sup), an indicator of BAT-d, was assessed using near-infrared time-resolved spectroscopy. Anthropometric parameters, including age, percentage of body fat, and visceral fat, were evaluated. Factors associated with higher (≥74 µM) or lower (&lt;74 µM) [total-Hb]sup were investigated by multiple logistic regression models that included AA concentrations alone (model 1) or AA concentrations and anthropometric parameters (model 2) as independent variables. When adjusted for the false discovery rate, [total-Hb]sup was positively correlated with glycine and asparagine levels in men and with the serine level in both men and women and was negatively correlated with the branched-chain AA concentration in men. Models 1 and 2 correlated with higher or lower BAT-d for men (r = 0.73, p = 0.015) and women (r = 0.58, p = 0.079) and for men (r = 0.82, p = 0.0070) and women (r = 0.70, p = 0.020), respectively. A combination of anthropometric parameters and plasma AA concentrations could be a reliable biomarker for higher and lower BAT-d

Vigorous-Intensity Physical Activities Are Associated with High Brown Adipose Tissue Density in Humans

Brown adipose tissue (BAT) plays a role in adaptive thermogenesis in response to cold environments and dietary intake via sympathetic nervous system (SNS) activation. It is unclear whether physical activity increases BAT density (BAT-d). Two-hundred ninety-eight participants (age: 41.2 &plusmn; 12.1 (mean &plusmn; standard deviation), height: 163.6 &plusmn; 8.3 cm, weight: 60.2 &plusmn; 11.0 kg, body mass index (BMI): 22.4 &plusmn; 3.0 kg/m2, body fat percentage: 25.4 &plusmn; 7.5%) without smoking habits were categorized based on their physical activity levels (a group performing physical activities including walking and moderate physical activity (WM) and a group performing WM + vigorous-intensity physical activities (VWM)). We measured the total hemoglobin concentration ([Total-Hb]) in the supraclavicular region, an index of BAT-d, and anthropometric parameters. [Total-Hb] was significantly higher in VWM than WM for all participant groups presumably owing to SNS activation during vigorous-intensity physical activities, and unrelated to the amount of total physical activity levels. Furthermore, multiple regression analysis revealed that BAT-d was related to visceral fat area and VWM in men and related to body fat percentage in women. We conclude that vigorous-intensity physical activities are associated with high BAT-d in humans, especially in men

Applicability of Supraclavicular Oxygenated and Total Hemoglobin Evaluated by Near-Infrared Time-Resolved Spectroscopy as Indicators of Brown Adipose Tissue Density in Humans

Brown adipose tissue (BAT) may potentially be used in strategies for preventing lifestyle-related diseases. We examine evidence that near-infrared time-resolved spectroscopy (NIRTRS) is capable of estimating human BAT density (BAT-d). The parameters examined in this study are total hemoglobin [total-Hb]sup, oxygenated Hb [oxy-Hb]sup, deoxygenated Hb [deoxy-Hb]sup, Hb O2 saturation (StO2sup), and the reduced scattering coefficient in the supraclavicular region (&mu;s&rsquo;sup), where BAT deposits can be located; corresponding parameters in the control deltoid region are obtained as controls. Among the NIRTRS parameters, [total-Hb]sup and [oxy-Hb]sup show region-specific increases in winter, compared to summer. Further, [total-Hb]sup and [oxy-Hb]sup are correlated with cold-induced thermogenesis in the supraclavicular region. We conclude that NIRTRS-determined [total-Hb]sup and [oxy-Hb]sup are useful parameters for evaluating BAT-d in a simple, rapid, non-invasive manner