Comparison of energy expenditure and substrate oxidation between walking and running in men and women.

PURPOSE: The present study compared energy metabolism between walking and running at equivalent speeds during two incremental exercise tests. METHODS: Thirty four university students (18 males, 16 females) were recruited. Each participant completed two trials, consisting of walking (Walk) and running (Run) trials on different days, with 2-3 days apart. Exercise on a treadmill was started from initial stage of 3 min (3.0 k/m in Walk trial, 5.0 km/h in Run trial), and the speed for walking and running was progressively every minute by 0.5 km/h. The changes in metabolic variables, heart rate (HR), and rating of perceived exertion (RPE) during exercise were compared between the trials. RESULTS: Energy expenditure (EE) increased with speed in each trial. However, the Walk trial had a significantly higher EE than the Run trial at speeds exceeding 92 ± 2 % of the maximal walking speed (MWS, p < 0.01). Similarly, carbohydrate (CHO) oxidation was significantly higher in the Walk trial than in the Run trial at above 92 ± 2 %MWS in males (p < 0.001) and above 93 ± 1 %MWS in females (p < 0.05). CONCLUSION: These findings suggest that EE and CHO oxidation during walking increase non-linearly with speed, and walking at a fast speed causes greater metabolic responses than running at the equivalent speed in young participants.

Ground reaction force and electromyograms of lower limb muscles during fast walking.

Background: Physically active status is an important contributor to individual health. Walking is regarded as commonly accepted exercise for exercise promotion. Particularly, interval fast walking (FW), consisting of alternating between fast and slow walking speeds, has gained popularity from practical viewpoints. Although previous studies have determined the short- and long-term effects of FW programs on endurance capacity and cardiovascular variables, factors affecting these outcomes have not been clarified. In addition to physiological variables, understanding of mechanical variables and muscle activity during FW would be a help to understand characteristics of FW. In the present study, we compared the ground reaction force (GRF) and lower limb muscle activity between fast walking (FW) and running at equivalent speeds. Method: Eight healthy men performed slow walking (45% of the maximum walking speed; SW, 3.9 ± 0.2 km/h), FW (85% of the maximum walking speed, 7.4 ± 0.4 km/h), and running at equivalent speeds (Run) for 4 min each. GRF and average muscle activity (aEMG) were evaluated during the contact, braking, and propulsive phases. Muscle activities were determined for seven lower limb muscles: gluteus maximus (GM), biceps femoris (BF), rectus femoris (RF), vastus lateralis (VL), gastrocnemius medialis (MG), soleus (SOL), and tibialis anterior (TA). Results: The anteroposterior GRF was greater in FW than in Run during the propulsive phase (p < 0.001), whereas the impact load (peak and average vertical GRF) was lower in FW than in Run (p < 0.001). In the braking phase, lower leg muscle aEMGs were higher during Run than during SW and FW (p < 0.001). However, in the propulsive phase, soleus muscle activity was greater during FW than during Run (p < 0.001). aEMG of tibialis anterior was higher during FW than during SW and Run in the contact phase (p < 0.001). No significant difference between FW and Run was observed for HR and RPE. Conclusion: These results suggest that the average muscle activities of lower limbs (e.g., gluteus maximus, rectus femoris, and soleus) during the contact phase were comparable between FW and running, however, the activity patterns of lower limb muscles differed between FW and running, even at equivalent speeds. During running, muscles were mainly activated in the braking phase related to impact. In contrast, during FW, soleus muscle activity during the propulsive phase was increased. Although cardiopulmonary response was not different between FW and running, exercise using FW might be useful for health promotion among individuals who cannot exercise at high-intensity.

Navicular drop is negatively associated with flexor hallucis brevis thickness in community-dwelling older adults.

BACKGROUND: Flatfoot is characterized as a lower longitudinal arch and is a common foot deformity in older adults. Foot intrinsic muscle dysfunction has been considered as one of the factors for a lower medial longitudinal arch. The objective of this study was to investigate the association of the navicular drop with the thickness of foot intrinsic muscles in older adults. RESEARCH QUESTION: Which intrinsic muscle contributes most to support the medial longitudinal arch in older adults? METHODS: We studied 88 community-dwelling older adults (mean age 74.2 ± 6.2 years). We measured the navicular height, the calcaneus inclination, and hallux valgus angle on the right foot in the sitting and standing positions using a 3D foot scanner. Then, we calculated the navicular drop and changes in the calcaneus inclination from the sitting to the standing position. The muscle thickness of the flexor hallucis brevis (FHB), flexor digitorum brevis (FDB), and abductor hallucis (AbH) was measured on the right foot using Bmode ultrasonography. RESULTS: Multiple regression analysis demonstrated that FHB thickness was significantly associated with navicular height in the standing positions (ß = 8.568, P = 0.016) as well as navicular drop (ß = -9.495, P = 0.037) after adjusting for age, sex, height, weight, and hallux valgus angle. There was no association with FDB or AbH. The thickness of any intrinsic muscle was not associated with the calcaneus inclination or changes in the calcaneus inclination. SIGNIFICANCE: Our data suggest that FHB plays an important role in preventing navicular drop and that intrinsic muscles likely do not contribute to the rearfoot angle in older adults.

Preferential oxidation of carbon monoxide catalyzed by platinum nanoparticles in mesoporous silica.

Preferential oxidation (PROX) of CO is an important practical process to purify H2 for use in polymer electrolyte fuel cells. Although many supported noble metal catalysts have been reported so far, their catalytic performances remain insufficient for operation at low temperature. We found that Pt nanoparticles in mesoporous silica give unprecedented activity, selectivity, and durability in the PROX reaction below 353 K. We also studied the promotional effect of mesoporous silica in the Pt-catalyzed PROX reaction by infrared spectroscopy using the isotopic tracer technique. Gas-phase O2 is not directly used for CO oxidation, but the oxygen of mesoporous silica is incorporated into CO2. These results suggest that CO oxidation is promoted by the attack of the surface OH groups to CO on Pt without forming water.

Direct PEM fuel cell using "organic chemical hydrides" with zero-CO2 emission and low-crossover.

A series of "organic chemical hydrides" such as cyclohexane, methylcyclohexane, cyclohexene, 2-propanol, and cyclohexanol were applied to the direct PEM fuel cell. High performances of the PEM fuel cell were achieved by using cyclohexane (OCV = 920 mV, PD(max) = 15 mW cm(-2)) and 2-propanol (OCV = 790 mV, PD(max) = 78 mW cm(-2)) as fuels without CO(2) emissions. The rates of fuel crossover for cyclohexane, 2-propanol, and methanol were estimated, and the rates of fuel permeation of cyclohexane and 2-propanol were lower than that of methanol. Water electrolysis and electro-reductive hydrogenation of acetone mediated by PEM were carried out and formation of 2-propanol in cathode side was observed. This system is the first example of a "rechargeable" direct fuel cell.

Heat transfer and thermographic analysis of catalyst surface during multiphase phenomena under spray-pulsed conditions for dehydrogenation of cyclohexane over Pt catalysts.

Dehydrogenation of cyclohexane over Pt/alumite and Pt/activated carbon catalysts has been carried out for hydrogen storage and supply to fuel cell applications. An unsteady state has been created using spray pulsed injection of cyclohexane over the catalyst surface to facilitate the endothermic reaction to occur efficiently. Higher temperature of the catalyst surface is more favorable for the reaction, thus the heat transfer phenomena and temperature profile under alternate wet and dry conditions created using spray pulsed injection becomes important. IR thermography has been used for monitoring of temperature profile of the catalyst surface simultaneously with product analysis. The heat flux from the plate-type heater to the catalyst has been estimated using a rapid temperature recording and thermocouple arrangement. The estimated heat flux under transient conditions was in the range of 10-15 kW/m(2), which equates the requirement for endothermic reactions to the injection frequency of 0.5 Hz, as used in this study. The analysis of temperature profiles, reaction products over two different supports namely activated carbon cloth and alumite, reveals that the more conductive support such as alumite is more suitable for dehydrogenation of cyclohexane.

Preparation of highly dispersed RhPt alloy catalysts in mesoporous silica using supercritical carbon dioxide and selective synthesis of ethane in butane hydrogenolysis.

RhPt alloy catalysts were prepared in mesoporous silica using supercritical carbon dioxide in impregnation to achieve high dispersion with controlled morphology; catalytic activity and ethane selectivity are enhanced in butane hydrogenolysis.

Zero-CO2 emission and low-crossover 'rechargeable' PEM fuel cells using cyclohexane as an organic hydrogen reservoir.

High performance (open circuit voltage = 920 mV, maximum power density = 14-15 mW cm(-2)) of the PEM fuel cell was achieved by using cyclohexane as a fuel with zero-CO2 emission and lower-crossover through PEM than with a methanol-based fuel cell.

Highly stable performance of catalytic methane dehydrocondensation towards benzene on Mo/HZSM-5 by a periodic switching treatment with H2 and CO2.

Excellent stability and high catalytic activity of methane dehydrocondensation towards benzene and naphthalene on Mo/HZSM-5 were achieved at 1023-1073 K by a periodic H2 or CO2 switching operation, owing to the efficient removal of coke deposition.

C-S bond cleavage of pyridine-2-thiol: a new functionality of quadruply bridged dinuclear platinum and palladium complexes.

Treatment of pyridine-2-thiol (pytH) with H(2) (60 atm) in the presence of 5-methylpyridine-2-thiolate (5-mpyt)-bridged dinuclear Pt(III), Pt(II), or Pd(II) complexes (1 mol %) in DMF at 150 degrees C for 72 h leads to the formation of pyridine in 3-51% yield. From the (1)H NMR study of the exchange reactions and of the products under D(2) pressure, it is suggested that the catalytic reaction involves bimetallic activation of the pyt ligand followed by the liberation of pyridine and H(2)S.

Ruthenium Carbonyl Clusters in Faujasite Cages: Synthesis and Characterization.

The synthesis of the intrafaujasite anchoring of ruthenium carbonyl clusters involves the adsorption of metal carbonyl species or metal ion exchange into faujasite cages followed by reductive carbonylation under an atmosphere of CO and H(2). The characterization of the structure and properties of these samples was based on a multianalytical approach, including FT-IR, UV-vis, PXRD, and EXAFS spectroscopies, CO/H(2) gas chemisorption, and (13)CO isotopic exchange. From this study, several key points emerge. (a) [Ru(3)(CO)(12)] clusters thermally diffused into dehydrated faujasite cages. (b) [Ru(3)(CO)(12)] guests in Na(56)Y were thermally activated, in a hydrogen atmosphere, generating intrafaujasite [H(4)Ru(4)(CO)(12)]. (c) Hexammineruthenium(III) complexes in Na(56)X and Na(56)Y underwent progressive thermal activation, in a CO and H(2) atmosphere. The generation process was considered to occur through conversion of the intermediates [Ru(NH(3))(5)(CO)](2+) and Ru(I)(CO)(3) to [Ru(6)(CO)(18)](2)(-). (d) A rapid (13)CO/(12)CO isotopic exchange was found to reversibly occur for [Ru(6)(CO)(18)](2)(-)/Na(56)X under H(2) coexistence. (e) Internal and external confinement of ruthenium carbonyl clusters were compared. (f) Oxidation fragmentation under an O(2) atmosphere and reductive regeneration under a CO and H(2) atmosphere were found to reversibly occur for [Ru(6)(CO)(18)](2)(-) guests. (g) Intrafaujasite anchoring of ruthenium carbonyl clusters showed a strong interaction with the extraframework Na(+) alpha-cage cations, through involvement of the oxygen end of the bridging or equatorial terminal carbonyl ligands.