An Incremental Sit-to-Stand Exercise for Evaluating Physical Capacity in Older Patients with Type 2 Diabetes.

Exercise is recommended for older patients with type 2 diabetes mellitus (T2DM), and increased physical activity contributes to better management of their condition. The conventional exercise test with treadmill or cycle ergometer (CE) for assessing physical capacity, such as peak oxygen uptake (VO2) and anaerobic threshold (AT), is not always usable for older patients with T2DM. The incremental sit-to-stand (ISTS) exercise is an incremental exercise test using external signals to control the sit-to-stand rate in a given time frame and can be performed in a small space using only a chair. This study aimed to examine the validity of the physical capacity assessment during the ISTS exercise, based on the relationships between the ISTS performance, peak VO2, AT on ISTS exercise and CE test, in older patients with T2DM. Twenty-two patients with T2DM (10 men, 12 women; mean age, 68.0 years; range, 61-77 years) performed ISTS exercise (according to an existing protocol) and CE test in a randomized manner. Peak VO2, AT, and completion time were determined for the ISTS exercise and CE test. Peak VO2 during ISTS exercise was significantly associated with that during the CE test (r = 0.89, p < 0.01). The completion time on the ISTS exercise was significantly associated with peak VO2 (r = 0.80, p < 0.01) and AT on the ISTS exercise (r = 0.78, p < 0.01). The ISTS exercise is a useful tool to determine the physical capacity and estimate peak VO2 and AT in older people with T2DM.

Validity and reproducibility of an incremental sit-to-stand exercise test in healthy middle-aged individuals.

[Purpose] We aimed to evaluate the validity and reproducibility of the incremental sit-to-stand exercise test for aerobic fitness evaluation in healthy middle-aged individuals. [Participants and Methods] Thirteen healthy middle-aged individuals randomly underwent the incremental sit-to-stand exercise and cycle ergometer tests, and the peak oxygen uptake was measured during both tests. Pearson's correlation coefficients were used to assess the strength of the association between the peak oxygen uptake measured during the aforementioned tests. Intraclass correlation coefficients with 95% confidence intervals for peak oxygen uptake obtained during the first, second, and third incremental sit-to-stand exercise tests were used to determine the reproducibility of this test. [Results] The peak oxygen uptake measured during the incremental sit-to-stand exercise test was strongly associated with that measured during the cycle ergometer test (r=0.86). The intraclass correlation coefficients (95% confidence intervals) used to verify the association of the peak oxygen uptake between the first and the second incremental sit-to-stand exercise tests and between the second and third incremental sit-to-stand exercise tests were 0.92 (0.66-0.99) and 0.96 (0.82-0.99), respectively. [Conclusion] The incremental sit-to-stand exercise test is a valid and reproducible tool to evaluate aerobic fitness in healthy middle-aged individuals.

Infant Suffocation Incidents Related to Co-Sleeping or Breastfeeding in the Side-Lying Position in Japan.

Co-sleeping and breastfeeding in the side-lying position have recently been pointed out as risk factors for suffocation in sleeping infants; however, there is no actual report on an "incident." "Incident" is defined as a tense or sobering experience without a consequential fatal suffocation accident. It is important to understand infant suffocation incidents to prevent accidents during co-sleeping and breastfeeding in the side-lying position. We investigated factors and frequency of infant suffocation incidents associated with co-sleeping and breastfeeding in the side-lying position using a self-administered questionnaire survey of 895 mothers during their infant's 1-, 4-, or 10-month health checkups. Co-sleeping and breastfeeding in the side-lying position were practiced by 28.3% and 56.0% of mothers, respectively; thus, 84.3% of the mothers surveyed were practicing either co-sleeping or breastfeeding in the side-lying position. Of those who received guidance from a medical professional, 36.1% practiced only co-sleeping while 60.1% practiced only side-lying breastfeeding. In the co-sleeping group, 10.6% had faced infant suffocation incidents, while 13.2% in the breastfeeding in the side-lying position group had faced similar incidents. Regarding factors associated with suffocation incidents while co-sleeping, the frequency of occurrence was significantly more in mothers of 1-month and 4-month-old infants compared with those of 10-month-old infants. Of mothers who faced suffocation incidents while breastfeeding in the side-lying position, 45% also had faced similar incidents while co-sleeping. These results demonstrate the importance of thoroughly educating mothers about the risks associated with co-sleeping and breastfeeding in the side-lying position for preventing infant suffocation.

Development of an Incremental Sit-to-Stand Exercise for Aerobic Fitness Evaluation.

Incremental sit-to-stand exercise (ISTS) is an incremental exercise test using external signals to control the sit-to-stand rate in a given time frame. This study aimed to investigate the concurrent validity and reproducibility of the ISTS in aerobic fitness evaluation among healthy elderly women. Sixteen elderly women performed the ISTS and cycle ergometer test at 3-day to 2-week intervals, and six of the participants performed the ISTS twice. Peak oxygen uptake (VO2), peak heart rate and completion time on the ISTS and cycle ergometer test were determined. Measured peak VO2 on the cycle ergometer test was significantly related to the peak VO2 (r=0.80, P<0.05) and the completion time (r=0.65, P<0.05) on the ISTS. The intraclass correlation coefficients were 0.96 for peak VO2 values and 0.91 for the completion time values during the two ISTSs. In conclusion, the ISTS is a valid, reproducible and safe test for aerobic fitness evaluation in healthy elderly women.

Effect of Different Seat Heights during an Incremental Sit-To-Stand Exercise Test on Peak Oxygen Uptake in Young, Healthy Women.

'Sit-to-stand' exercise uses the repetitive motion of standing up and sitting down in a chair, a common activity of daily living. A new assessment using an incremental sit-to-stand exercise test employs an external sound to control the speed of standing-up and allows increases in work rate. The aims of the study were to examine the effect of different seat heights on peak oxygen uptake (peak VO2) during an incremental sit-to-stand exercise and to assess any difference between peak VO2 values during incremental sit-to-stand exercise compared with a cycle ergometer test. Thirteen healthy young women (age: 23.1 ± 2.6 years, height: 1.61 ± 0.06 m, body mass: 51.9 ± 7.4 kg·m-2) participated in four incremental sit-to-stand tests with different seat heights and cycle tests in random order. The seat heights were adjusted to 100%, 80%, 120%, and 140% of knee height distance (100%, 80%, 120%, and 140% incremental sit-to-stand exercise, respectively). The peak VO2 and completion time were measured during incremental sit-to-stand and cycle ergometer tests, and repeated-measures analysis of variance and Student's paired t-test with Holm's method were used to evaluate differences between these variables. The peak VO2 values increased by about 10-12 mL·min-1·kg-1 as the seat height on the ISTS decreased over a 60% range of lower leg lengths. The peak VO2 values on the 80%, 100%, 120%, and 140% incremental sit-to-stand tests were about 11%, 25%, 40%, and 50% lower than that on the cycle ergometer test, respectively. The peak VO2 on the incremental sit-to-stand test increased as seat height decreased. These findings are useful to determine which seat height on the incremental sit-to-stand tests test is suitable for different populations.

Validity and Reproducibility of an Incremental Sit-To-Stand Exercise Test for Evaluating Anaerobic Threshold in Young, Healthy Individuals.

Sit-to-stand exercise (STS) is a common activity of daily living. The objectives of the present study were: 1) to assess the validity of aerobic fitness measurements based on anaerobic thresholds (ATs), during incremental sit-to-stand exercise (ISTS) with and without arm support compared with an incremental cycle-ergometer (CE) test; and 2) to examine the reproducibility of the AT measured during the ISTSs. Twenty-six healthy individuals randomly performed the ISTS and CE test. Oxygen uptakes at the AT (AT-VO2) and heart rate at the AT (AT-HR) were determined during the ISTSs and CE test, and repeated-measures analyses of variance and Tukey's post-hoc test were used to evaluate the differences between these variables. Pearson correlation coefficients were used to assess the strength of the relationship between AT-VO2 and AT-HR during the ISTSs and CE test. Data analysis yielded the following correlations: AT-VO2 during the ISTS with arm support and the CE test, r = 0.77 (p < 0.05); AT-VO2 during the ISTS without arm support and the CE test, r = 0.70 (p < 0.05); AT-HR during the ISTS with arm support and the CE test, r = 0.80 (p < 0.05); and AT-HR during the ISTS without arm support and the CE test, r = 0.66 (p < 0.05). The AT-VO2 values during the ISTS with arm support (18.5 ± 1.9 mL·min(-1)·kg(-1)) and the CE test (18.4 ± 1.8 mL·min(-1)·kg(-1)) were significantly higher than those during the ISTS without arm support (16.6 ± 1.8 mL·min(-1)·kg(-1); p < 0.05). The AT-HR values during the ISTS with arm support (126 ± 10 bpm) and the CE test (126 ± 13 bpm) were significantly higher than those during the ISTS without arm support (119 ± 9 bpm; p < 0.05). The ISTS with arm support may provide a cardiopulmonary function load equivalent to the CE test; therefore, it is a potentially valid test for evaluating AT-VO2 and AT-HR in healthy, young adults. Key pointsThe ISTS is a simple test that varies only according to the frequency of standing up, and requires only a small space and a chair.The ISTS with arm support is valid and reproducible, and is a safe test for evaluating AT in healthy young adults.For evaluating the AT, the ISTS may serve as a valid alternative to conventional CPX, using either a cycle ergometer or treadmill, in cases where the latter methods are difficult to implement.

The Effect of Different Standing up Frequencies in Sit-to-stand Exercise on Oxygen Uptake.

[Purpose] The aim of this study was to investigate the steady state of oxygen uptake (VO2) at several standing up frequencies to clarify whether workload in the sit-to-stand exercise (STSE) is greater than the anaerobic threshold (AT). [Subjects] Ten healthy young subjects performed the STSE. [Methods] In the STSE, subjects stood up and sat down without using their arms to push-off from the chair at standing up frequencies of 6, 12, 18, 24, 30, and 36 times per minutes. Subjects exercised for 5 minutes at each frequency with 5 minutes of rest between each consecutive frequency trial. The steady state of VO2 was evaluated by the difference in the VO2 between the 3rd and 5th min at each frequency. The correlation between the VO2 of the STSE and the standing up frequency was analyzed. [Results] At standing up frequencies greater than 24 times/min, the steady state of VO2 could not be confirmed. The relationship between the standing up frequency (at less than 24 times/min) and VO2 was strong (r=0.94). [Conclusion] The STSE may be a potentially useful test for determining AT and predicting the physical capacity of patients.

Reduction of the extra-column band dispersion by a slow transport and splitting of a sample band in isocratic reversed-phase liquid chromatography.

Sample introduction method was studied to reduce the extra-column effect in reversed-phase HPLC. Slow transport of a sample band (SToSB) in the pre-column space followed by the introduction of the band into the column at a near-optimum flow rate resulted in larger plate counts for a 1.0 mmID, 5 cm long column as much as 1.4-1.6 times for solutes with a retention factor (k) of 0.5-1.8 compared to a conventional elution method. Further reduction of the extra-column effect was possible by orthogonally splitting the sample band (SplSB) by flow switching during its slow transport followed by the introduction of the leading part of the band into the column. In this case, increased plate counts of up to 2-3 times for solutes with k of 0.5-1.8 were observed for a 1.0 mmID, 5 cm column. The sample introduction method, SToSB in the injector and the pre-column tube of a few µL, was found to reduce the extra-column band variance by 0.4-0.5 µL2 for an UHPLC system with the extra-column volume (Vextra) of ca. 4.6 µL and the system variance (σextra2) of 1.1 µL2 at flow rate of 100 µL/min, while SToSB and subsequent SplSB were found to be more effective, reducing σextra2 by about 0.8 µL2. With an UHPLC instrument with Vextra of about 10 µL and σextra2 of ca. 3.6 µL2 at flow rate of 300 µL/min, 1.4-2.1 times as many plate counts were observed with SToSB and SplSB compared to the normal elution method for early-eluting solutes with k=0.25-1.7 for a column, 2.1 mmID, 5 cm long. With this UHPLC instrument, SToSB and/or SplSB resulted in the reduction of σextra2 by 1.2-2.2 µL2.

Test compounds for detecting the silanol effect on the elution of ionized amines in reversed-phase LC.

The effectiveness of several basic compounds for testing silica-based stationary phases was reviewed by applying them to recent columns for reversed-phase HPLC. Most octadecylsilylated (C18) stationary phases, prepared as a base-deactivated material from high-purity silica gel with endcapping, provided excellent peak shape and column efficiency for the bases including benzylamine and amitriptyline that once caused problems and were subsequently employed for testing silanol activities. However, a cyclic tertiary amine, dextrometorphan, was eluted as an acceptable peak from only a few columns at neutral pH. Such a more sensitive probe is expected to contribute to further improvement of the stationary phase for reversed-phase HPLC.

Cough Strength Is an Indicator of Aspiration Risk When Restarting Food Intake in Elderly Subjects With Community-Acquired Pneumonia.

BACKGROUND: The incidence of community-acquired pneumonia (CAP) is relatively high in elderly subjects. Cough peak flow (CPF) is an objective indicator of cough strength, and CPF evaluation might be useful to assess whether food intake can be restarted. We aimed to examine whether cough strength assessed with CPF can be used as an indicator of the aspiration risk when restarting food intake in elderly subjects with CAP. METHODS: This cross-sectional study included 82 elderly subjects with CAP between August 2016 and March 2018. CPF was measured using a peak flow meter, and we performed the repetitive saliva-swallowing test (RSST), which is a videoendoscopic evaluation of swallowing and is used to assess dysphagia and aspiration. Receiver operating characteristic (ROC) curve analysis was performed. The cutoff value was determined, and the area under the ROC was calculated. RESULTS: The areas under the RSST and CPF curves were 0.87 and 0.83, respectively. The RSST value for identifying the aspiration risk was 2.5 swallows. The sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio were 70.0%, 71.7%, 2.5, and 0.42, respectively. The CPF for identifying the aspiration risk was 190 L/min. The sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio were 82.6%, 69.4%, 2.7, and 0.25, respectively. CONCLUSIONS: Our findings suggest that cough strength assessed with CPF can be used as an indicator of the aspiration risk when restarting food intake in elderly subjects with CAP and that CPF evaluation is not inferior to the RSST. However, CPF evaluation should be performed together with swallowing screening tests to determine the aspiration risk.

Isometric knee extension force in Japanese type 2 diabetic patients without apparent diabetic polyneuropathy: Data from the Multicenter Survey of the Isometric Lower Extremity Strength in Type 2 Diabetes study.

OBJECTIVES: To determine standard reference values for isometric knee extension force using a cohort of Japanese type 2 diabetic patients without diabetic polyneuropathy. METHODS: Patient data were collected from the Multicenter Survey of the Isometric Lower Extremity Strength in Type 2 Diabetes study and compared with previously published data of healthy control subjects. In total, we enrolled 898 patients with type 2 diabetes aged 30-87 years, who did not have diabetic polyneuropathy. The control group included 510 healthy subjects aged 30-88 years. Maximum isometric knee extension force (KEF) values were obtained by using a hand-held dynamometer with belt stabilization. In addition, KEF (kgf) was adjusted for bodyweight (kg) to calculate %KEF. RESULTS: KEF and %KEF decreased with age in both patients with diabetes and healthy control subjects. The mean values of KEF and %KEF in patients with diabetes were reduced by 9.7% and 20.8%, respectively, in males, and by 11.6% and 23.0%, respectively, in females compared to the values in healthy control subjects. CONCLUSION: KEF and %KEF in patients with type 2 diabetes without diabetic polyneuropathy may reduce by approximately 10% and 20%, respectively, compared to these values in healthy control subjects. This study provides reference values for isometric KEF with respect to sex in a population covering a wide age range.

Diabetic polyneuropathy is a risk factor for decline of lower extremity strength in patients with type 2 diabetes.

AIMS/INTRODUCTION: The present study elucidated the effect of diabetic polyneuropathy (DPN) on lower extremity strength in a wide age range of type 2 diabetes patients. MATERIALS AND METHODS: Participants (n = 1,442) were divided into three age groups (30-49 years, 50-69 years and 70-87 years), and comparisons were made separately for each sex. Lower extremity strength was measured in terms of knee extension force (KEF) with a hand-held dynamometer. KEF was compared according to the presence or absence of DPN. Furthermore, the effect of DPN on KEF with other diabetic complications (diabetic retinopathy and diabetic nephropathy), diabetes status (diabetes duration and glycated hemoglobin) and habitual behavior (regular exercise, smoking and drinking behaviors) as explanatory variables was analyzed using multiple regression analysis in several models. RESULTS: The frequency of DPN differed among age groups, ranging from 14.3 to 49.6%, and increasing with age. There was no significant difference in KEF between patients aged 30-49 years with and without DPN. However, among both men and women aged 50-69 years and 70-87 years, patients with DPN showed significantly diminished KEF (11.0-12.9% and 11.9-16.6%, respectively) compared with those without DPN (P < 0.01-0.001). In women aged 50-69 years and 70-87 years, and in men aged 50-69 years, DPN was a significant explanatory variable for KEF in all multiple regression analysis models. CONCLUSION: DPN might reinforce a KEF decline in middle-aged and elderly type 2 diabetes patients.

Regular exercise behavior is related to lower extremity muscle strength in patients with type 2 diabetes: Data from the Multicenter Survey of the Isometric Lower Extremity Strength in Type 2 Diabetes study.

Owing to several contributing factors, continuation of exercise therapy is difficult for patients with type 2 diabetes. One potential factor that has not been well examined is the influence of muscle strength on regular exercise behavior. We examined the relationship between regular exercise behavior and knee extension force (KEF) in 1,442 patients with type 2 diabetes. In sex-specific univariate analysis, KEF was significantly higher in patients who regularly exercised than in patients who did not regularly exercise. However, age, but not exercise behavior, was significantly different between KEF quartiles. Accordingly, KEF and age might strongly influence exercise behavior. In the multivariate analyses using age and other parameters as covariates, KEF was a significant explanatory variable of regular exercise in both men and women, suggesting that muscle strength could influence regular exercise behavior.

Reduction of the extra-column band dispersion by a slow transport of a sample band from the injector to the column in isocratic reversed-phase liquid chromatography.

Extra-column band dispersion during the transport of a sample band from the injector to the column can be reduced by a flow rate program starting with a low flow rate until the sample band has approached to, or just entered into the column, followed by an increased flow rate suitable for the solute separation in the column. Such a sample introduction method increased the plate counts of a 50 mm long column, 1.0 or 2.1 mmID, especially for early-eluting solutes by up to several times compared to a conventional elution method, when a 0.254 mmID, 15.2 cm connection tubing was used. Increase in plate counts of up to 50-70% was possible for solutes with retention factors smaller than 1.0 for the columns connected with a 0.13 mmID, 15 cm tube. The method also seems to reduce the contribution of the void space at the column inlet to the band dispersion. The elution method including a slow transport of the sample band in the pre-column space of 10 µL or less may require a little longer separation time than normal elution, but it was shown to be effective for increasing the observed efficiency of a small column for solutes with small retention factors.

Comparison of the kinetic performance of different columns for fast liquid chromatography, emphasizing the contributions of column end structure.

The kinetic performance of five chromatographic columns designed for fast liquid chromatography with different column packing materials - including fully porous (2.0 and 1.9µm particles), core-shell (2.6µm particles) or monolithic packings - with identical column dimensions (2.1×50mm) was tested. Since the tested monolithic column showed systematically better efficiency for early eluting compounds than the packed columns, an additional band broadening effect was suspected for the packed columns. The effects of the presence of the frits and the bed heterogeneity of the columns near the frits were characterized by a column-reversal method. It has been shown that significant differences - even 20-25% difference in efficiency - can exist between the two ends of the packed columns, while the monolithic column shows rather similar performance at either column end.

Association between physical performance and cardiovascular events in patients with coronary artery disease: protocol for a meta-analysis.

BACKGROUND: Physical performance such as muscle strength or walking speed of patients with coronary artery disease (CAD) is lower than that of people who do not have CAD and is related to mortality and re-admission rates. Recent studies have shown that skeletal muscle strength, such as grip strength, was closely associated with cardiac events. Physical performance testing is quick, safe, and inexpensive and provides a reliable assessment tool for routine clinical practice. The aim of this meta-analysis is to clarify the association between physical performance testing and the risk of cardiovascular events and mortality. METHODS/DESIGN: This meta-analysis will include male and female participants of any age in community settings who have a history of the following conditions or procedures: myocardial infarction, or coronary revascularization (coronary artery bypass grafting, percutaneous transluminal coronary angioplasty, or coronary artery stent), angina pectoris, heart failure, heart transplant, or coronary artery disease defined by angiography. We will search EMBASE and MEDLINE, PubMed, and the Cochrane Library with no limitations on date, language, document type, or publication status. Identified studies will be prospective and retrospective cohort studies. Physical performance will be defined as upper extremity strength, lower extremity strength, walking speed, or other performance scale. Six review authors will independently extract study characteristics from included studies. Participants will be divided into subgroups according to age (middle-aged <65 years and elderly ≥ 65 years), diagnosis (coronary artery disease and heart failure) and follow-up time (up to 12 months and over 12 months). We will pool hazard ratios of Cox proportional hazard models after logarithmic transformation and perform the meta-analysis by using inverse-variance method. DISCUSSION: To our knowledge, this meta-analysis will be the first report to assess the association between physical performance and cardiovascular events in CAD patients. We hope that these findings may help to estimate the prognosis for CAD patients in clinical practice. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42015020886.

Distinction of synthetic dl-α-tocopherol from natural vitamin E (d-α-tocopherol) by reversed-phase liquid chromatography. Enhanced selectivity of a polymeric C18 stationary phase at low temperature and/or at high pressure.

Separation of diastereomers of dl-α-tocopherol was studied by reversed-phase liquid chromatography using three types of stationary phases, polymeric ODS, polymeric C30, and monomeric ODS. Polymeric ODS stationary phase (Inertsil ODS-P, 3mmID, 20cm) was effective for the separation of the isomers created by the presence of three chiral centers on the alkyl chain of synthetic dl-α-tocopherol. Considerable improvement of the separation of isomers was observed on ODS-P phase at high pressure and at low temperature. Complete separation of four pairs of diastereomers was achieved at 12.0°C, 536bar, while three peaks were observed when the separation was carried out either at 12.0°C at low pressure or at 20°C at 488bar. Higher temperature (30.0°C) with the ODS-P phase resulted in only partial separation of the diastereomers even at high pressure. Only slight resolution was observed for the mixture of diastereomers with the C30 stationary phase (Inertsil C30) at 12.0°C and 441bar, although the stationary phase afforded greater resolution for ß- and γ-tocopherol than ODS-P. A monomeric C18 stationary phase did not show any separation at 12.0°C and 463bar. The results suggest that the binding site of the polymeric ODS-P phase is selective for flexible alkyl chains that provided the longest retention for the natural form, (R,R,R) form, and the enantiomer, (S,S,S) form, of dl-α-tocopherol.

Efficiency of short, small-diameter columns for reversed-phase liquid chromatography under practical operating conditions.

Prototype small-size (1.0mm I.D., 5cm long) columns for reversed-phase HPLC were evaluated in relation to instrument requirements. The performance of three types of columns, monolithic silica and particulate silica (2µm, totally porous and 2.6µm, core-shell particles) was studied in the presence of considerable or minimal extra-column effects, while the detector contribution to band broadening was minimized by employing a small size UV-detector cell (6- or 90nL). A micro-LC instrument having small system volume (<1µL) provided extra-column band variance of only 0.01-0.02µL(2). The three columns generated about 8500 theoretical plates for solutes with retention factor, k>1-3 (depending on the column), in acetonitrile/water mobile phase (65/35=vol/vol) at 0.05mL/min, with the instrument specified above. The column efficiency was lower by up to 30% than that observed with a 2.1mm I.D. commercial column. The small-size columns also provided 8000-8500 theoretical plates for well retained solutes with a commercial ultrahigh-pressure liquid chromatography (UHPLC) instrument when extra-column contributions were minimized. While a significant extra-column effect was observed for early eluting solutes (k<2-4, depending on column) with methanol/water (20/80=vol/vol) as weak-wash solvent, the use of methanol/water=50/50 as wash solvent affected the column efficiency for most analytes. The results suggest that the band compression effect by the weak-wash solvent associated with partial-loop injection may provide a practical means to reducing the extra-column effect for small-size columns, while the use of an instrument with minimum extra-column effect is highly desirable.

Effect of pressure on the selectivity of polymeric C18 and C30 stationary phases in reversed-phase liquid chromatography. Increased separation of isomeric fatty acid methyl esters, triacylglycerols, and tocopherols at high pressure.

A high-density, polymeric C18 stationary phase (Inertsil ODS-P) or a polymeric C30 phase (Inertsil C30) provided improved resolution of the isomeric fatty acids (FAs), FA methyl esters (FAMEs), triacylglycerols (TAGs), and tocopherols with an increase in pressure of 20-70MPa in reversed-phase HPLC. With respect to isomeric C18 FAMEs with one cis-double bond, ODS-P phase was effective for recognizing the position of a double bond among petroselinic (methyl 6Z-octadecenoate), oleic (methyl 9Z-octadecenoate), and cis-vaccenic (methyl 11Z-octadecenoate), especially at high pressure, but the differentiation between oleic and cis-vaccenic was not achieved by C30 phase regardless of the pressure. A monomeric C18 phase (InertSustain C18) was not effective for recognizing the position of the double bond in monounsaturated FAME, while the separation of cis- and trans-isomers was achieved by any of the stationary phases. The ODS-P and C30 phases provided increased separation for TAGs and ß- and γ-tocopherols at high pressure. The transfer of FA, FAME, or TAG molecules from the mobile phase to the ODS-P stationary phase was accompanied by large volume reduction (-30∼-90mL/mol) resulting in a large increase in retention (up to 100% for an increase of 50MPa) and improved isomer separation at high pressure. For some isomer pairs, the ODS-P and C30 provided the opposite elution order, and in each case higher pressure improved the separation. The two stationary phases showed selectivity for the isomers having rigid structures, but only the ODS-P was effective for differentiating the position of a double bond in monounsaturated FAMEs. The results indicate that the improved isomer separation was provided by the increased dispersion interactions between the solute and the binding site of the stationary phase at high pressure.