Cross-validation of Peak Oxygen Consumption Prediction Models From OMNI Perceived Exertion.

This study cross-validated statistical models for prediction of peak oxygen consumption using ratings of perceived exertion from the Adult OMNI Cycle Scale of Perceived Exertion. 74 participants (men: n=36; women: n=38) completed a graded cycle exercise test. Ratings of perceived exertion for the overall body, legs, and chest/breathing were recorded each test stage and entered into previously developed 3-stage peak oxygen consumption prediction models. There were no significant differences (p>0.05) between measured and predicted peak oxygen consumption from ratings of perceived exertion for the overall body, legs, and chest/breathing within men (mean±standard deviation: 3.16±0.52 vs. 2.92±0.33 vs. 2.90±0.29 vs. 2.90±0.26 L·min(-1)) and women (2.17±0.29 vs. 2.02±0.22 vs. 2.03±0.19 vs. 2.01±0.19 L·min(-1)) participants. Previously developed statistical models for prediction of peak oxygen consumption based on subpeak OMNI ratings of perceived exertion responses were similar to measured peak oxygen consumption in a separate group of participants. These findings provide practical implications for the use of the original statistical models in standard health-fitness settings.

[Bleeding in patients receiving dual antiplatelet therapy after acute coronary syndrome - significance, prevention and interdisciplinary management]. / Interdisziplinäres Management von Blutungen unter dualer antithrombozytärer Therapie nach akutem Koronarsyndrom.

For secondary prevention of acute coronary syndrome, guidelines recommend dual antiplatelet therapy with acetylsalicylic acid and a P2Y12 receptor antagonist such as clopidogrel, prasugrel or ticagrelor for a period of 12 months. Premature discontinuation of dual antiplatelet therapy is associated with an increased risk of ischaemic events. However, antiplatelet therapy is also associated with an increased risk of bleeding that should not be under- or overestimated. To ensure an optimal care of patients receiving dual antiplatelet therapy after an acute coronary syndrome, an interdisciplinary group of experienced experts in the fields of cardiology, cardiac surgery, gastroenterology, anaesthesiology, intensive care and haemostaseology gathered bleeding-related information and developed recommendations relevant to daily clinical practice. These include the significance of bleeding events in the course of treatment, measures for bleeding prevention and the adequate care of patients with bleedings.

Drug allergies documented in electronic health records of a large healthcare system.

BACKGROUND: The prevalence of drug allergies documented in electronic health records (EHRs) of large patient populations is understudied. OBJECTIVE: We aimed to describe the prevalence of common drug allergies and patient characteristics documented in EHRs of a large healthcare network over the last two decades. METHODS: Drug allergy data were obtained from EHRs of patients who visited two large tertiary care hospitals in Boston from 1990 to 2013. The prevalence of each drug and drug class was calculated and compared by sex and race/ethnicity. The number of allergies per patient was calculated and the frequency of patients having 1, 2, 3…, or 10+ drug allergies was reported. We also conducted a trend analysis by comparing the proportion of each allergy to the total number of drug allergies over time. RESULTS: Among 1 766 328 patients, 35.5% of patients had at least one reported drug allergy with an average of 1.95 drug allergies per patient. The most commonly reported drug allergies in this population were to penicillins (12.8%), sulfonamide antibiotics (7.4%), opiates (6.8%), and nonsteroidal anti-inflammatory drugs (NSAIDs) (3.5%). The relative proportion of allergies to angiotensin-converting enzyme (ACE) inhibitors and HMG CoA reductase inhibitors (statins) have more than doubled since early 2000s. Drug allergies were most prevalent among females and white patients except for NSAIDs, ACE inhibitors, and thiazide diuretics, which were more prevalent in black patients. CONCLUSION: Females and white patients may be more likely to experience a reaction from common medications. An increase in reported allergies to ACE inhibitors and statins is noteworthy.

Standard Information Models for Representing Adverse Sensitivity Information in Clinical Documents.

BACKGROUND: Adverse sensitivity (e.g., allergy and intolerance) information is a critical component of any electronic health record system. While several standards exist for structured entry of adverse sensitivity information, many clinicians record this data as free text. OBJECTIVES: This study aimed to 1) identify and compare the existing common adverse sensitivity information models, and 2) to evaluate the coverage of the adverse sensitivity information models for representing allergy information on a subset of inpatient and outpatient adverse sensitivity clinical notes. METHODS: We compared four common adverse sensitivity information models: Health Level 7 Allergy and Intolerance Domain Analysis Model, HL7-DAM; the Fast Healthcare Interoperability Resources, FHIR; the Consolidated Continuity of Care Document, C-CDA; and OpenEHR, and evaluated their coverage on a corpus of inpatient and outpatient notes (n = 120). RESULTS: We found that allergy specialists' notes had the highest frequency of adverse sensitivity attributes per note, whereas emergency department notes had the fewest attributes. Overall, the models had many similarities in the central attributes which covered between 75% and 95% of adverse sensitivity information contained within the notes. However, representations of some attributes (especially the value-sets) were not well aligned between the models, which is likely to present an obstacle for achieving data interoperability. Also, adverse sensitivity exceptions were not well represented among the information models. CONCLUSIONS: Although we found that common adverse sensitivity models cover a significant portion of relevant information in the clinical notes, our results highlight areas needed to be reconciled between the standards for data interoperability.

[Masked stress-induced arterial hypertension]. / Maskierte, Stress-induzierte arterielle Hypertonie.

BACKGROUND: Patients who suffer from masked stress-induced arterial hypertension have normal blood pressure values, when measured in the doctor's office, but show elevated values in their everyday life or at work. The two cases, described here, underline the importance of optimal blood pressure measurement and the use of state-of-the-art methods as the basis for recognition and correct classification of this kind of hypertension and for characterization of individual blood pressure profile. This diagnostics is necessary for every therapeutic decision. HISTORY: Case 1: A now 53-year-old patient first came in six years ago with incidental cardiac dysrhythmia. He stated to suffer from substantial stress at work. Three years previously, an ambulatory blood pressure monitoring (ABPM) showed normal blood pressure levels: daytime mean of 122/78 mmHg (<135/85). Case 2: A 42-year-old patient reported to have had elevated blood pressure for a year and a half, as seen during occasional self-measurements. He, too, suffers from substantial stress at work and, in addition, has a family predisposition for hypertension. INVESTIGATIONS: Case 1: INVESTIGATIONS showed paroxysmal atrial fibrillation with hypertensive heart disease. Repeated blood pressure measures (brachial and aortal) in the clinic showed normal values when the patient was under standardized exercise testing or at rest. Ambulatory blood pressure monitoring (ABPM) revealed a moderate systolic and a mild diastolic hypertension. Case 2: Both measurements during exercise and at rest showed normal blood pressure values. ABPM showed moderate systolic and severe diastolic hypertension (daytime mean of 150/103 mmHg). Central/aortal blood pressure was also normal (118 mmHg) when measured in the clinic, but severely elevated during ABPM (145 mmHg < 130). There was no hypertension-induced organ damage yet. TREATMENT: Case 1: Under antihypertensive medication blood pressure has been stabilized at the normal level (ABPM). Atrial fibrillation was permanently removed by catheter ablation. Case 2: According to the patient's wishes, no antihypertensive drug therapy has been initiated yet. The current aim is to normalize the blood pressure by general measures (i.a. stress management). CONCLUSION: Masked stress-induced arterial hypertension can lead to hypertension-induced organ damage. It has to be revealed via ABPM and therapy must be initiated, despite normal blood pressure levels measured in the clinic. Exact characterization of this kind of hypertension with optimal measuring methods is the prerequisite for individual treatment strategies. This applies particularly to masked hypertension, which is often stress-induced and results in high blood pressure under daily routine.

Using models to predict the future: what to do when the data run out?

Although clinical trials often provide "best evidence" comparing the effectiveness of alternative management strategies, such evidence can be limited in duration or in the results reported, causing clinicians and policy analysts to wonder "what if?" Models of the clinical prognosis-often spanning patients' lifetimes (the "long haul")-are perhaps weaker evidence, but can help answer questions about the management of individual patients and place that best evidence into the context of clinical reality.

[Care of hypertensive patients seen by cardiologists: results of the Snapshot Hypertension Registry]. / Der Patient mit arterieller Hypertonie in der kardiologischen Facharztpraxis: Ergebnisse des Snapshot-Hypertonie-Registers. Ein Projekt des Bundesverbandes Niedergelassener Kardiologen (BNK e.V.).

BACKGROUND: The objective of the Snapshot Hypertension Registry (SHR) was to assess the quality of antihypertensive drug treatment in hypertensive patients seen by cardiologists on three consecutive days in December 2005. METHODS: Full data sets were obtained for 7302 patients (89.9% of total returned) seen by 268 cardiologists. Mean age of hypertensive patients was 65.4 +/- 11.2 years, 62 % were male, and 93 % were referred to the cardiologist by a general practitioner. RESULTS: Judging from their casual ("snapshot") blood pressure, 35.3 % were well treated (< 140/90 mm Hg). According to the 24-hour ambulatory blood pressure even a lower rate of hypertensive patients, namely 27.6 %, had their blood pressure well controlled (< 130/80 mm Hg). Of all patients, 24 % were on monotherapy. Only 33.7 % of the patients on monotherapy were normotensive. Of all patients on a combination of drugs 36.9 % were normotensive according to the casual blood pressure measurements. Private patients were prescribed angiotensin receptor blockers more frequently than patients who only had statutory health insurance. CONCLUSIONS: The Snapshot Registry analysis revealed that the casual blood pressure in the majority of hypertensive patients who were reviewing antihypertensive medication was not in the normotensive range. In addition, our data demonstrate that evidence-based antihypertensive medication was often not adequately used in Germany.

Effect of a maximal treadmill test on percent body fat using leg-to-leg bioelectrical impedance analysis in children.

AIM: The purpose of this investigation was to determine the effect of a maximal treadmill exercise test on percent body fat (%BF) in children using leg-to-leg bioelectrical impedance analysis (LBIA) (Tanita Model #TBF-300A). METHODS: Fifty-four children (24 females; 30 males) between 7-10 years of age participated in this study. LBIA measures of %BF were obtained immediately before and within 5 min after completing a maximal oxygen consumption test on a motorized treadmill. RESULTS: No pre- to post-test differences in %BF were observed in either group (mean difference: females 1.6%, males 1.5%). Impedance values significantly decreased postexercise (P < 0.05) in the female subjects. No significant differences were observed for fat mass, fat free mass, total body water or body weight postexercise when compared to pre-exercise values in either group. Correlations (P = 0.0001) of 0.997 were observed between pre- and postexercise measures of %BF. CONCLUSIONS: A maximal treadmill exercise test conducted prior to LBIA has no impact on %BF in children. Therefore, normal daily activities performed prior to LBIA assessment may have a limited impact on LBIA body composition measurement in children. As such, compliance with stringent pretesting exercise guidelines may not be essential when using LBIA to assess %BF in children.

The effect of acute fluid consumption on measures of impedance and percent body fat using leg-to-leg bioelectrical impedance analysis.

OBJECTIVE: To examine the effect of acute fluid consumption on measures of impedance and percent body fat (%BF) using a common leg-to-leg bioelectrical impedance analyzer system. DESIGN: Cross-sectional design with treatment order determined using a counterbalanced assignment. SETTING: University laboratory. SUBJECTS: In total, 21 recreationally active men (mean age 19.7 +/- 1.0 years; body mass index 24.2 +/- 2.3 kg/m2) volunteered to participate in this study. INTERVENTION: Subjects had their body composition assessed on three separate occasions. After an initial baseline body composition measurement, subjects consumed 591 ml of water (H2O), a carbohydrate/electrolyte drink (CHOE), or received nothing, used as the control (CON). Subjects were reassessed 20, 40, and 60 min after baseline (POST). Urine specific gravity (USG) was recorded at baseline and 60 min POST to assess hydration state. RESULTS: There were no significant changes in impedance or total body water (TBW) for any of the measurement time periods after drinking H2O or a CHOE beverage. Body weight (BW) (P < 0.0001) and %BF (P < 0.02) increased significantly 20 min POST and remained elevated at the 40 and 60 min POST time periods. After drinking, USG significantly decreased (P<0.0001) 60 min POST from baseline. For the CON trial, there were no significant changes in BW, %BF, TBW, or USG over time. CONCLUSIONS: Fluid consumption had no effect on lower-body impedance despite causing significant changes in hydration state. A slight overestimation in %BF (approximately 0.5%) was observed due to increased BW in the H20 and CHOE trials. This finding may have little practical significance when assessing body composition by LBIA.

Increased exercise ejection fraction and reversed remodeling after long-term treatment with metoprolol in congestive heart failure: a randomized, stratified, double-blind, placebo-controlled trial in mild to moderate heart failure due to ischemic or idiopathic dilated cardiomyopathy.

BACKGROUND: the effects of long-term administration of beta-blockers on left ventricular (LV) function during exercise in patients with ischemic heart disease (IHD) and idiopathic dilated cardiomyopathy (DCM) are controversial. PATIENTS AND METHODS: patients with stable congestive heart failure (CHF) (New York heart association [NYHA] class II and III) and ejection fraction (EF) < or =0.40 were randomized to metoprolol, 50 mg t.i.d. or placebo for 6 months. Patients were divided into two groups: ischemic heart disease (IHD) and idiopathic dilated cardiomyopathy (DCM). The mean EF was 0.29 in both groups and 92% were taking angiotensin-converting enzyme (ACE) inhibitors. In the IHD group, 84% had suffered a myocardial infarction (MI) and 64% had undergone revascularization at least 6 months before the study. LV volumes were measured by equilibrium radionuclide angiography. Mitral regurgitation was assessed by Doppler echocardiography. All values are changes for metoprolol subtracted by changes for placebo. RESULTS: metoprolol improved LV function markedly both at rest and during sub-maximal exercise in both groups. The mean increase in EF was 0.069 at rest (P<0.001) and 0.078 during submaximal exercise (P<0.001). LV end-diastolic volume decreased by 22 ml at rest (P=0.006) and by 15 ml during exercise (P=0.006). LV end-systolic volume decreased by 23 ml both at rest (P=0.001) and during exercise (P=0.004). Exercise time increased by 39 s (P=0.08). In the metoprolol group, mitral regurgitation decreased (P=0.0026) and only one patient developed atrial fibrillation vs. eight in the placebo group (P=0.01). CONCLUSION: metoprolol improves EF both at rest and during submaximal exercise and prevents LV dilatation in mild to moderate CHF due to IHD or DCM.

OMNI scale perceived exertion at ventilatory breakpoint in children: response normalized.

PURPOSE: The Children's OMNI Scale of Perceived Exertion was used to identify a response normalized rating of perceived exertion (RPE)-Overall, RPE-Legs, and RPE-Chest that corresponds to the ventilatory breakpoint (Vpt) in 8- to 12-yr-old female and male children. METHODS: Subjects were a priori stratified into two fitness groups on the basis of peak oxygen uptake (VO2 peak): average (A) (41.0-49.0 mL x kg(-1) x min(-1); N = 24) and above average (AA) (50.0-58.0 mL x kg(-1) x min(-1); N = 24). Vpt was determined by a progressive cycle ergometer protocol to VO2 peak. RESULTS: A gender effect was not observed for any descriptive or dependent variable. Mean VO2peak for the A group was 1.72 L x min(-1) and for the AA group 2.04 L x min(-1). Vpt corresponded to 64.0% VO2 peak for A and 74.0% VO2peak for AA. RPE-Overall (mean A and AA, 6.1), RPE-Legs (mean A and AA, 7.2), and RPE-Chest (mean A and AA, 4.5) did not differ between the fitness groups. CONCLUSION: Findings indicated that undifferentiated and differentiated RPE-Vpt were similar between female and male children who varied in VO2peak and Vpt. A comparatively stable RPE-Vpt for 8- to 12-yr-old children that vary in VO2peak and Vpt indicates a group normalized perceptual response.

A comparison of leg-to-leg bioelectrical impedance and skinfolds in assessing body fat in collegiate wrestlers.

A comparison of the leg-to-leg bioelectrical impedance (BIA) system and skinfold analysis in estimating % body fat in a large number of National Collegiate Athletic Association (NCAA) collegiate wrestlers was conducted. A series of 5 cross-sectional assessments, including the NCAA Division I and III Championships, were completed throughout the 1998-1999 wrestling season with samples ranging from (N = 90-274). Body density was determined from the 3 skinfold measures using the Lohman prediction equation. BIA measurements were determined using the Tanita body fat analyzer, model 305. Significant correlations between methods ranging from (r = 0.67-0.83, p < 0.001) and low standard error of estimates (SEE) for % body fat ranging from 2.1-3.5% were found throughout the 5 assessment periods. This preliminary study demonstrated that the leg-to-leg bioelectrical impedance system accurately estimated % body fat when compared to skinfolds in a diverse collegiate wrestling population.

Standardized scaling procedures for rating perceived exertion during resistance exercise.

The purpose of this project was to determine the validity of standardized Borg scale instructions and scale anchoring procedures to measure active muscle rating of perceived exertion and overall rating of perceived exertion during resistance exercise. Anchoring procedures were determined for each of 7 exercises before the completion of 2 counterbalanced experimental trials. In one trial, subjects lifted 90% of 1 repetition maximum (1RM) 5 times. In the other, subjects lifted 30% of 1RM 15 times. Adjusted R2 and SEMs were used to determine linearity of Borg 15-category scale responses with respect to repetitions at equal work increments for both the group and the sum of the individuals. Both group and individual responses had high adjusted R2 and low SEM values. These results suggest that the current scaling instructions used with the Borg 15-category scale are valid for use during resistance exercise.

Effect of potassium phosphate supplementation on perceptual and physiological responses to maximal graded exercise.

This investigation evaluated the effect of oral potassium phosphate supplementation on ratings of perceived exertion (RPE) and physiological responses during maximal graded exercise tests (GXT). Eight highly trained endurance runners completed a GXT to anchor the Borg 15-point RPE scale and two double-blind counterbalanced GXTs. Subjects ingested either 4,000 mg x day(-1) of phosphate (PHOS) or a placebo (PLA) for 2 days. Two weeks separated GXTs. Phosphate levels obtained immediately prior to the GXTs were greater in PHOS than PLA. No differences between PHOS and PLA were noted for the submaximal and maximal physiological responses. RPE for the overall body were lower during PHOS than PLA at intensities corresponding to 70-80% of VO2max. This suggests that oral potassium phosphate supplementation mediates perceived exertion during moderately intense exercise.

Peak oxygen consumption and skeletal muscle bioenergetics in African-American and Caucasian men.

OBJECTIVE: To compare peak oxygen consumption (VO2peak) and skeletal muscle oxidative metabolism between nine African-American and nine Caucasian men. METHODS: Subjects performed arm ergometry to exhaustion. On a separate occasion 31phosphorous-nuclear magnetic resonance spectroscopy (31P-NMRS) was used to determine the concentrations of phosphorous (Pi), phosphocreatine (PCr), and the intracellular pH of the flexor carpi radialis before and during 4 min of steady-state, wrist flexion exercise performed at 28% (15 W) of each subject's peak voluntary contraction. RESULTS: The Pi/PCr ratio was used as an indirect measure of skeletal muscle oxidative metabolism. VO2peak was lower in the African-Americans compared with the Caucasians (means +/- SD, 19.4 +/- 3.4 vs 23.3 +/- 4.0 mL x kg(-1) x min(-1)) (P < 0.05). No significant between group difference was noted in the Pi/PCr ratio at rest (0.10 +/- 0.02 both groups). However, resting pH was lower in the African-Americans (6.99 +/- 0.04 vs 7.03 +/- 0.05) (P < 0.05). Exercise caused an increase in the Pi/PCr ratio in the African-Americans (1.06 +/- 0.11), which was higher than the increase observed in the Caucasians (0.50 +/- 0.14) (P < 0.05). pH levels decreased to a lower level during exercise in the African-Americans (6.89 +/- 0.04) than in the Caucasians (6.98 +/- 0.05) (P < 0.05). CONCLUSIONS: This select group of African-American men achieved a lower VO2peak than the Caucasian men. Variations in skeletal muscle oxidative metabolic components may explain this difference.

Gender comparison of RPE at absolute and relative physiological criteria.

PURPOSE: The effect of gender on ratings of perceived exertion for the overall body (RPE-O), chest (RPE-C), legs (RPE-L), and arms (RPE-A (ski)) was determined. METHODS: Comparisons were made at, a) absolute oxygen uptake (VO2, L x min(-1); mL x kg(-1) x min(-1)) and heart rate (HR, b x min(-1)) and b) relative VO2 (%VO2max/peak) and HR (% HRmax/peak) reference criteria. Nine male and 10 female subjects were compared using a perceptual estimation paradigm for treadmill (weight bearing), simulated ski (partial weight bearing), and cycle (nonweight bearing) exercise. RPE was determined by the Borg 15-category scale. RESULTS: For each exercise mode, RPE-O, RPE-L, RPE-A (ski), and RPE-C were higher (P < 0.05) in the female than male cohort when compared at submaximal absolute VO2 criteria. RPE did not differ between female and male cohorts when compared at mode specific relative VO2 criteria. Differences in RPE-O, RPE-L, RPE-A (ski), and RPE-C were not found between female and male subjects when comparisons were made at both absolute and relative HR. Responses were consistent for the three exercise modes. CONCLUSION: RPE did not differ between gender when comparisons were made at relativized VO2 and HR reference criteria at exercise intensities between 70 and 90% of mode specific maximal/peak values.

[Therapy of heart failure. General practice references for individual treatment]. / Therapie der Herzinsuffizienz. Praxistipps für eine individuelle Behandlung.

Cardiac insufficiency is today the most common reason for hospitalizing patients older than 65 years, and is associated with considerable costs for the health care system. The economic consequences (drug costs, hospitalization and costs of early retirement) necessitate close cooperation between family doctor and cardiologist if a rational (evidence based medicine) and cost-optimized treatment is to be achieved. The implementation of the current therapeutic concepts and guidelines issued by the specialist societies has so far been inadequate, in particular due to a misguided approach to budgeting, and the pressure of rising costs. Few diseases are as accessible to a differentiated drug treatment as chronic heart failure. Numerous studies have shown that an optimally adapted and adequately dosed treatment with ACE inhibitors, beta blockers, diuretics, aldosterone antagonists and digitalis is capable, not only of lowering the mortality rate, but also of achieving a significant reduction in morbidity (improved quality of life, shorter hospitalization). The treatment of the chronic forms of cardiac insufficiency is a domain of ambulatory patient care that, with an eye to the multimorbidity of the elderly, requires individually adapted pharmacotherapy.

Children's OMNI scale of perceived exertion: mixed gender and race validation.

PURPOSE: The newly developed Children's OMNI Scale of Perceived Exertion (category range: 0 to 10) was validated using separate cohorts of female and male, African American and white subjects. Each of the four cohorts contained 20 clinically normal, nonobese children, 8-12 yr of age. METHODS: A cross-sectional, perceptual estimation paradigm using a single multi-stage cycle ergometer test protocol was used. Oxygen uptake (VO2; mL x min(-1)), heart rate (HR; beats x min(-1)) and ratings of perceived exertion for the overall body (RPE-Overall), legs (RPE-Legs), and chest (RPE-Chest) were determined at the end of each continuously administered 3-min power output (PO) (i.e., 25, 50, 75, and 100 W) test stage. RESULTS: The range of responses over the four POs for all cohorts was VO2: 290.8 to 1204.0 mL x min(-1); HR: 89.2 to 164.4 beats x min(-1); and RPE-Overall, RPE-Legs, and RPE-Chest: 0.85 to 9.1. First-order correlation and linear regression analyses were performed for each cohort separately and the total sample using a repeated measures paradigm over the four POs. For all correlation/regression paradigms RPE-Overall, RPE-Legs, and RPE-Chest distributed as a positive linear function of both VO2 and HR; r = 0.85 to 0.94; P < 0.01. Differences between RPE-Overall, RPE-Legs, and RPE-Chest were examined with ANOVA for the repeated measures paradigm. RPE-Legs was higher (P < 0.01) than RPE-Chest and RPE-Overall at 25, 50, 75, and 100 W. RPE-Chest did not differ from RPE-Overall at 25 and 50 W but was lower (P < 0.01) than RPE-Overall at 75 and 100 W. CONCLUSION: The psycho-physiological responses provide validity evidence for use of the Children's OMNI Scale over a wide range of dynamic exercise intensities.

Substrate utilization and glucose turnover during exercise of varying intensities in individuals with NIDDM.

PURPOSE: This investigation was undertaken to examine substrate utilization and glucose turnover during exercise of varying intensities in NIDDM patients. METHODS: Six male NIDDM patients (N) and six male controls (C) of similar age, body weight, % body fat, and VO2peak were studied in two experimental sessions administered in a randomized counterbalanced order. During each session the subjects cycled at a power output corresponding to 50% of VO2peak or 70% of VO2peak. Duration of exercise was adjusted so that energy expenditure (EE) was equal in both the 50% and 70% trials. Isotope infusion technique and indirect calorimetry were used to assess substrate utilization and glucose turnover during exercise. RESULTS: Rates of carbohydrate (CHO) and lipid oxidation increased (P < 0.05) during both the 50% and 70% trials. Rates of CHO oxidation were greater (P < 0.05) during the 70% than during the 50% trial. However, rates of lipid oxidation were similar in the two trials. No differences in rates of CHO and lipid oxidation were observed in N and C. Rates of hepatic glucose production (Ra) and plasma glucose utilization (Rd) increased (P < 0.05) during exercise, and the increases were similar in the 50% and 70% trials. Ra did not differ between N and C. However, Rd was greater (P < 0.05) in N than in C. Plasma glucose concentration decreased (P < 0.05) in N, with the decrease being similar in the 50% and 70% trials. In contrast, plasma glucose concentration remained unchanged during both the 50% and 70% trials in C. CONCLUSIONS: Exercise results in a greater increase in plasma glucose utilization in patients with NIDDM compared with that in normal individuals, and this increase mediates the decline in plasma glucose concentrations in patients with NIDDM. Under isocaloric conditions, the changes in plasma glucose utilization and plasma glucose concentrations are similar during exercise of varying intensities. Despite a greater glucose utilization, carbohydrate and fat oxidation are similar in the two groups and their relations to exercise intensity are not altered by NIDDM.