Optimizing fat oxidation through exercise in severely obese Caucasian adolescents

OBJECTIVE: To measure the contribution of substrate oxidation to energy expenditure during cycling at different workloads and to identify the exercise intensity that elicits the maximum fat oxidation rate in groups of severely obese or nonobese Caucasian adolescents. DESIGN: A total of 30 severely obese subjects (mean body mass index, BMI = 34.7 kg/m2; fat-mass = 39.9%) and 30 nonobese sedentary adolescents (mean BMI = 22.7 kg/m2; fat-mass = 21.8%) aged 14-16 years, participated in this study. Body composition was assessed by bioelectrical impedance. Peak oxygen uptake (VO2peak) and maximal fat oxidation rate were determined with indirect calorimetry by using a graded exercise test on an electromagnetically braked cycle ergometer. RESULTS: Predicted VO2max were expressed in absolute (l/min) and relative (ml/kg FFM/min) values, and maximal work rates were not significantly different between obese and nonobese adolescents, but were significantly higher in boys than in girls. No significant differences in fat oxidation rates were found in obese and nonobese sedentary adolescents during the graded exercise test. Maximal fat oxidation was observed at an exercise intensity corresponding to (mean +/- SD) 41 +/- 3%VO2max or 58 +/- 3% HRmax. At this exercise intensity, fat oxidation rates were higher in boys than in girls (0.32 +/- 0.02 g/min vs. 0.25 +/- 0.02 g/min, P < 0.001). CONCLUSIONS: Severely obese and sedentary nonobese adolescents reached maximal fat oxidation rates at 41%VO2max, which corresponds to 58% HRmax. At this exercise intensity, fat oxidation rates were higher in boys than in girls probably due to higher VO2max and absolute workload during the exercise steps for boys compared with those for girls.     

Growth hormone replacement therapy in adults with growth hormone deficiency improves maximal oxygen consumption independently of dosing regimen or physical activity

CONTEXT: Several studies have demonstrated an improvement in aerobic exercise capacity with 6 months of GH replacement in adults with GH deficiency (GHD). OBJECTIVE: The objective of the study was to determine whether improvements in aerobic exercise capacity with GH treatment in adults with GHD are related to changes in physical activity or affected by the GH dosing regimen. DESIGN: This was a randomized, two-arm, parallel, open-label study. SETTING: The study was conducted at five academic medical centers with exercise physiology laboratories. SUBJECTS: Study subjects were adults (n = 29) with GHD due to hypothalamic-pituitary disease. INTERVENTIONS: The intervention was GH replacement therapy, administered either as a fixed body weight-based dosing regimen as an individualized dose titration regimen for 32 wk. MAIN OUTCOME MEASURES: Maximal oxygen consumption (VO2 max) and oxygen consumption (VO2) at the lactate threshold, ventilatory threshold using a cycle ergometry protocol, and weekly energy expenditure (physical activity questionnaire), assessed at baseline and end point, were measured. RESULTS: In the group as a whole, VO2 max increased significantly (by 9%) from baseline (19.1+/- 0.89 ml/kg.min) to end point (21.6 +/- 1.23 ml/kg.min, P = 0.010). Compared with baseline, VO2 max also changed significantly within the individualized dose titration regimen group (+2.5 +/- 0.98 ml/kg.min, P =0.034) but not within the fixed body weight-based dosing regimen group (+1.2 +/- 0.78 ml/kg.min, P = 0.15), although these changes from baseline were not significantly different between the two groups. VO2 at lactate threshold, VO2 at ventilatory threshold, and weekly energy expenditure also did not change. CONCLUSIONS: GH replacement therapy in GH-deficient adults improved VO2 max similarly with both dosing regimens, without any influence of physical activity. There was no effect on submaximal exercise performance.     

Substrate oxidation differences between high- and low-intensity exercise are compensated over 24 hours in obese men

OBJECTIVE: Exercise has been proposed as a tool for the prevention of obesity. Apart from an effect on energy expenditure, in particular low-intensity (LI) exercise might also influence substrate metabolism in favour of fat oxidation. It is however unclear what is the most beneficial exercise regime for obese people. We therefore studied the effect of either high-intensity (HI) or LI exercise on 24 h energy expenditure (24 h EE) and substrate metabolism. METHODS: Eight healthy obese male volunteers (age: 38+/-1 y, BMI: 31+/-1 kg/m(2), W(max): 235+/-16 W) stayed in the respiration chamber for two nights and the day in-between. In the chamber they cycled either at a HI (three times 30 min in a interval protocol (2.5 min 80/50% W(max))) or LI (three times 60 min continuously at 38% W(max)) protocol with an equicaloric energy expenditure. In the chamber subjects were fed in energy balance (37/48/15% of energy as fat/carbohydrate/protein). RESULTS: The 24 h EE was not significantly different between protocols. In both protocols, sleeping metabolic rate (SMR) was elevated after the exercise (average+6.7%). The 24 h respiratory quotient (24 h RQ) was not different between protocols. During exercise, RQ was higher in the HI compared to the LI protocol (0.93 vs 0.91 resp., P<0.05), whereas in the postexercise period RQ tended to be lower in the HI compared to the LI protocol (P=0.06). CONCLUSION: 24 h EE is not differently affected by HI or LI exercise in obese men. Similarly, the differences in HI and LI exercise, RQ are compensated postexercise leading to similar substrate oxidation patterns over 24 h independently of the level of exercise intensity.     

Reduced mechanical efficiency in chronic obstructive pulmonary disease but normal peak VO2 with small muscle mass exercise

We studied six patients with chronic obstructive pulmonary disease (COPD) (FEV1 = 1.1 +/- 0.2 L, 32% of predicted) and six age- and activity level-matched control subjects while performing both maximal bicycle exercise and single leg knee-extensor exercise. Arterial and femoral venous blood sampling, thermodilution blood flow measurements, and needle biopsies allowed the assessment of muscle oxygen supply, utilization, and structure. Maximal work rates and single leg VO2max (control subjects = 0.63 +/- 0.1; patients with COPD = 0.37 +/- 0.1 L/minute) were significantly greater in the control group during bicycle exercise. During knee-extensor exercise this difference in VO2max disappeared, whereas maximal work capacity was reduced (flywheel resistance: control subjects = 923 +/- 198; patients with COPD = 612 +/- 81 g) revealing a significantly reduced mechanical efficiency (work per unit oxygen consumed) with COPD. The patients had an elevated number of less efficient type II muscle fibers, whereas muscle fiber cross-sectional areas, capillarity, and mitochondrial volume density were not different between the groups. Therefore, although metabolic capacity per se is unchanged, fiber type differences associated with COPD may account for the reduced muscular mechanical efficiency that becomes clearly apparent during knee-extensor exercise, when muscle function is no longer overshadowed by the decrement in lung function.     

Impact of the v/v 55 polymorphism of the uncoupling protein 2 gene on 24-h energy expenditure and substrate oxidation

OBJECTIVE: The gene that codes for a novel uncoupling protein, UCP2, has been linked to obesity in animal models. Markers encompassing the UCP2 locus have been linked to energy expenditure in humans. We studied the role of a common amino acid substitution, replacing an alanine (A) with a valine (V) at codon 55, of the coding region of the UCP2 gene for 24-h energy expenditure and respiratory quotient (RQ) in healthy subjects METHODS:24-h energy expenditure and RQ were measured in calorimeters in 60 healthy subjects. The UCP2 polymorphism was determined by restriction fragment length polymorphism-generating polymerase chain reaction. RESULTS: Age, gender and body fat were not different between groups, the number of subjects in each groups was A/A: 35% (n=21), A/V: 48% (n=29), and V/V: 17% (n=10). Twenty-four-hour energy expenditure, adjusted for fat-free mass, fat mass, and spontaneous physical activity, was 311 kJ/d lower (95% confidence interval: 24-598 kJ/d, P=0.03) in the V/V homozygotes than in the A/A and A/V genotypes. The V/V had approximately 20% higher 24-h spontaneous physical activity, particularly higher at night (P<0.005). Energy expenditure due to higher spontaneous physical activity counteracted the V/V group's lower 24-h resting energy expenditure for a given body size and composition. 24-h RQ adjusted for energy balance, age, sex and spontaneous physical activity, was higher in the V/V homozygotes than in the AA and A /V groups (P<0.05). CONCLUSIONS: Subjects with the V/V genotype of the UCP2 gene exhibit an enhanced metabolic efficiency and lower fat oxidation than the A/A and A/V genotypes.     

Altered adaptive responses to training by nonselective beta-adrenergic blockade in coronary artery disease

To examine the alterations in adaptive responses to training by nonselective beta-adrenergic blockade in patients with coronary artery disease (CAD), 26 patients were studied. Thirteen patients, aged 48 +/- 2 years (mean +/- standard error) were treated with beta-adrenergic blocking agents and another 13, aged 55 +/- 2 years, were control subjects. The 2 groups were similar in terms of initial maximal attainable O2 consumption (VO2max): 24 +/- 1 vs 25 +/- 2 ml/kg/min, patients and control subjects, respectively), and intensity (87 +/- 3.0 vs 88 +/- 2% of attainable VO2max), frequency (4 +/- 0.2 vs 4.0 +/- 0.3 days/week), and duration (12 months) of training. Maximal attainable VO2 increased to the same extent (36% vs 35%) in both groups. Heart rate (HR) at rest decreased to a similar extent in both groups (p less than 0.001). During submaximal exercise at the same exercise intensities, HR decreased in both groups, but to a larger extent in the control group than in the beta-blocker group after training. In the later, the reduced HR during submaximal exercise was solely due to training-induced bradycardia at rest. In contrast, the slower HR during submaximal exercise in control subjects after training was attributable to both bradycardia at rest and a smaller increase in HR during submaximal exercise. In both groups, the half-time of HR deceleration after cessation of exercise decreased (p less than 0.005) after training. However, the training-induced decrease in the half-time was significantly larger (p less than 0.025) in control subjects than in patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of exercise capacity with cardiopulmonary exercise testing and type B natriuretic peptide concentrations in adult patients with patent atrial septal defect

Adults with patent atrial septal defect (ASD) usually find their exercise capacity satisfactory, and therefore hesitate to accept proposed surgical treatment of the heart disease. The aim of our study was to evaluate both the exercise capacity, using the cardio-pulmonary stress test, and brain natriuretic peptide (BNP) levels in asymptomatic adults with ASD. Thirty-six patients with patent secundum type ASD (aged mean 44.7 +/- 8.2 years) were studied. The control group consisted of 25 healthy subjects at the mean age of 45.6 +/- 6.1 years. Echocardiography and CPST were performed and BNP levels measured in all subjects. Oxygen uptake (VO2 max) was lower in ASD patients than in controls (22.1 +/- 5.6 vs. 30.0 +/- 6.8 ml/kg/min, p = 0.00001); the VE/VO2 slope was elevated in ASD patients compared with healthy subjects (31.3 +/- 6.6 vs. 26.9 +/- 3.3, p = 0.001), and exceeded 34 in 5 patients. VO2 max showed a negative correlation with the pulmonary to systemic flow ratio Qp:Qs (r = -0.46, p = 0.004), and a positive correlation was found between the VE/VO2 slope and Qp:Qs (r = 0.32, p = 0.05). BNP levels were higher in the ASD group than in the controls (60.6 +/- 49.9 vs. 32.6 +/- 24.5 pg/ml, p = 0.02). BNP correlated positively with RV diameter and Qp:Qs (r = 0.38 and 0.39 respectively, p = 0.03) and negatively with maximum VO2 (r = -0.5, p = 0.004) and VO2% (r = -0.32, p = 0.07). CONCLUSIONS: Although most adult patients with ASD perceive their exercise capacity as satisfactory, objective assessment reveals that in fact it is significantly decreased. BNP levels are increased comparing to healthy individuals. Decreased exercise capacity and increased BNP levels seem to result from right ventricular volume overload.     

Cardiopulmonary exercise test for evaluating cardiac reserve in chronic congestive heart failure]

To evaluate whether maximal oxygen consumption (VO2 max) measured by cardiopulmonary exercise test (CAR-PET) reflects cardiac reserve in patients with congestive heart failure (CHF), supine bicycle CAR-PET and exercise hemodynamic measurements were performed simultaneously in 12 patients with CHF of NYHA II-IV. With increasing workload, VO2 and cardiac output elevated gradually, then plateaued, demonstrating that patients with CHF could reach VO2max. According to VO2max, patients were divided into 4 classes: including 2 patients of class A (VO2max: 24.5 +/- 2.29 ml.min-1/kg, mean +/- s mean), 3 of B (17.6 +/- 1.37 ml.min-1/kg), 5 of C (13.6 +/- 0.66 ml.min-1/kg) and 2 of D (6.5 +/- 1.64 ml.min-1/kg). Maximal cardiac indices were 8.79 +/- 2.35 L.min-1/m2 in class A, 5.82 +/- 0.97 L.min-1/m2 in B, 3.53 +/- 0.95 L.min-1/m2 in C and 2.21 +/- 1.56 L.min-1/m2 in D. No significant correlation between supine resting hemodynamic parameters and VO2max/kg was found, suggesting that exercise tolerance could not be predicted by the measurement of resting cardiac performance. Furthermore, VO2max correlated poorly with NYHA classification in these patients. However, cardiac output correlated linearly with VO2 during exercise, suggesting that VO2 max/kg is a good predictor for cardiac reserve in CHF(CI = 0.6809 +/- 0.2748 VO2/kg, n = 40, r = 0.84, P < 0.0001; CO = 1.1618 +/- 7.9065 VO2, n = 40, r = 0.84, P < 0.0001). The results also showed that VO2max/kg did not correlate with the changes of pulmonary capillary wedge pressure (PCWP), indicating that exercise tolerance in CHF depends more on cardiac output than on ventilatory consequence of pulmonary congestion.(ABSTRACT TRUNCATED AT 250 WORDS)     

The common -55 C/T polymorphism in the promoter region of the uncoupling protein 3 gene reduces prevalence of obesity and elevates serum high-density lipoprotein cholesterol levels in the general Japanese population

Uncoupling protein 3 (UCP3) is considered to be associated with obesity, given its function in the regulation of energy and lipid metabolism. An increased body mass index (BMI) and a decreased level of high-density lipoprotein cholesterol (HDL-C) are risk factors for cardiovascular disease. The purpose of this study was to investigate whether the UCP3 promoter -55 C/T single nucleotide polymorphism (UCP3 -55 C/T SNP) was associated with obesity according to the criteria for Japanese (BMI > or = 25 kg/m2), BMI, and serum HDL-C levels in the general Japanese population. The subjects, numbering 282 and aged 65 +/- 13 years (mean +/- SD), were recruited through an annual health checkup of residents of Mima city, Tokushima, in Japan. Body mass index, blood pressure, biochemical indexes including lipid, and lipoprotein profiles were measured. The UCP3 -55 C/T SNP was determined with a fluorescence-based allele-specific DNA primer assay system. The frequency of the -55 T allele was 30.0%. Subjects with the T/T genotype had significantly higher HDL-C levels than those with the C/C genotype or the C/T genotype. Furthermore, subjects with the T/T genotype had a significantly lower BMI than those with the C/C genotype. A multivariate analysis revealed that the -55 T allele was a significant independent variable contributing to the variance in HDL-C levels and BMI. The T/T genotype was associated with a lower prevalence of obesity than the C/C and C/T genotypes, with an odds ratio of 0.358 (95% confidence interval, 0.132-0.972; P = .037). In conclusion, the UCP3 -55 C/T SNP was associated with elevated HDL-C levels and a reduced BMI, independent of modifiable factors such as lifestyle. Furthermore, this polymorphism, when expressed in its homozygous form, reduced the prevalence of obesity in Japanese.     

Comparison of cardiovascular adjustments to exercise in adolescents 8 to 15 years of age after correction of tetralogy of fallot, ventricular septal defect or atrial septal defect

Surgical correction of tetralogy of Fallot (TF) has generally been associated with a reduced maximal exercise tolerance, possibly related to the ventriculotomy inherent to the intracardiac repair procedure. This study documents the exercise hemodynamics of a group of patients operated on for TF who showed similar clinical and functional characteristics, and compares these responses to those of age-matched patients operated on for an isolated ventricular septal defect (VSD) or atrial septal defect (ASD) in an attempt to better understand the role of the ventriculotomy in the exercise limitation. Thirty patients, ages 12 to 19 years, operated on before 5 years of age for complete repair of TF (n = 13), VSD (n = 7) or ASD (n = 10) and 10 age-matched control subjects underwent a progressive maximal cycling test to determine the maximal oxygen uptake (VO2 max), and completed submaximal cycling at intensities of 33 and 66% VO2 max, respectively, to determine the cardiac output (CO2-rebreathing). No significant differences in VO2 max were observed (TF = 37.6 +/- 10; VDS = 34.0 +/- 9.2; ASD = 36.5 +/- 7; controls = 41.3 +/- 6.0 ml/kg/min). The maximal heart rate, however, remained lower in all patient groups in comparison with control subjects (p less than or equal to 0.05) (TF = 178 +/- 14; VSD = 172 +/- 17; ASD = 179 +/- 16; controls = 191 +/- 12 beats/min).(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of usefulness between exercise capacity and echocardiographic indexes of left ventricular function in cardiac amyloidosis

In patients with primary systemic amyloidosis (AL), the echocardiographic assessment of ventricular function alone does not always correspond to patients' symptoms and functional status. Peak oxygen uptake and anaerobic threshold (AT), in contrast, constitute 2 objective, reliable and reproducible indicators of functional status in patients with circulatory failure. Thirty-two consecutive patients (mean age 50 +/- 13 years) with histologic evidence of systemic primary AL were studied (29 AL, 3 hereditary). There were 16 with echocardiographic features of cardiac infiltration (group I) and 16 without (group II). Twenty age- and gender-matched healthy subjects were also studied for comparison. Of the 32 patients, 12 were in New York Heart Association functional class I, 9 were in class II, and 11 were in class III. Each subject underwent 2-dimensional and Doppler echocardiography and cardiopulmonary exercise testing using a modified Bruce protocol. Left atrial (LA), left ventricular (LV) dimensions, wall thickness, and LV fractional shortening, as well as transmitral flow velocities and their E/A ratio were measured. Peak oxygen consumption (VO2max [ml/kg/min]), AT (ml/kg/min), and exercise duration (seconds) were also measured. VO2max and AT were lower in patients with AL than in controls (20.8 +/- 7.0 vs 35.0 +/- 8.5, p <0.001 and 13.1 +/- 3.7 vs 27.0 +/- 4.2, p <0.001, respectively). As a group, symptomatic patients had lower VO2max, AT, and exercise duration than those without symptoms (17.1 +/- 3.6 vs 27.0 +/- 6.9, p = 0.0001, 11.1 +/- 2.1 vs 16.2 +/- 3.6, p = 0.0001, and 489 +/- 235 vs 843 +/- 197, p = 0.0001, respectively), whereas LV dimensions only showed a small difference (p = 0.03). VO2max, AT, and exercise duration of patients in functional class I were higher than those in functional classes II and III (p = 0.01, p <0.05, and p = 0.007, respectively). Asymptomatic patients had lower VO2max, AT, and exercise duration than controls (p <0.0001). VO2max, AT, and exercise duration were poorly related to LA diameter, LV dimensions, fractional shortening, wall thickness, peak velocities of E and A waveforms, and E/A ratio. Patients with VO2max > 15 ml/kg/min had a better survival than patients with VO2max < 15 ml/kg/min. Thus, in patients with primary systemic AL, cardiorespiratory exercise testing is the preferred way of assessing functional capacity. Echocardiographic Doppler indexes at rest are not predictive of a patient's symptoms and exercise capacity. Furthermore, VO2max is a strong independent predictor of survival in these patients.     

Total energy expenditure and energy requirements in healthy elderly persons.

To investigate energy requirements in healthy elderly subjects, we assessed the association of total energy expenditure (TEE) with resting metabolic rate (RMR), physical activity, body composition, and energy intake in 13 individuals (aged 56 to 78 years, six women and seven men). Free-living TEE was measured using doubly labeled water, RMR was measured by respiratory gas analysis, and energy expenditure of physical activity (EEPA) was derived from the difference between TEE and RMR, assuming the thermic response to feeding contributes 10% of TEE. Fat mass (FM) and fat-free mass (FFM) were obtained from underwater weighing, VO2max was determined from a bicycle test to exhaustion, energy intake was obtained from a 3-day food diary, and leisure time activity (LTA) was determined by structured interview. TEE was 2,406 +/- 438 kcal/d (range, 1,856 to 3,200 kcal/d, or 1.25 to 2.11 times RMR) and was related to VO2max (r = .79, P = .001), LTA (r = .74, P = .004), FFM (r = .69, P = .009), and FM (r = -.64, P = .018). The association between TEE and VO2max persisted after adjustment for FFM (partial r = .58, P = .036). EEPA was related to LTA (r = .83, P less than .0001) and FM (r = -.58, P = .039). Energy intake underestimated TEE by 31% +/- 18% in women and by 12% +/- 11% in men. Using stepwise regression, TEE was best predicted by VO2max and LTA (total adjusted r2 = .86). We conclude the following: (1) TEE varies greatly within healthy elderly subjects due to variations in physical activity; (2) VO2max has an important role in predicting energy requirements in older individuals; and (3) healthy older individuals underreport energy intake.     

Nifedipine and the conditioning response

The effect of nifedipine (N) on conditioning was studied in 14 healthy sedentary men, aged 20 to 34 years. Subjects were ranked according to maximal oxygen consumption (VO2 max), paired, and 1 of each pair randomly assigned to take N, 20 mg, or placebo (C) 3 times daily. Exercise conditioning was 5 times/week for 6 weeks at greater than 85% of maximal heart rate for both groups. Adherence to exercise was 81% for the N and 82% for the C group. After training, the N group improved VO2 max from 41.4 +/- 1.4 to 51.6 +/- 2.0 ml/kg/min (p less than 0.05) and exercise time from 22 +/- 1 to 28 +/- 1 minutes (p less than 0.05). Heart rate (HR) at rest and the product of heart rate and systolic blood pressure both decreased (p less than 0.05): 70 +/- 6 to 55 +/- 4 beats/min; 9,300 +/- 900 to 6,800 +/- 700 beats/min X mm Hg. In the C group, VO2 max increased from 43.2 +/- 2.5 to 49.9 +/- 2.5 ml/kg/min (p less than 0.05); exercise duration improved from 24 +/- 2 to 29 +/- 2 minutes (p less than 0.05), and the rate-pressure product at rest decreased from 8,000 +/- 400 to 6,700 +/- 400 (p less than 0.05). Differences between N and C were not significant. Thus, N, unlike propranolol, does not inhibit the response to exercise conditioning.     

The incremental benefit of rate-adaptive pacing on exercise performance during cardiac resynchronization therapy.

OBJECTIVES: The purpose of this research was to investigate the effect of using rate-adaptive pacing and atrioventricular interval (AVI) adaptation on exercise performance during cardiac resynchronization therapy (CRT). BACKGROUND: The potential incremental benefits of using rate-adaptive pacing and AVI adaptation with CRT during exercise have not been studied. METHODS: We studied 20 patients with heart failure, chronotropic incompetence (<85% age-predicted heart rate [AP-HR] and <80% HR reserve), and implanted with CRT. All patients underwent a cardiopulmonary exercise treadmill test using DDD mode with fixed AVI (DDD-OFF), DDD mode with adaptive AVI on (DDD-ON), and DDDR mode with adaptive AVI on (DDDR-ON) to measure metabolic equivalents (METs) and peak oxygen consumption (VO2max). RESULTS: During DDD-OFF mode, not all patients reached 85% AP-HR during exercise, and 55% of patients had <70% AP-HR. Compared to patients with >70% AP-HR, patients with <70% AP-HR had significantly lower baseline HR (66 +/- 3 beats/min vs. 80 +/- 5 beats/min, p = 0.015) and percentage HR reserve (27 +/- 5% vs. 48 +/- 6%, p = 0.006). In patients with <70% AP-HR, DDDR-ON mode increased peak exercise HR, exercise time, METs, and VO2max compared with DDD-OFF and DDD-ON modes (p < 0.05), without a significant difference between DDD-OFF and DDD-ON modes. In contrast, there were no significant differences in peak exercise HR, exercise time, METs, and VO2max among the three pacing modes in patients with >70% AP-HR. The percentage HR changes during exercise positively correlated with exercise time (r = 0.67, p < 0.001), METs (r = 0.56, p < 0.001), and VO2max (r = 0.55, p < 0.001). CONCLUSIONS: In heart failure patients with severe chronotropic incompetence as defined by failure to achieve >70% AP-HR, appropriate use of rate-adaptive pacing with CRT provides incremental benefit on exercise capacity during exercise.     

Behavioral and physiological regulation of body fatness: a cross-sectional study in elderly men

OBJECTIVE: To identify the characteristics of physical activity that are the most correlated to total and truncal fatness and to physiological parameters involved in fat oxidation in elderly men. DESIGN: Cross-sectional study. SUBJECTS: A total of 25 healthy elderly men selected with a wide range of physical activity behavior (65.9 +/- 3.4 years).Measurements:Total and truncal fat masses (by dual-energy X-ray absorptiometry), time spent and energy expended (EE(day)) at specific activity intensities (<40, 40-60, >60% VO2max) during 1 week in free living conditions (using heart rate recording and individual calibrated equations), sport-exercising volume (V(sport), using Baecke questionnaire), maximal oxygen uptake (VO2max), muscle fat oxidative capacity (OX(FA), using muscle biopsy), lipid oxidation and respiratory exchange ratio during exercise at 50% VO2max (using indirect calorimetry). RESULTS: V(sport) was the main determinant of total and truncal fatness, VO2max and OX(FA) (r = -0.69, P < 0.0001; r = -0.80, P < 0.0001; r = 0.70, P < 0.0001; r = 0.66, P<0.001, respectively). Among physical activity parameters measured over a week, total EE(day) was the main determinant of total fat mass. Furthermore, EE(day) at % VO2max > 60 was closely correlated to truncal fat mass, VO2max and OX(FA) (r = -0.58, P > 0.01; r = 0.55, P < 0.01; r = 0.49, P < 0.05, respectively). Finally, VO2max and OX(FA) were positively correlated to absolute fat oxidation and to the contribution of fat to energy production during moderate exercise. CONCLUSION: Sport-exercising volume is the main factor regulating total and truncal fat masses and physiological parameters involved in fat oxidation. With regard to the characteristics of physical activity, overall energy expended during the alert period plays a major role in the regulation of total body fatness. In addition, vigorous exercises may be beneficial for the regulation of abdominal fat depot partly through the stimulation of muscle fat oxidation during the effort.     

Pulmonary function and exercise tolerance in patients treated with bone marrow transplantation (BMT)]

We assessed pulmonary function and exercise tolerance in 10 BMT patients. Their underlying disorders were as follows; chronic myeloid leukemia 5 cases, acute lymphoblastic leukemia 2 cases, aplastic anemia, acute myeloid leukemia and non-Hodgkin's lymphoma one case each. Their mean age was 26 +/- 9 years old. When the patients were healthy and free of serious complications and anemia, arterial blood gas examination, pulmonary function tests and incremental treadmill exercise test were examined repeatedly. Although %VC and FEV1.0% kept within normal range, PaO2 at rest, %DLCO, VO2max, VO2max/kg and O2-pulsemax remained low at one year after BMT. There were significant correlations between VO2max and O2-pulsemax [r = 0.955 (p < 0.001)], %VC [r = 0.758 (p < 0.02)], VE/VO2max [r = -0.749 (p < 0.02)] and delta SaO2/VO2/kg [r = -0.731 (p < 0.02)], suggesting that exercise intolerance in BMT patients may be based on both cardiac and gas exchange abnormalities. To evaluate cardiac dysfunction, we compared exercise parameters obtained at an exercise level of 75% predicted heart rate max in five age-matched normal subjects to those in six BMT patients who did not demonstrate desaturation during exercise. As a result, the mean values of VO2max/kg and O2-pulse/m2 in BMT patients were significantly lower than those in normal subjects, suggesting that cardiac dysfunction may be due to insufficiency of stroke volume during exercise. It is concluded that exercise intolerance in BMT patients may be mainly due to cardiac dysfunction.     

Prediction of maximal oxygen uptake and power during cycle ergometry in subjects older than 55 years of age

One hundred twenty-eight healthy volunteers (81 women, 47 men) older than 55 yr of age were studied with an incremental progressive cycle ergometer test to a symptom-limited, maximal tolerable work load. Mean (+/- SD) age was 66 +/- 6 yr in women and 66 +/- 5 years in men. Subjects with a history of ischemic heart disease, diabetes, pulmonary disease, or neuromuscular disease were excluded. Smokers were included, but all subjects had normal FEV1 and FVC. The objective of the study was to compare measured values of VO2max and Wmax in this older population with previously published predicted values based on subjects of all ages. We found that Wmax observed exceeded Wmax predicted by 9.5 +/- 22% (mean +/- SD) and that VO2max observed exceeded VO2max predicted by 17.5 +/- 22%. Because of this systematic underestimate of VO2max and Wmax by the previous prediction equations, we constructed new prediction equations for use in subjects older than 55 yr of age using height, weight, age, and sex as variables. We conclude that these new prediction equations more accurately predict Wmax and VO2max in subjects older than 55 yr of age because they are based solely on subjects in this age group.     

Alcohol and postexercise metabolic responses in type 2 diabetes.

The objective was to investigate the impact of the combination of exercise and alcohol on the metabolic response in nonfasting and fasting type 2 diabetic subjects. In part 1, 12 untrained middle-aged type 2 diabetic subjects participated on 3 test days. On each day, they ingested a light meal (1,824 kJ) containing 48 energy percent (E%) carbohydrate, 38 E% fat, and 14 E% protein. The meal was followed by either (A) rest or (B) 30 minutes of exercise (40% of maximum O2 consumption [VO2max]) or (C) taken with alcohol (0.4 g/kg body weight) followed by 30 minutes of exercise (40% of VO2max). In part 2, 11 untrained middle-aged type 2 diabetic subjects participated on 4 test days without a meal. The subjects were either (A) resting, (B) drinking alcohol (0.4 g/kg body weight), (C) exercising 30 minutes (40% of VO2max), or (D) drinking alcohol (0.4 g/kg body weight) and exercising 30 minutes (40% of VO2max). On each test day, regular blood samples were drawn for 4 hours for analysis of glucose, insulin, lactate, triglycerides, nonesterified fatty acid (NEFA), and ethanol. Comparing exercise and rest following a light meal (part 1, no change (7%) occurred in the plasma glucose response area (642 +/- 119 v 724 +/- 109 mmol x L(-1) x 240 min, NS). However, it was significantly reduced (by 27%) in response to exercise and alcohol (509 +/- 98 v 724 +/- 109 mmol x L(-1) x 240 min; P = .03). Similar serum insulin response areas were obtained. After exercise and alcohol, plasma lactate increased compared with the resting state (2.2 +/- 0.2 v 1.6 +/- 0.1 mmol x L(-1), P = .004) and with exercise alone (2.2 +/- 0.2 v 1.8 +/- 0.2 mmol x L(-1), P = .04). Serum NEFAs were significantly reduced by exercise and alcohol compared with the resting state (0.50 +/- 0.04 v 0.65 +/- 0.06 mmol x L(-1), P = .008) and with exercise alone (0.50 +/- 0.04 v 0.61 +/- 0.05 mmol x L(-1), P = .02). Similar serum triglycerides were found. During the fasting state (part 2), similar plasma glucose response areas were obtained in the four situations. The insulin response area to exercise and alcohol increased significantly compared with the resting state (3,325 +/- 744 v 882 +/- 295 pmol x L(-1) x 240 min, P = .02) and with exercise alone (3,325 +/- 744 v 1,328 +/- 422 pmol x L(-1) x 240 min, P = .007). No difference was found compared with alcohol alone. Plasma lactate was higher after alcohol intake versus the resting state (1.9 +/- 0.1 v 1.3 +/- 0.1 mmol x L(-1), P = .003), as well as after exercise and alcohol (1.9 +/- 0.1 v 1.3 +/- 0.1 mmol x L(-1), P = .01). After exercise and alcohol serum NEFAs were significantly reduced compared with the resting state (0.43 +/- 0.02 v 0.64 +/- 0.02 mmol x L(-1), P < .001), alcohol alone (0.43 +/- 0.02 v 0.51 +/- 0.02 mmol x L(-1), P < .001), and exercise alone (0.43 +/- 0.02 v 0.64 +/- 0.02 mmol x L(-1), P < .001). Serum triglycerides were similar in the four situations. We conclude that moderate exercise with or without moderate alcohol intake does not cause acute hypoglycemia either after a light meal or in the fasting state in untrained overweight type 2 diabetic subjects.