Assessment of respiratory compensation phase during graded exercise in patients with chronic heart failure

BACKGROUND: The VE-VO2 relationship during graded exercise has an inflection point beyond the ventilatory anaerobic threshold (VAT) termed the respiratory compensation point (RCP). Metabolic variables analyzed at the level of VAT and RCP may contribute to the better understanding of such limiting symptoms in chronic heart failure (CHF) patients as dyspnea and early fatigue. The AIM of the present study was to analyze the RCP during symptom limited ramp exercise testing in CHF patients. PATIENTS AND METHODS: Forty six CHF patients (II and III NYHA functional class; age = 51 +/- 9 years, LVEF% = 35% +/- 6%; mean +/- SD) and 20 matched controls performed graded cardiopulmonary exercise test on a cycle ergometer. RESULTS: The duration and productivity of RCP (delta(x) = peak(x) - VAT(x)) in patients were significantly (p < 0.001) reduced compared to healthy subjects: delta duration = 3.0 +/- 1.2 vs 4.3 +/- 1.5 min, delta watts = 24.3 +/- 11.5 vs. 39.4 +/- 11.5, delta VO2/kg (ml.kg-1 x min-1) = 3.8 +/- 1.3 vs 8.8 +/- 2.3. An important characteristic of this phase was the higher subjective cost of physical effort assessed by Borg scale and Watts/Borg ratio (Borg peak = 9.9 +/- 0.4 vs. 6.0 +/- 1.2; p < 0.001, Watts/Borg peak = 9.2 +/- 2.3 vs 23.9 +/- 6.4, p < 0.001). The relative hyperventilation of patients on the basis of the watt exercise can be seen in the values of derivative index V (ml x min-1 x watt-1) 478 +/- 59 vs 568 +/- 118; (p < 0.001) in controls and patients, respectively. CONCLUSIONS: The impaired efficiency of oxygen delivery systems in patients with CHF is what causes the appearance of early limiting symptoms. Duration and productivity of respiratory compensation phase in CHF patients are considerably reduced compared to controls.     

Effects of short-term exercise training in patients with heart failure.

Heart failure is a debilitating disorder which limits exercise capacity and produces a poor quality of life. The present study was designed to determine the effects of an exercise training program on patients with CHF NYHA functional class II-III, attributed to left ventricular systolic dysfunction and dilated left ventricle. Twenty-two ambulatory male patients with stable CHF were randomised to a training (n = 15) and a control group (n = 7). A symptom limited ramp cardiopulmonary exercise test with gas exchange analysis was performed at baseline after 4 and 8 weeks. The training group underwent an exercise training program at 50% of peak oxygen uptake for eight weeks. The control group was not exercised. After 8 weeks, compared with baseline, there were statistically significant increase in peak oxygen uptake, peak workload, anaerobic threshold, oxygen pulse, RPP, ventilation and the duration of the test only in trained patients. The reduction in scores tested by the Minnesota Living with Heart Failure questionnaire (p < 0.001) and Borg dyspnea rating score (p < 0.001) reflect the reduction of symptoms and the improvement in health-related quality of life. Carefully selected patients with moderate to severe CHF can achieve significant improvements of exercise capacity and quality of life with exercise training and can safely participate in a conditioning program.     

Long-term changes in dyspnea, lung function, and exercise capacity in COPD patients

OBJECTIVE: To examine longitudinal changes in dyspnea, lung function, and exercise capacity in COPD patients and to compare baseline data of frequent and infrequent exacerbators at trial entry. METHODS: Nineteen stable COPD patients without significant co-morbidity (age, 58.4 +/- 8.4 years; FEV1% = 33 +/- 12%; mean +/- SD) participated in the study. After a mean period of 36 months (range = 24 - 49) the patients were retested using an identical protocol. RESULTS: Repeated measures analysis showed that there was significant deterioration of FEV1 L (from 1.028 +/- 0.349 to 0.928 +/- 0.307; p = 0.007), PImax cm H2O (from 61.9 +/- 24.2 to 42.0 +/- 22.1; p = 0.007), PaO2 mm Hg (from 69.0 +/- 8.6 to 60.1 +/- 6.8; p = 0.003), PaCO2 mm Hg (from 43.1 +/- 4.9 to 47.3 +/- 4.5; p = 0.001), ATS (from 2.4 +/- 1.0 to 2.8 +/- 0.8; p = 0.031), and 6MWD m (from 389 +/- 130 to 341 +/- 135; p = 0.014). There were also changes in IC, T(L,CO)/V(A), PAP and Borg, but they were not statistically significant. Differentiation of patients by frequency of exacerbations per year of observation (> 2 < or =) discriminated them with respect to functional parameters (FEV1, FVC, IC), dyspneic indices (ATS, VAS and Borg) and exercise capacity (6MWD) at the time of enrollment. CONCLUSIONS: 1) Lung function parameters, blood-gas and dyspneic indices, and exercise capacity decline over a mean period of 36 month in patients with COPD; 2) Patients with frequent exacerbations experience more dyspnea and have lower levels of lung function and exercise capacity at trial entry.     

The effect of controlled and uncontrolled dynamic lower extremity training in the rehabilitation of patients with chronic obstructive pulmonary disease

Pulmonary rehabilitation has become a part of the integrated management of patients with chronic obstructive pulmonary disease (COPD). The lower extremity dynamic training has been proved to be the most effective element of the program. OBJECTIVE: Does the supervised training have more favorable effect in case of similar program? PATIENTS AND METHODS: In two groups: 54 patients, supervised (group K, n = 22) and not supervised (group NK, n = 32) by physiotherapists, chosen at random have been investigated. Both groups consisted of hospitalized patients of the same severity (forced expiratory volume in one second) [FEV1 (average +/- SD)]: K: 51.0 +/- 16.1 vs. NK: 51.9 +/- 15.6% pred). Group K performed physiotherapist-supervised cycling training in the Pulmonology Ambulance Unit 3-4 times a week for 45 minutes doing an 8-week period and group NK performed training in the form of cycling, stepping on stairs or dynamic walking at home with the same duration, weekly periodicity and time interval. RESULTS: After rehabilitation vital capacity (VC) (K: 3.0 +/- 0.8 vs. 3.3 +/- 0.7 l, p < 0.05), emphysema ratio (RV/TLC): K: 53.5 +/- 10.1 vs. 51.6 +/- 9.9, p < 0.05) in the supervised group, and alveolar volume (VA) in the not supervised group (NK: 4.3 +/- 0.9 vs. 4.7 +/- 0.9 l, p < 0.05) significantly improved. Improvement of exercise capacity was more effective in group K (K: 92.7 +/- 33.9 vs. 106.4 +/- 34.5 W, p < 0.001; NK: 95.8 +/- 36.7 vs. 99.9 +/- 35.1 W, p < 0.05). In both groups aerobic capacity (VO2: K: 1.2 +/- 0.4 vs. 1.3 +/- 0.4 l/min, p < 0.01, NK: 1.1 +/- 0.4 vs. 1.2 +/- 0.4 l/min, p < 0.01; VO2/kg: K: 16.1 +/- 5.5 vs. 17.5 +/- 5.8 ml/kg/mm, p < 0.01, NK: 16.2 +/- 5.3 vs. 16.7 +/- 4.8 ml/kg/ min, p < 0.01) and anaerobic threshold level [AT (pred VO2%)] (K: 36.6 +/- 9.8 vs. 42.8 +/- 10.2%, p < 0.001; NK: 40.8 +/- 12.0 vs. 44.6 + 11.6%, p < 0.001) significantly improved. Heart rate reserve: (K: 17.7 +/- 22.7 vs. 28.8 +/- 31.5 l/min, p < 0.01; NK: 20.4 +/- 21.2 vs. 25.0 +/- 21.6 l/min, p < 0.01) improved at the same level of exercise. The Borg scale of dyspnea (0-10): (K: 6.4 +/- 2.5 vs. 5.7 +/- 2.7, p < 0.05; NK: 7.5 +/- 1.8 vs. 6.9 +/- 2.2, p < 0.05) was reduced and quality of life score (0-24): K: 11.5 +/- 0.7 vs. 9.0 +/- 2.8, p < 0.005; NK: 11.6 +/- 2.3 vs. 7.0 +/- 1.9, p < 0.005) was improved. CONCLUSION: In both group dynamic lower extremity training caused improvement in exercise capacity. The favorable metabolic effect of training was shown by the change of anaerobic threshold resulting in less carbon dioxide production during analogous exercise. This reduction led to less ventilation reducing the work of breathing in supervised group. The more favorable adaptation taking place in the group supervised by physiotherapists might have resulted from the controlled higher intensity of the training.     

Alterations in physiological and perceptual variables during exhaustive endurance work while wearing a pressure-demand respirator

The purpose of this investigation was to describe the time course of changes in physiological and perceptual variables during exhaustive endurance work with and without an air-supplied, full-facepiece, pressure-demand respirator. Thirty-eight healthy subjects (24 to 51 years of age) volunteered for this study. Treadmill speed was set at 5.5 kph (3.4 mph) and elevation was set at a level calculated to elicit 70% of a previously determined maximal aerobic capacity (VO2max). Subjects continued at this rate to exhaustion. Despite a constant work rate, VO2 and %VO2max increased during exercise and were significantly greater with the respirator (34.4 +/- 1.1 mL/kg.min; 84% VO2max) than without the respirator (31.9 +/- 1.1 mL/kg.min; 76% VO2max) at the "final" measurement point prior to termination of exercise by each subject. The final values for ventilation volume (VE) also were significantly greater with the respirator (89.2 +/- 3.4 L/min) than without (73.4 +/- 3.7 L/min). At the conclusion of the endurance walk, dyspnea index (VE/MMV.25) remained well below maximal values (with = 58.6 +/- 2%; without = 44.6 +/- 2%; p less than 0.001). Also, at the final period, no significant differences occurred in the subjects' perceptual ratings of work of breathing, yet work performance time was significantly reduced (p less than 0.0001) from 69.1 +/- 4.4 min (without) to 55.6 +/- 3.8 min (with). A significantly greater swing in peak pressure (maximum pressure measured within the facepiece of respirator), however, from inspired (PPi) to expired (PPe) occurred with the respirator (13.42 cmH2O) than without the respirator (9.25 cmH2O).(ABSTRACT TRUNCATED AT 250 WORDS)     

Cardiovascular and dyspnea response to six-minute and shuttle walk tests in COPD patients

Previous studies focusing on the changes of heart rate, systolic blood pressure and dyspnea caused by the six-minute (6MWT) and shuttle walking distance tests (ISWT) have produced conflicting data. The present study aims at comparing the cardiovascular and dyspnea responses to 6MWT and ISWT in patients with chronic obstructive pulmonary disease (COPD). Twenty patients with clinically stable COPD (age, 56 +/- 9 yrs; BMI, 27.8 +/- 7.7 kg.m(-2); FEV1%pred, 42 +/- 19%; mean +/- Sx) performed three 6MWTs and two ISWTs using standardised protocols. The distances walked in the third 6MWT and second ISWT were 458 +/- 105 and 365 +/- 116 m, respectively. There was a significant correlation between the distances covered in the two tests (r = 0.87; p < 0.001). The 6MWT and ISWT showed similar correlation coefficients with the Baseline Dyspnea Index (r = 0.86; p < 0.001 and r = 0.76; p < 0.001), the Clinical Symptom Scale (r= -0.72; p < 0.001 and r= -0.55; p = 0.011), FEV1 L (r = 0.36; NS and r = 0.30; NS), PImax (r = 0.59; p < 0.008 and r = 0.60; p = 0.001) and the mean pulmonary artery pressure, Doppler echocardiography (r= -0.51; p < 0.029 and r = -0.51; p = 0.032). Although the response to ISWT tended to be greater, we found no statistically significant differences between the two tests in the changes of heart rate (HR), systolic blood pressure (SBP) and dyspnea (Borg) (deltaHR, 17.9 +/- 13.4 vs 23.8 +/- 15.4; deltaSBP, 7.7 +/- 14.6 vs 13.0 +/- 17.0 and deltaBorg, 1.7 +/- 1.1 vs 2.2 +/- 0.9; NS). CONCLUSION: The cardiovascular and dyspnea response caused by ISWT is greater (but statistically not significant) than that generated by 6MWT. The more limited the functional capacity of COPD patients the more similar the response generated by 6MWT and ISWT.     

Functional parameters in pulmonary bullous emphysema.

OBJECTIVE: 1. compare a large set of functional parameters in patients with bullous emphysema and patients with nonbullous emphysema. 2. To compare a chest radiographs (CHR) and a high resolution computed tomography (HRCT) in the clinical assessment of bullous emphysema. MATERIAL AND METHODS: The study population included 43 stable COPD patients (age = 59 +/- 9 years; pack/year (P/Y) = 39 +/- 19; ATS dyspnea score = 2.3 +/- 0.9; FEV1%pred. = 30 +/- = 10%; KCO%pred. = 49 +/- 16%; 6MWD (six minute walk distance) = 395 +/- 103 m; mean +/- SD). The patients were divided into two groups (patients with and without bullae) by a HRCT. In most of the cases the size of the bullae, measured by CT scan, was less than 15 mm. Twenty two CHRs were read independently by three experienced chest radiologists who had no knowledge of the CT scan data. RESULTS: Statistically significant differences were found between the groups with bullous (n = 19) and nonbullous (n = 24) emphysema in FEV1 (p < 0.001); VC (p = 0.001); BMI (p = 0.018); Borg after exercise (p = 0.021); FEV1/VC% (p = 0.025) and P/Y (p = 0.034). The sensitivity of chest radiographs compared with CT scan regarding the small bullae was very low: 27.7% in radiologist I, 12.3% in radiologist II, and 21.5% in radiologist III. CONCLUSIONS: 1. The patients with bullous emphysema have statistically significant lower lung function indices (FEV1, VC, FEV1/VC%) and BMI than those with nonbullous emphysema. 2. Patients with bullous emphysema have higher level of dyspnea score after 6MWD and higher pack-year smoking status than those with nonbullous emphysema. 3. For the clinical evaluation of emphysema the information derived from a standardised reading of the CXR is not as valuable as that derived from the CT scan.     

Leptin response to glucocorticoid occurs at physiological doses and is abolished by fasting

OBJECTIVE: To examine the effects of graded doses of hydrocortisone (HC) on leptin secretion, and determine the effect of fasting. RESEARCH METHODS AND PROCEDURES: This was a randomized, placebo-controlled, crossover study, with a 1-week "washout" period between interventions. Eight healthy subjects [age = 36 +/- 2.3 years (+/-SE), body mass index = 31.5 +/- 1.6 kg/m(2)] completed the dose-response study in which an intravenous infusion of saline (placebo) or HC (30 or 100 mg) was administered for 24 hours. Four healthy subjects (age = 35.2 +/- 3.0 years, body mass index = 27.1 +/- 2.1 kg/m(2)) completed the fasting study, which entailed continuous infusion of saline, HC (300 mg/24 hours) in the fed state, or HC (300 mg/24 hours) with total caloric deprivation for 24 hours. Blood sampling was performed every 1 to 2 hours for measurement of leptin, cortisol, insulin, and glucose levels. RESULTS: Peak hyperleptinemia occurred after 16 hours of HC infusion; peak/baseline leptin levels were 129% (placebo), 140% (30 mg of HC for 24 hours, p = 0.05), and 185% (100 mg of HC for 24 hours, p < 0.01). During infusion of HC (300 mg/24 hours or placebo), the peak/baseline plasma leptin levels were 16.1 +/- 5.8/12.8 +/- 5.9 ng/mL (placebo with food, 126%), 14.6 +/- 6.0/12.5 +/- 6.5 ng/mL (HC fasting, 117%), and 32.5 +/- 12.5/12.0 +/- 8.4 ng/mL (HC with food, 271%, p < 0.001). DISCUSSION: Leptin secretory responses occur at physiological doses of HC, are obliterated by fasting, and thus may be of metabolic significance.     

Effects of short-term,integrated body mass reduction program on maximal oxygen consumption and anaerobic alactic performance in obese subjects

The study investigated the effect of a short-term (3-week) body mass reduction program, combining energy-restricted diet, nutritional education, psychological counselling and aerobic exercise training (DEP-AT) on maximal oxygen consumption (VO2max) and anaerobic alactic performance evaluated with different techniques in obese patients (grade II and III). Fifty-three (14 males, 39 females) obese subjects [average +/- SD body mass index (BMI): 41.6 +/- 4.2 kg/m2] were tested before and after the DEP-AT program characterised by a daily conditioning protocol of aerobic exercise on cycloergometer, treadmill and armergometer for a total duration of 35 min at an intensity corresponding to 50% of individual VO2max during the first week of the program and at 60% in the following 2 weeks. VO2max was determined with the cycloergometric indirect method. Short-term alactic anaerobic performance was evaluated with: a) jumping test (5 consecutive jumps with maximal effort, Bosco technique), b) short sprint running test (8m), and c) stair climbing test (modified Margaria test). The DEP-AT program induced a significant weight loss (-4.57 +/- 1.26%, p < 0.001) and a significant VO2max increase (14.1 +/- 20.5%, p < 0.001). After the DEP-AT program, lower limb alactic anaerobic power output, calculated on a per kg body mass basis, increased significantly both in jumping and in stair climbing (20.1 +/- 24.8%, p < 0.001 and 13.5 +/- 19.75%, p < 0.001, respectively), as well as average horizontal velocity during short sprinting (7.2 +/- 17.6%, p < 0.01). Power output was a major determinant of the motor performance, being significantly correlated with: a) vertical displacement of the centre of gravity (R2 = 0.884, p < 0.001) in jumping test, b) vertical velocity (R2 = 0.348, p < 0.001) in stair climbing test, and c) horizontal velocity (R2 = 0.394, p < 0.001) in short running test. In conclusion, short-term DEP-AT program induces significant improvements in both aerobic capabilities and anaerobic performance, possibly through the combination of a number of contributory mechanisms, such as exercise-mediated training, shift in the balance between parasympathetic and sympathetic activity, a weight-loss dependent shift toward a more favourable region of the muscle power-velocity curve, acquisition of a certain degree of motor skill during the conditioning program, improvement of self-esteem and motivation.     

Evaluation of peripheral muscle oxygenation during exercise by spatially resolved spectroscopy in patients with chronic obstructive pulmonary disease

BACKGROUND: Spatially resolved (SR) spectroscopy has enabled non-invasive and continuous measurement of muscle oxygen saturation during exercise. In patients with chronic obstructive pulmonary disease (COPD), skeletal muscle dysfunction has been widely studied histochemically and biochemically. However, impairment of muscle oxygenation during exercise has not been elucidated yet. METHODS: We measured oxygen saturation in the vastus lateralis muscle (SmO2) using SR spectrometry during incremental cycle exercise in 16 COPD patients and 10 age-matched healthy subjects. RESULTS: Significant decrease in SmO2 was found at peak exercise compared with warm-up in both groups (56.9 +/- 6.0% to 47.3 +/- 6.8% in patients with COPD, p<0.001; 60.7 +/- 5.8% to 49.9 +/- 7.7% in healthy subjects, p<0.01). The decrease in SmO2 was linear with respect to increase in work rate, and the slope of SmO2 was significantly steeper in COPD patients than in healthy subjects (-0.282 +/- 0.159 vs -0.107 +/- 0.057 %/Watt, p<0.001). The slope of SmO2 in COPD patients significantly correlated with body mass index (BMI) (p<0.01), peak percutaneous oxygen saturation (p<0.05), and peak pulmonary oxygen consumption (p<0.05). Stepwise regression analysis revealed that BMI was a significant determinant of the SmO2 slope (p=0.01). CONCLUSIONS: We conclude that oxygenation of peripheral muscle is impaired during exercise in COPD patients and that BMI contributes independently to the change of muscle oxygen saturation with exercise in COPD patients. SR spectroscopy will provide useful information for the study of the dynamics of muscle oxygenation in COPD patients.     

Noninvasive assessment of left ventricular function in asymptomatic diabetics and its relation to metabolic control and microangiopathy

Fifty otherwise healthy patients with diabetes mellitus (37 males, 13 females; mean age: 53 +/- 10 years) of more than five year duration were compared with twenty six healthy age and sex matched controls. Detailed echocardiographic evaluation was done in all and systolic time intervals (STI) were measured. In diabetics, metabolic control and presence of microangiopathy were evaluated. PEP Index (patients: 146.23 +/- 17.04; controls: 121.99 +/- 5.15; p less than 0.001), PEP/LVET ratio (patients: 0.38 +/- 0.07; controls: 0.32 +/- 0.02; p less than 0.001), LVEF% (patients: 54.1 +/- 10.56; controls: 64.71 +/- 6.33; p less than 0.001), all were significantly altered in diabetics suggesting left ventricular dysfunction. The left ventricular posterior wall thickness (patients: 0.96 +/- 0.23 cm; controls: 0.85 +/- 0.12 cm; p less than 0.01) and interventricular septal thickness (patients: 1.2 +/- 0.24 cm; controls: 0.87 +/- 0.25 cm; p less than 0.001) in diastole were increased in diabetics. The PEPI correlated with day-to-day control but not with chronic glycemic control of diabetes mellitus. The PEP/LVET was significantly increased in patients with severe, as compared to those with none or mild microangiopathy (p less than 0.05). Thus, significant left ventricular dysfunction is evident in asymptomatic, otherwise healthy diabetics. Both metabolic control and microangiopathy may be responsible for the abnormalities.     

大气污染对人体心肺功能的影响

目的探讨大气污染对健康人体心肺功能的危害。方法在污染较严重的地区选取15名健康成年人作为污染组(EG),同时在洁净区选取相同人群作为对照组(CG)。用国产台式血压计测量安静状态下动脉血压,FHL-Ⅱ型肺活量计测量安静肺活量。用意大利Cosmed公司生产的quark b2型运动心肺功能检测系统,对受试者递增负荷踏车运动过程中心肺功能水平进行测试。结果安静状态EG除心率(HR)高于、肺活量(VC)低于CG(P<0.01,P<0.05)外,其余指标两组间无显著差异。运动负荷量达到无氧阈(AT)状态时,摄氧量绝对值(VO2)、摄氧量相对值(VO2/kg)、氧脉搏(O2P)、代谢当量(METS)几项指标CG均显著高于EG(P<0.05,P<0.01)。运动负荷量达到最大摄氧量(VO2max)状态时,VO2max、最大摄氧量相对值(VO2max/kg)、O2P、METS、运动持续时间(DT)等指标CG均显著高于EG(P<0.01),但EG运动后心率恢复较CG缓慢。结论大气污染给人体心肺功能水平和储备能力均带来不良影响。动态心肺功能评价指标更能全面准确评价大气污染等不良因素对人体心肺功能的潜在危害。     

Effect of smoking on weight and cardiopulmonary capacities in young athletes

The aim of the study was to determine wether smokers practising sports have reduced weight, if recuperation time after moderate exercise and maximal aerobic power were lowered. Thousand young soldiers [50 smokers (S), 50 no smokers (NS)] averaging 24 years in age were studied. The subjects performed to exhaustion on Ruffier test, then a maximal exercise with Cooper test. Several biometrical and physiological parameters were evaluated: weight (W), percent of body fat (PBF), body mass index (BMI), maximal oxygen uptake (VO2 max) and recuperation index (RI). Kinetics of heart rate (HR) were studied for 7 min considering time constant (1 min) and delay for recovery. The smokers showed significant differences for W (p < 0.001), PBF (p < 0.05), VO2 max (p < 0.01) and recuperation index (p < 0.001). Maximal aerobic power were 45.8 +/- 2.7 and 50.3 +/- 3.2 ml/kg/min for S and NS, and RI were 7.5 +/- 0.9 (S) and 5.0 +/- 1 (NS). figure 1 shows that HR recovery of S has generally two components: the first was fast, the second was a slone none. The smokers who presented a great dependence to tobacco smoking had a significant lower RI (p < 0.001) as those subjects with little tobacco dependence (Table 5). The smokers had lower values of VO2 max, and there exists a tobacco dependence difference. Recuperation time for the aerobically well trained S subjects was more rapid during the lactic phase. Note that correlations obtained between the VO2 max and RI were significant (r = - 0.788; p < 0.05). The smokers and no smokers differences are discussed with reference to nicotinemia effects and the sympathetic-parasympathetic unbatance of influences. The comparison of smokers groups concerning cardiovascular data led to suppose that there exists a tobacco dependence difference in regards of the catecholaminergic sensitivity. In conclusion, this study showed that smoker practising a physical activity have a reduced weight, a higher recuperation time and an anaerobic limitation influenced by the state of tobacco dependence.     

Cordyceps Sinensis (CordyMax Cs-4) supplementation does not improve endurance exercise performance

It is purported that supplementation with Cordyceps Sinensis (CordyMax Cs-4) will improve oxidative capacity and endurance performance. The intent of this investigation was to examine the effects of CordyMax Cs-4 supplementation on VO<(2peak,) ventilatory threshold, and endurance performance in endurance-trained cyclists. Twenty-two male cyclists participated in 5 weeks of supplementation with CordyMax Cs-4 tablets (3 g/d). Training intensity was maintained by weekly documentation and reporting throughout the 5-week period. Subjects completed a VO(2peak) test and work-based time trial prior to and following the supplementation period. VO(2peak) was similar within and between placebo (PLA) and treatment (CS) groups prior to (59.9 +/- 5.9 vs. 59.1 +/- 5.4 ml/kg/min, respectively) and following (60.1 +/- 5.5 vs. 57.1 +/- 5.8 ml/kg/min, respectively) the supplementation period. Ventilatory threshold (VT) was measured at 72 +/- 10% of VO(2peak) in P and T prior to supplementation and did not change in either group following the supplementation. PLA completed the time trial in 61.4+/- 2.4 min compared to 62.1+/- 4.0 min in T. Time trial measurements did not differ between groups, nor did they change in response to supplementation. It is concluded that 5 weeks of CordyMax Cs-4 supplementation has no effect on aerobic capacity or endurance exercise performance in endurance-trained male cyclists.     

Effects of pressure-demand respirator wear on physiological and perceptual variables during progressive exercise to maximal levels

Current regulations governing the certification of respiratory protective devices are based on data published in the early 1950s. The limited data base of this early work and documented increases in the average height of the population underscore the need for additional information concerning the parameters of certification. In the present study, a protocol using an inclined treadmill (0.5% grade every 12 sec) was used to test a heterogeneous population (n = 38). Through submaximal up to and including maximal exercise levels with and without respirator wear, maximal oxygen uptake (VO2max) was significantly greater (p less than 0.01) with the respirator (44.11 +/- 1.3 mL/kg.min) than without the respirator (42.18 +/- 1.4 mL/kg.min) while maximal ventilation volumes (VEmax) were not significantly different (with = 118.7 +/- 4 L/min; without 119.6 +/- 5 L/min). While peak inspired flows (PFI) with the respirator (268 +/- 7 L/min) were less than without the respirator (281 +/- 9 L/min), p greater than 0.05, the lower peak expired flow (PFE) with the respirator (289 +/- 12 L/min) than without the respirator (324 +/- 13 L/min), p less than 0.01, indicated a significant blunting effect of the respiratory flows by the expired resistance during exercise to maximal levels. Peak inspired pressures (PPi) with and without the respirator were not significantly different (p greater than 0.05). The negative values obtained within the facepiece of the respirator (-7.65 +/- 0.8 cmH2O), however, indicate that the positive pressure within the facepiece was lost, and respiratory protection may be compromised. Peak expired pressure with the respirator (13.05 +/- 0.7 cmH2O) was significantly greater than without the respirator (10.7 +/- 0.5 cmH2O) indicating that, despite a lower PFE, greater force was required to overcome the resistances of the respirator on expiration. The dyspnea index, an index of physiological effort; suggests that the subjects were working at a higher percentage of their respiratory reserve with the respirator (p less than 0.05) than without. Perceptually, subjects also felt that breathing with the respirator was more difficult (p less than 0.05). The maximum heart rate and the ratings of perceived exertion were not significantly different between the two tests at maximal exercise levels. Maximum oxygen uptake was considered reached when subjects attained a respiratory exchange ratio of at least 1.15, when a heart rate response at or greater than age-predicted maximum was achieved, when ratings of perceived exertion indicated exhaustion, and/or when the measure of VO2 had plateaued during the final minute of exercise.(ABSTRACT TRUNCATED AT 400 WORDS)     

A patient with a severe chronic airway obstruction and preserved exercise capacity (a case report)

We report a patient with chronic obstructive pulmonary disease (COPD) in whom severe lung function disorders are combined with completely preserved exercise capacity. We assessed the exercise capacity of a 44-year-old man (height 155 cm, BMI 19.6 kg.m-2, FEV1%pred. = 30.9%, FRC%pred. = 158%, KCO%pred. = 46.2%, PaO2 = 64.0 mmHg, Medical Research Council Dyspnea scale = 1, Baseline Dyspnea Index = 10) by the 6-minute walking distance test (6MWD) and the symptom-limited cardiopulmonary exercise test (CPET) on a treadmill using the Bruce protocol. The patient was able to walk 667 meters in the test and achieved peak relative oxygen consumption (VO2/kg) of 21.9 mL.min-1.kg-1. We attribute the preserved exercise capacity of the patient to the combined beneficial effect of the following factors: 1. Efficient extraction of the hemoglobin-transported oxygen from the alveoli (P50 = 3.10 kPa). 2. Optimal right ventricle remodelling with mild hypertrophy, without dilatation and congestion. 3. Hypoxic normoxemia without polyglobulia, resulting in good rheologic properties of blood. 4. A preserved locomotory activity of the patient. Such a combination of severe lung function disorders with mildly pronounced dyspnea and preserved exercise capacity supports the concept that the function profile of COPD patients is multidimensional and therefore such patients should have a complete assessment of their disability condition.     

Effect of active versus passive recovery on metabolism and performance during subsequent exercise

This study tested the hypothesis that active recovery between bouts of intense aerobic exercise would lead to better maintenance of exercise performance in the second bout of exercise. Seven trained men on 2 separate occasions (VO(2peak) = 58.3+/- 9.4 ml x kg(-1) x min(-1)) performed as much work as possible during two 20-min cycling exercise bouts, separated by a 15-min recovery period. During passive recovery (PR), subjects rested supine, while during active recovery (AR) subjects continued to cycle at 40% VO(2peak). Muscle biopsies and blood samples were obtained. Neither muscle glycogen or lactate was different when comparing AR with PR at any point. In contrast, plasma lactate concentration was higher (p<.05) in PR versus AR during the recovery period, such that subjects commenced the second bout of intense exercise with a lower (p <.05) plasma lactate concentration in AR (4.4 +/- 0.7 vs. 7.7 +/- 1.4 mmol. L(-1) following AR and PR, respectively). Work performed in Bout 2 was less than that performed in Bout 1 in both trials (p<.01), with no difference in work performed between trials. These data do not support the benefit of AR when compared to PR in the maintenance of subsequent intense aerobic exercise performance.     

Basal and stimulated plasma leptin in diabetic subjects

OBJECTIVE: To determine whether leptin secretion is impaired in diabetes, we compared basal and stimulated plasma leptin levels in diabetic subjects and healthy controls. RESEARCH METHODS AND PROCEDURES: Blood samples for assay of leptin and other hormones were obtained at baseline in 54 diabetic patients and 65 controls, and 8 hours, 16 hours, and 40 hours following ingestion of dexamethasone (4 mg) in 6 healthy and 12 controls. C-peptide status was defined as "negative" if < or =0.1 ng/mL or "positive" if > or =0.3 ng/mL, in fasting plasma. RESULTS: Basal plasma leptin levels were 19.7+/-2.2 ng/mL in nondiabetic subjects, 13.4+/-1.5 ng/ml in C-peptide negative (n = 28) and 26.1+/-3.7 ng/mL in C-peptide positive (n = 26, p = 0.001) diabetic patients. Dexamethasone increased leptin levels of controls (n = 6) to 145+/-17% of baseline values at 8 hours (p = 0.03), 224+/-18% at 16 hours (p = 0.01), and 134+/-18% at 40 hours (p=0.05). The corresponding changes were 108+/-13%, 126+/-23%, and 98+/-16% in C-peptide negative (n=6), and 121+/-10%, 144+/-16% (p=0.03), and 147+/-23% (p=0.11) in C-peptide positive (n = 6) diabetic patients, respectively. The peak stimulated leptin levels were lower in the diabetic patients, compared with controls. Plasma insulin increased (p = 0.02) in controls, but not in the diabetic patients, following dexamethasone. DISCUSSION: Although diabetic patients have normal plasma leptin levels under basal conditions, their leptin responses to glucocorticoid are impaired, probably because of the concomitant insulin secretory defect. A subnormal leptin secretory response could worsen obesity and insulin resistance in diabetes.     

The effect of a high carbohydrate meal on endurance running capacity

This study examined the effects of a pre-exercise meal and a carbohydrate-electrolyte solution on endurance running capacity. Ten men performed 3 treadmill runs at 70% VO2max to exhaustion after consuming (a) a carbohydrate meal 3 h before exercise and a carbohydrate-electrolyte solution during exercise (M + C); or (b) the carbohydrate meal 3 h before exercise and water during exercise (M + W); or (c) a liquid placebo 3 h before exercise and water during exercise (P + W). Exercise time was longer in M + C (125.1 +/- 5.3 min; mean +/- SE) and M + W (111.9 +/- 5.6 min) compared with P + W (102.9 +/- 7.9 min; p < .01 and p < .05, respectively), and longer in M + C compared with M + W (p < .05). Serum insulin concentration at the start of exercise and carbohydrate oxidation rates during the first hour of exercise were higher, whereas plasma FFA concentrations throughout exercise were lower in M + W and M + C than in P + W (p < .01). A carbohydrate meal before exercise at 70% VO2max improved endurance running capacity; however, the combination of the meal and a carbohydrate-electrolyte solution during exercise further improved endurance running capacity.