Home About us Contact
|
Home About us Contact | ||
|
|
||
Exercise Performance (exercise + performance)
Selected AbstractsCerebral oxygenation decreases but does not impair performance during self-paced, strenuous exerciseACTA PHYSIOLOGICA, Issue 4 2010F. Billaut Abstract Aim:, The reduction in cerebral oxygenation (Cox) is associated with the cessation of exercise during constant work rate and incremental tests to exhaustion. Yet in exercises of this nature, ecological validity is limited due to work rate being either fully or partly dictated by the protocol, and it is unknown whether cerebral deoxygenation also occurs during self-paced exercise. Here, we investigated the cerebral haemodynamics during a 5-km running time trial in trained runners. Methods:, Rating of perceived exertion (RPE) and surface electromyogram (EMG) of lower limb muscles were recorded every 0.5 km. Changes in Cox (prefrontal lobe) were monitored via near-infrared spectroscopy through concentration changes in oxy- and deoxyhaemoglobin (,[O2Hb], ,[HHb]). Changes in total Hb were calculated (,[THb] = ,[O2Hb] + ,[HHb]) and used as an index of change in regional blood volume. Results:, During the trial, RPE increased from 6.6 ± 0.6 to 19.1 ± 0.7 indicating maximal exertion. Cox rose from baseline to 2.5 km (,,[O2Hb], ,,[HHb], ,,[THb]), remained constant between 2.5 and 4.5 km, and fell from 4.5 to 5 km (,,[O2Hb], ,,[HHb], ,,[THb]). Interestingly, the drop in Cox at the end of the trial coincided with a final end spurt in treadmill speed and concomitant increase in skeletal muscle recruitment (as revealed by higher lower limb EMG). Conclusion:, Results confirm the large tolerance for change in Cox during exercise at sea level, yet further indicate that, in conditions of self-selected work rate, cerebral deoxygenation remains within a range that does not hinder strenuous exercise performance. [source] Assessment of physical fitness for esophageal surgery, and targeting interventions to optimize outcomesDISEASES OF THE ESOPHAGUS, Issue 7 2010C. Feeney SUMMARY This review examines how higher levels of physiological reserve and fitness can help the patient endure the demands of esophageal surgery. Lung function, body composition, cardiac function, inflammatory mediators and exercise performance are all determinants of fitness. Physical fitness, both as an independent risk factor and through its effect on other risk factors, has been found to be significantly associated with the risk of developing postoperative pulmonary complications (PPCs) in patients following esophagectomy. Respiratory dysfunction preoperatively poses the dominant risk of developing complications, and PPCs are the most common causes of morbidity and mortality. The incidence of PPCs is between 15 and 40% with an associated 4.5-fold increase in operative mortality leading to approximately 45% of all deaths post-esophagectomy. Cardiac complications are the other principal postoperative complications, and pulmonary and cardiac complications are reported to account for up to 70% of postoperative deaths after esophagectomy. Risk reduction in patients planned for surgery is key in attaining optimal outcomes. The goal of this review was to discuss the risk factors associated with the development of postoperative pulmonary complications and how these may be modified prior to surgery with a specific focus on the pulmonary complications associated with esophageal resection. There are few studies that have examined the effect of modifying physical fitness pre-esophageal surgery. The data to date would indicate a need to develop targeted interventions preoperatively to increase physical function with the aim of decreasing postoperative complications. [source] Screening for the calstabin-ryanodine receptor complex stabilizers JTV-519 and S-107 in doping control analysisDRUG TESTING AND ANALYSIS, Issue 1 2009Mario Thevis Abstract Recent studies outlined the influence of exercise on the stability of the skeletal muscle calstabin1-ryanodine receptor1-complex, which represents a major Ca2+ release channel. The progressive modification of the type-1 skeletal muscle ryanodine receptor (RyR1) combined with reduced levels of calstabin1 and phosphodiesterase PDE4D3 resulted in a Ca2+ leak that has been a suggested cause of muscle damage and impaired exercise capacity. The use of 1,4-benzothiazepine derivatives such as the drug candidates JTV-519 and S-107 enhanced rebinding of calstabin1 to RyR1 and resulted in significantly improved skeletal muscle function and exercise performance in rodents. Due to the fact that the mechanism of RyR1 remodelling under exercise conditions were proven to be similar in mice and humans, a comparable effect of JTV-519 and S-107 on trained athletes is expected, making the compounds relevant for doping controls. After synthesis of JTV-519, S-107, and a putative desmethylated metabolite of S-107, target compounds were characterized using nuclear magnetic resonance spectroscopy and electrospray ionization (ESI),high-resolution/high-accuracy Orbitrap mass spectrometry. Collision-induced dissociation pathways were suggested based on the determination of elemental compositions of product ions and H/D-exchange experiments. The most diagnostic product ion of JTV-519 was found at m/z 188 (representing the 4-benzyl-1-methyl piperidine residue), and S-107 as well as its desmethylated analog yielded characteristic fragments at m/z 153 and 138 (accounting for 1-methoxy-4-methylsulfanyl-benzene and 4-methoxy-benzenethiol residues, respectively). The analytes were implemented in existing doping control screening procedures based on liquid chromatography, multiple reaction monitoring and simultaneous precursor ion scanning modes using a triple quadrupole mass spectrometer. Validation items such as specificity, recovery (68,92%), lower limit of detection (0.1,0.2 ng/mL), intraday (5.2,18.5%) and interday (8.7,18.8%) precision as well as ion suppression/enhancement effects were determined. Copyright © 2009 John Wiley & Sons, Ltd. [source] Atorvastatin therapy improves exercise oxygen uptake kinetics in post-myocardial infarction patientsEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 6 2007M. Guazzi Abstract Background Statins represent a modern mainstay of the drug treatment of coronary artery disease and acute coronary syndromes. Reduced aerobic work performance and slowed VO2 kinetics are established features of the clinical picture of post-myocardial infarction (MI) patients. We tested the hypothesis that statin therapy improves VO2 exercise performance in normocholesterolaemic post-MI patients. Materials and methods, According to a double-blinded, randomized, crossover and placebo-controlled study design, in 18 patients with uncomplicated recent (3 days) MI we investigated the effects of atorvastatin (20 mg day,1) on gas exchange kinetics by calculating VO2 effective time constant (tau) during a 50-watt constant workload exercise, brachial artery flow-mediated dilatation (FMD) as an index of endothelial function, left ventricular function (echocardiography) and C-reactive protein (CRP, as an index of inflammation). Atorvastatin or placebo was given for 3 months each. Results, Atorvastatin therapy significantly improved exercise VO2 tau and FMD, and reduced CRP levels. We did not observe changes in cardiac contractile function and relaxation properties during all study periods in either group. Conclusions, In post-MI patients exercise performance is a potential additional target of benefits related to statin therapy. Endothelial function improvement is very likely implicated in this newly described therapeutic property. [source] Differential effects of acute and chronic exercise on plasticity-related genes in the rat hippocampus revealed by microarrayEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2002Raffaella Molteni Abstract Studies were performed to determine the effects of acute and chronic voluntary periods of exercise on the expression of hippocampal genes. RNAs from rodents exposed to a running wheel for 3, 7 and 28 days were examined using a microarray with 1176 cDNAs expressed primarily in the brain. The expression of selected genes was quantified by Taqman RT-PCR or RNase protection assay. The largest up-regulation was observed in genes involved with synaptic trafficking (synapsin I, synaptotagmin and syntaxin); signal transduction pathways (Ca2+/calmodulin-dependent protein kinase II, CaM-KII; mitogen-activated/extracellular signal-regulated protein kinase, MAP-K/ERK I and II; protein kinase C, PKC-,) or transcription regulators (cyclic AMP response element binding protein, CREB). Genes associated with the glutamatergic system were up-regulated (N -methyl- d -aspartate receptor, NMDAR-2A and NMDAR-2B and excitatory amino acid carrier 1, EAAC1), while genes related to the gamma-aminobutyric acid (GABA) system were down-regulated (GABAA receptor, glutamate decarboxylase GAD65). Brain-derived neurotrophic factor (BDNF) was the only trophic factor whose gene was consistently up-regulated at all timepoints. These results, together with the fact that most of the genes up-regulated have a recognized interaction with BDNF, suggest a central role for BDNF on the effects of exercise on brain plasticity. The temporal profile of gene expression seems to delineate a mechanism by which specific molecular pathways are activated after exercise performance. For example, the CaM-K signal system seems to be active during acute and chronic periods of exercise, while the MAP-K/ERK system seems more important during long-term exercise. [source] Contractile Properties, Fatigue and Recovery are not Influenced by Short-Term Creatine Supplementation in Human MuscleEXPERIMENTAL PHYSIOLOGY, Issue 4 2000J. M. Jakobi There have been several studies on the effect of short-term creatine (Cr) supplementation on exercise performance, but none have investigated both voluntary and stimulated muscle contractions in the same experiment. Fourteen moderately active young men (19-28 years) were randomly assigned, in a double blind manner, to either a creatine (Cr) or placebo (P) group. The subjects supplemented their regular diet 4 times a day for 5 days with either 5 g Cr + 5 g maltodextrin (Cr group), or 5 g maltodextrin (P group). Isometric maximal voluntary contraction (MVC), muscle activation, as assessed using the modified twitch interpolation technique, electrically stimulated contractile properties, electromyography (EMG), endurance time and recovery from fatigue were measured in the elbow flexors. The fatigue protocol involved both voluntary and stimulated contractions. Following supplementation there was a significant weight gain in the Cr group (1.0 kg), whereas the P group did not change. For each group, pre-supplementation measures were not significantly different from post-supplementation for MVC, twitch and tetanic tensions at rest, time to peak tension, half-relaxation time and contraction duration. Prior to Cr supplementation time to fatigue was 10 ± 4 min (mean ± S.E.M.) for both groups, and following supplementation there was a non-significant increase of 1 min in each group. MVC force, muscle activation, EMG, stimulated tensions and durations were similar for the Cr and P groups over the course of the fatigue protocol and did not change after supplementation. Furthermore, recovery of MVC, stimulated tensions and contractile speeds did not differ as a result of Cr supplementation. These results indicate that short-term Cr supplementation does not influence isometric elbow flexion force, muscle activation, stimulated contractile properties, or delay time to fatigue or improve recovery. [source] Metabolic therapy in the treatment of ischaemic heart disease: the pharmacology of trimetazidineFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 2 2003William C. Stanley Abstract The primary result of myocardial ischaemia is reduced oxygen consumption and adenosine triphosphate (ATP) formation in the mitochondria, and accelerated anaerobic glycolysis, lactate accumulation and cell acidosis. Classic pharmacotherapy for demand-induced ischaemia is aimed at restoring the balance between ATP synthesis and breakdown by increasing the oxygen delivery (i.e. with long acting nitrates or Ca2+ channel antagonist) or by decreasing cardiac power by reducing blood pressure and heart rate (i.e. with , -blocker or Ca2+ channel antagonist). Animal studies show that fatty acids are the primary mitochondrial substrate during moderate severity myocardial ischaemia, and that they inhibit the oxidation of carbohydrate and drive the conversion of pyruvate to lactate. Drugs that partially inhibit myocardial fatty acid oxidation increase carbohydrate oxidation, which results in reduced lactate production and a higher cell pH during ischaemia. Trimetazidine (1-[2,3,4-trimethoxibenzyl]-piperazine) is the first and only registered drug in this class, and is available in over 90 countries world-wide. Trimetazidine selectively inhibits the fatty acid , -oxidation enzyme 3-keto-acyl-CoA dehydrogenase (3-KAT), and is devoid of any direct haemodynamic effects. In double-blind placebo-controlled trials trimetazidine significantly improved symptom-limited exercise performance in stable angina patients when used either as monotherapy or in combination with , -blockers or Ca2+ channel antagonists. Given available evidence, trimetazidine is an excellent alternative to classic haemodynamic agents, and is unique in its ability to reduce symptoms of angina when used in patients resistant to a haemodynamic treatment as vasodilators, , -blockers or Ca2+ channel antagonists. [source] Endurance Exercise Training in Older Patients with Heart Failure: Results from a Randomized, Controlled, Single-Blind TrialJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 11 2009Peter H. Brubaker PhD OBJECTIVES: To test the hypothesis that exercise training (ET) improves exercise capacity and other clinical outcomes in older persons with heart failure with reduced ejection fraction (HfrEF). DESIGN: Randomized, controlled, single-blind trial. SETTING: Outpatient cardiac rehabilitation program. PARTICIPANTS: Fifty-nine patients aged 60 and older with HFrEF recruited from hospital records and referring physicians were randomly assigned to a 16-week supervised ET program (n=30) or an attention-control, nonexercise, usual care control group (n=29). INTERVENTION: Sixteen-week supervised ET program of endurance exercise (walking and stationary cycling) three times per week for 30 to 40 minutes at moderate intensity regulated according to heart rate and perceived exertion. MEASUREMENTS: Individuals blinded to group assignment assessed four domains pivotal to HFrEF pathophysiology: exercise performance, left ventricular (LV) function, neuroendocrine activation, and health-related quality of life (QOL). RESULTS: At follow-up, the ET group had significantly greater exercise time and workload than the control group, but there were no significant differences between the groups for the primary outcomes: peak exercise oxygen consumption (VO2 peak), ventilatory anaerobic threshold (VAT), 6-minute walk distance, QOL, LV volumes, EF, or diastolic filling. Other than serum aldosterone, there were no significant differences after ET in other neuroendocrine measurements. Despite a lack of a group "training" effect, a subset (26%) of individuals increased VO2 peak by 10% or more and improved other clinical variables as well. CONCLUSION: In older patients with HFrEF, ET failed to produce consistent benefits in any of the four pivotal domains of HF that were examined, although the heterogeneous response of older patients with HFrEF to ET requires further investigation to better determine which patients with HFrEF will respond favorably to ET. [source] Metabolic responses to oral tryptophan supplementation before exercise in horsesJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 3-6 2005I. Vervuert Summary This study was conducted to evaluate the effects of oral tryptophan (Trp) supplementation on exercise capacity and metabolic responses in horses. Three horses had to perform an exercise test: a 15-min warm-up followed by a 60-min walk (1.7 m/s, W1), a 10-min trot (3.1 m/s, T1), a second 60-min walk (1.7 m/s, W2), a second 10-min trot (3.1 m/s, T2) and a final 30-min walk (1.7 m/s, W3) until the horses were unwilling to continue. The horses exercised on a treadmill at a 6% incline and with a constant draught load of 40 kg (0.44 kN). Two hours before exercise horses were given 50 g Trp (9.8,10.7 g Trp/100 kg BW) by nasogastric tube. A control exercise test was conducted without Trp. During the control test, one horse was able to finish the final 30-min walk (W3), whereas two horses finished W3 after Trp administration. Higher plasma Trp levels after Trp administration did not change significantly during exercise (Trp: start exercise, 524 ± 41 ,mol/l; end exercise 547 ± 20 ,mol/l; control: start exercise, 70 ± 10 ,mol/l; end exercise, 58 ± 21 ,mol/l). After Trp supplementation, blood lactate concentrations were significantly lower after the first and second trotting periods. Free fatty acids in plasma increased during exercise without any treatment-related differences. Although experimental plasma Trp levels were seven times higher than the control levels, Trp supplementation had no effect on exercise performance and metabolic responses to draught load exercise. [source] The effect of a pulmonary rehabilitation programme on older patients with chronic pulmonary diseaseJOURNAL OF CLINICAL NURSING, Issue 1 2008Kim Ae Kyung RN Aim., The aim of this study was to answer the question: is there an effect on the respiratory capacity and activity tolerance of older patients with chronic obstructive pulmonary disease who participate in a pulmonary rehabilitation programme? Background., Pulmonary rehabilitation is now an integral part of chronic obstructive pulmonary disease management. Evidence supports the positive effects of breath training and exercising training on quality of life, exercise tolerance and improved physical condition of individual with chronic obstructive pulmonary disease. Limited empirical documentation exists to support the effectiveness of a nurse managed rehabilitation programme for older patients with chronic obstructive pulmonary disease. The study was done to evaluate the effects of pulmonary rehabilitation provided by nurses on the pulmonary function, gas exchange and exercise tolerance in older patients with chronic obstructive pulmonary disease. Design., A one group pre-test,post-test design was used to evaluate the effects of a pulmonary rehabilitation programme. Method., The sample consisted of 20 patients with chronic obstructive pulmonary disease who participated in a pulmonary rehabilitation programme including breathing exercises, upper-limb exercises and inspiratory muscle training. Results., The findings indicated improvement in exercise performance and a decrease in dyspnea after participation in the pulmonary rehabilitation programme. Relevance to clinical practice., The clinical nurse can make a significant impact on the illness trajectory and quality of life for patients with chronic obstructive pulmonary disease. The nurse has a critical role in helping patient with chronic obstructive pulmonary disease learn to cope, adjust and adapt to life with a chronic illness. Active nurse involvement with a patient in a pulmonary rehabilitation programme can assist in the identification of factors that motivate the patient, help in establishing realistic out comes expectations and provide patient teaching opportunities. The nurse can assist the patient to develop skills of self-awareness regarding particular symptoms, self-monitoring and health status change identification. [source] Physical activity and exercise performance predict long-term prognosis in middle-aged women surviving acute coronary syndromeJOURNAL OF INTERNAL MEDICINE, Issue 2 2007F. Al-Khalili Abstract. Aim., To evaluate the importance of exercise testing (ET) parameters and leisure time physical activity in predicting long-term prognosis in middle-aged women hospitalized for acute coronary syndrome (ACS). Methods and results., Women aged <66 years recently hospitalized for ACS in the Greater Stockholm area in Sweden were recruited. All underwent baseline clinical examinations including ET and then were followed up for 9 years. Nonparticipation in ET had a hazard ratio of 4.26 (95% confidence interval 2.02,8.95) for total mortality and 3.03 (1.03,8.91) for cardiovascular mortality. All ET parameters were significantly different between survivors than nonsurvivors, except for chest pain and ST-segment depression during ET. Sedentary lifestyle and ET parameters were related to total mortality and cardiovascular mortality in a multivariate analysis adjusting for potential confounders. Predictors of total mortality were sedentary lifestyle 2.94 (1.31,6.62), exercise time 1.75 (1.07,2.87) and inadequate haemodynamic responses: low increase in pulse rate 2.04 (1.16,3.60) and systolic blood pressure (SBP) 1.88 (1.19,2.95) from rest to peak exercise. Parameters that predicted cardiovascular mortality were sedentary lifestyle 3.15 (1.13,8.74) and poor increase in SBP 2.76 (1.30,5.86) from rest to peak exercise. The relation of sedentary lifestyle to survival was substantially weakened when exercise parameters were added to the multivariate analysis model. Conclusion., In female patients <66 years surviving ACS, important independent predictors of long-term all-cause mortality were sedentary lifestyle, low physical fitness and inadequate pulse rate and SBP increase during exercise. Predictors of cardiovascular mortality were sedentary lifestyle and inadequate blood pressure response during exercise. [source] Physiological and performance effects of glycerol hyperhydration and rehydrationNUTRITION REVIEWS, Issue 12 2009Simon P Van Rosendal Studies have shown that beverages containing glycerol can enhance and maintain hydration status and may improve endurance exercise performance by attenuating adverse physiological changes associated with dehydration. Improvements to performance include increased endurance time to exhaustion by up to 24%, or a 5% increase in power or work. However, some studies have found no performance benefits during either prolonged exercise or specific skill and agility tests. In studies that have shown benefits, the improvements have been associated with thermoregulatory and cardiovascular changes. These include increased plasma volume and sweat rates, as well as reduced core temperature and ratings of perceived exertion. In a very small number of subjects, glycerol consumption has been associated with side-effects including nausea, gastrointestinal discomfort, dizziness, and headaches. In summary, while glycerol and fluid ingestion results in hyperhydration, the documented benefits to exercise performance remain inconsistent. [source] Usefulness of a program of hospital-supervised physical training in patients with cystic fibrosisPEDIATRIC PULMONOLOGY, Issue 2 2004Attilio Turchetta MD Abstract Exercise is an important part of normal childhood, but the ability to exercise may be impaired in chronic lung diseases such as cystic fibrosis (CF). Improving exercise performance by training is very attractive. The aim of the present study was the evaluation of the effects of a physical aerobic training program, performed in the Children's Hospital and Research Institute "Bambino Gesù" (Rome, Italy) in outpatient CF children, supervised by a physician. Twelve patients (mean forced expiratory flow in 1 sec (FEV1), 71%), age range 12,24 years (16.7 ± 4.4 years), were enrolled. They performed a maximal exercise stress test on the treadmill (modified Bruce protocol) with breath-by-breath determination of oxygen consumption (VO2) to maximum at end-exercise; we measured time of exercise (TE), maximal heart rate (Hrmax) in beats per minute (bpm), and maximal systolic blood pressure (SBPm) in mmHg. The program consisted of 12 weeks of training twice a week. Each training session consisted of walking or running on the treadmill for 30 min at the speed that allowed the child to attain 60% of the maximal heart rate obtained during a baseline stress test for 4 weeks, 70% in the following 4 weeks, and 80% in the last 4 weeks, under strict medical supervision. HR was continously monitored. There was no change in FEV1 and forced vital capacity after the treatment period. Hrmax and SBPm also remained the same (P,=,0.37 and P,=,0.25, respectively). There was a significant increase in TE (P,<,0.002), VO2, VO2/kg, and pulmonary ventilation (VE) (P,<,0.0001, P,<,0.001, and P,<,0.001, respectively). This pilot study showed that a simple training program improves short-term cardiopulmonary fitness in children with CF. Further studies with a larger sample and for a more prolonged time are necessary to assess if sport can have a long-term effect on lung function or survival in CF patients. Pediatr Pulmonol. 2004; 38:115,118. © 2004 Wiley-Liss, Inc. [source] Extended-stay hospitalization for childhood asthma in JapanPEDIATRICS INTERNATIONAL, Issue 4 2009Hidekazu Tani Abstract Background:, While recent advances in asthma management have enabled adequate control to be frequently achieved in outpatient settings, children whose asthma remains poorly controlled despite outpatient treatment are often referred to extended-stay hospitals. The aim of the present study was to examine trends concerning extended-stay hospitalization and to evaluate the present status of this approach. Methods:, A retrospective study was conducted to assess changes in the number of admissions among 408 children with extended stays at Kamiamakusa General Hospital between 1989 and 2005. Medical and laboratory data of 236 patients admitted since 1994 were obtained from clinical records. Results:, The number of children with extended-stay hospitalizations since 2000 declined dramatically compared with the early 1990s, while the percentage of patients with complications of childhood asthma, such as severe atopic dermatitis, school absenteeism, and obesity, have increased significantly in the recent past. Practical benefits of extended-stay hospitalization were demonstrated by significant improvement of exercise performance and measurement of pulmonary function parameters and serum IgE concentrations by time of discharge. In addition to improvement in asthmatic symptoms, maintenance drug requirements and frequency of school absenteeism were reduced. Conclusions:, The medical mission of extended-stay hospitalizations is currently limited due to the availability of improved pharmacotherapy. Some patients, however, with exceptionally severe asthma or psychological problems that interact with their medical condition still fare poorly under outpatient care and could benefit from group care. Further study is needed to identify the components of long-term programs essential to produce change. [source] Physical fitness indices and anthropometrics profiles in schoolchildren with sickle cell trait/diseaseAMERICAN JOURNAL OF HEMATOLOGY, Issue 2 2007Hisham Moheeb Abstract The current studies aimed at determining physical fitness indices and anthropometrics profiles of school children with sickle cell trait (SCT) and sickle cell disease (SCD). Male school children (150) comprising 3 Groups participated in the studies. Group 1 has 50 normal healthy controls, while Groups 2 and 3 each has 50 children who were suffering from SCT and SCD, respectively. Anthropometrics measurement and parameters of physical fitness were assessed in all subjects. All children were also subjected to a 5-min running exercise test on a flat motorized treadmill at speed corresponding to 5 km/hr. Throughout the test, heart rate was monitored and recoded during exercise and for 10-min during recovery. Blood lactate was measured before and 5 min following the completion of test. The mean values of lean body mass and height were lower in the SCD children (P < 0.05) compared with the healthy subjects and SCT individuals. Children with SCD exhibited a higher mean value (P < 0.05) for percent body fat and fat mass than the normal healthy subjects and SCT individuals. Although all groups tolerated well the treadmill exercise protocol, the SCD group exhibited higher (P < 0.05) mean values of heart rate during exercise than those observed in the SCT and normal control children. In addition, SCD children showed higher serum lactate values before and after treadmill exercise compared to the other groups. Children with SCD exhibit high level of adiposity; low level of fitness and their exercise performance appears to be physiologically more stressful as indicated by heart rate and blood lactate concentration responses. Am. J. Hematol., 2006. © 2006 Wiley-Liss, Inc. [source] Study of peripheral muscle strength and severity indexes in individuals with chronic obstructive pulmonary diseasePHYSIOTHERAPY RESEARCH INTERNATIONAL, Issue 3 2010Diego Marmorato Marino Abstract Background and Purpose.,Individuals with chronic obstructive pulmonary disease (COPD) present reduced peripheral muscle strength, which leads to impaired mobility and increased mortality risk. However, it is not clear whether there is any relationship between muscle strength, muscle mass and the body mass index, airflow obstruction, dyspnea, exercise performance (BODE) index scale, which is considered to be the best predictor of survival for individuals with COPD. The BODE Index is a multidimensional system that measures body composition (B), airway obstruction (O), dyspnea perception (D) and the ability to exercise (E), and rates the severity of the major changes found in individuals with COPD. The objective of this study was to verify any relationship between the BODE Index, muscle mass and maximum muscle strengths of the upper limb (UL) and lower limb (LL) in subjects with moderate to very severe COPD.,Methods.,Twenty-six individuals with moderate to very severe COPD were evaluated by body composition (body mass index and muscle mass), BODE Index, handgrip strength (HS) and one repetition maximum (1RM) test of the UL and LL.,Results.,There was a positive correlation (Pearson, p < 0.05) of peripheral muscle strength, evaluated by HS and 1RM (pectoral and triceps, round muscles and dorsal section, quadriceps), to muscle mass (0.74, 0.57, 0.74 and 0.62, respectively) and the distance walked in the six-minute walking test (0.52, 0.50, 0.46 and 0.58, respectively), but no correlation of muscle strength was found to forced expiratory volume in one second to dyspnea or the BODE Index.,Conclusion.,In accordance with the results of this study, peripheral muscle strength as measured y HS and 1RM is not related to the severity indexes for COPD, unlike UL and LL muscle strength. Therefore, UL and LL measurements now have an additional importance in COPD evaluation. Copyright © 2010 John Wiley & Sons, Ltd. [source] Oxygen cost of ventilation during incremental exercise to VO2 maxRESPIROLOGY, Issue 2 2006Chantal A. VELLA Objective: Evidence of significant oxygen requirements for ventilation during exercise (exercise hyperpnoea) prompted the investigation into whether the oxygen cost of ventilation affects the presence of a whole-body VO2 plateau at maximal exercise. The purposes of this study were to: (i) use isocapnic hyperpnoea trials to determine the oxygen cost of ventilation (VO2VENT) across a range of ventilation (VE); (ii) determine the mean VO2VENT at maximal exercise expressed as a percentage of whole-body VO2 max; and (iii) determine if a plateau in VO2 is more evident when the VO2VENT is subtracted from whole-body VO2 at maximal exercise. Methods: A total of 21 subjects performed a VO2 max test on the cycle ergometer to determine the range of VE for each subject. From the initial VO2 max test, nine VE values across the range of VE were selected for each subject and the oxygen cost of each was measured. Results: The mean maximal VO2VENT equalled 8.8 ± 3.3% of VO2 max and ranged from 5.0% to 17.6%. VO2VENT increased exponentially with increasing VE, but there was considerable subject variability in the oxygen cost per litre of VE as VE increased. Subtracting the VO2VENT from whole-body VO2 at maximal exercise increased the detection of a plateau in VO2 at VO2 max. Conclusions: The data of the present study indicate that the VO2VENT is a significant portion of VO2 max and may be a limiting factor of maximal exercise performance in some subjects. [source] High temperature does not alter fatigability in intact mouse skeletal muscle fibresTHE JOURNAL OF PHYSIOLOGY, Issue 19 2009Nicolas Place Intense activation of skeletal muscle results in fatigue development, which involves impaired function of the muscle cells resulting in weaker and slower contractions. Intense muscle activity also results in increased heat production and muscle temperature may rise by up to ,6°C. Hyperthermia is associated with impaired exercise performance in vivo and recent studies have shown contractile dysfunction and premature fatigue development in easily fatigued muscle fibres stimulated at high temperatures and these defects were attributed to oxidative stress. Here we studied whether fatigue-resistant soleus fibres stimulated at increased temperature show premature fatigue development and whether increasing the level of oxidative stress accelerates fatigue development. Intact single fibres or small bundles of soleus fibres were fatigued by 600 ms tetani given at 2 s intervals at 37°C and 43°C, which is the highest temperature the muscle would experience in vivo. Tetanic force in the unfatigued state was not significantly different at the two temperatures. With 100 fatiguing tetani, force decreased by ,15% at both temperatures; the free cytosolic [Ca2+] (assessed with indo-1) showed a similar ,10% decrease at both temperatures. The oxidative stress during fatigue at 43°C was increased by application of 10 ,m hydrogen peroxide or tert-butyl hydroperoxide and this did not cause premature fatigue development. In summary, fatigue-resistant muscle fibres do not display impaired contractility and fatigue resistance at the highest temperature that mammals, including humans, would experience in vivo. Thus, intrinsic defects in fatigue-resistant muscle fibres cannot explain the decreased physical performance at high temperatures. [source] Endurance exercise performance: the physiology of championsTHE JOURNAL OF PHYSIOLOGY, Issue 1 2008Michael J. Joyner Efforts to understand human physiology through the study of champion athletes and record performances have been ongoing for about a century. For endurance sports three main factors , maximal oxygen consumption , the so-called ,lactate threshold' and efficiency (i.e. the oxygen cost to generate a give running speed or cycling power output) , appear to play key roles in endurance performance. and lactate threshold interact to determine the ,performance , which is the oxygen consumption that can be sustained for a given period of time. Efficiency interacts with the performance to establish the speed or power that can be generated at this oxygen consumption. This review focuses on what is currently known about how these factors interact, their utility as predictors of elite performance, and areas where there is relatively less information to guide current thinking. In this context, definitive ideas about the physiological determinants of running and cycling efficiency is relatively lacking in comparison with and the lactate threshold, and there is surprisingly limited and clear information about the genetic factors that might pre-dispose for elite performance. It should also be cautioned that complex motivational and sociological factors also play important roles in who does or does not become a champion and these factors go far beyond simple physiological explanations. Therefore, the performance of elite athletes is likely to defy the types of easy explanations sought by scientific reductionism and remain an important puzzle for those interested in physiological integration well into the future. [source] Large Artery Stiffness: Implications For Exercise Capacity And Cardiovascular RiskCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 3 2002Bronwyn A Kingwell SUMMARY 1. Large artery stiffness, or its inverse, compliance, determines pulse pressure, which, in turn, influences myocardial work capacity and coronary perfusion, both of which impact on exercise capacity and cardiovascular risk. 2. In support of a role for arterial properties in exercise performance, aerobically trained athletes (aged 30,59 years) have lower arterial stiffness than their sedentary counterparts. Furthermore, in healthy older subjects (aged 57,80 years), time to exhaustion on treadmill testing correlated positively with arterial compliance. 3. Arterial stiffness is more closely linked to exercise capacity and myocardial risk in patients with coronary disease where, independently of degree of coronary disease, those with stiffer proximal arteries have a lower exercise-induced ischaemic threshold. 4. Moderate aerobic training elevates resting arterial compliance by approximately 30%, independently of mean pressure reduction, in young healthy individuals but not in isolated systolic hypertensive patients. Rat training studies support a role for exercise training in structural remodelling of the large arteries. 5. High-resistance strength training is associated with stiffer large arteries and higher pulse pressure than matched controls. 6. Large artery stiffness is an important modulator of the myocardial blood supply and demand equation, with significant ramifications for athletic performance and ischaemic threshold in coronary disease patients. Moderate aerobic training, but not high-resistance strength training, reduces large artery stiffness in young individuals whereas older subjects with established isolated systolic hypertension are resistant to such adaptation. [source] Medical management of significant coronary angiographic stenoses: Outcome of 60 patients observed for 433 patient yearsCLINICAL CARDIOLOGY, Issue 8 2000Charles L. Baird Jr. M.D. Abstract Background: Percutaneous transluminal coronary angioplasty (PTCA) has become routine in the management of patients with stable angina pectoris and significant coronary stenoses, while medical management of such patients has declined. Hypothesis: The purpose of the present study was to evaluate the outcome of 60 patients at the Virginia Heart Institute with stable angina pectoris, observed between 1976 and 1997, who had documented evidence of severe angiographic disease but were elected to be monitored and managed in an outpatient pharmacologic rehabilitation program. Methods: Sixty patients with significant stenoses by coronary angiography (21 with single-vessel, 26 with double-vessel, and 13 with triple-vessel) without impaired ventricular function, exercise-induced ischemia or hypotension, limited exercise performance, malignant arrhythmias, or drug intolerance were enrolled in a program of pharmacologic rehabilitation and observed for an average of 7.2 years. Results: Among the 60 patients, there were 6 deaths at a mean interval of 8.3 years. Two deaths were in patients ineligible for revascularization. Another patient who died had refused revascularization after new-onset left ventricular dysfunction, and another died intraoperatively during abdominal aortic aneurysm repair. Two patients died while exercising. Thirteen patients underwent follow-up catheterization for worsening angina; 11 of 13 showed progression, predominantly from new lesions. Four of 11 were referred for revascularization; 7 of 11 continued medical treatment; 49 patients were stable on medical therapy throughout the period of observation. Conclusion: Medical management of selected patients with significant coronary stenoses is safe and effective. [source] Dynamics of GH secretion during incremental exercise in obesity, before and after a short period of training at different work-loadsCLINICAL ENDOCRINOLOGY, Issue 4 2010Alberto Salvadori Summary Background, Growth hormone (GH) secretion is normally sensitive to physical exercise. Intensity and duration of exercise, fitness and age can all influence the GH response to exercise. In obesity, GH secretion is decreased both in basal conditions and in response to exercise. Objective, To analyse the dynamics of GH response to a progressive cycloergometric test, conducted up to exhaustion, in adult normal subjects and obese patients, after a reconditioning program at different workloads. Design and methods, We studied eight lean subjects (four men, mean age 34·3 years, range 26,47 years, mean body mass index (BMI) 22·1 kg/m2). GH was sampled at baseline and during the last 30 s of each power output increase. Anaerobic threshold (AT) was detected by the V-slope method. The same test was carried out in 16 obese subjects (seven men, mean age 39·1 years, range 20,59 years, mean BMI 35·8 kg/m2) and repeated after a 4-week reconditioning program consisting of aerobic workout (Group A, eight subjects, three men, mean age 40·5 years, range 22,59 years, mean BMI 33·6 kg/m2), and aerobic plus anaerobic work (group B, eight subjects, four men, mean age 37·6 years, range 20,56 years, mean BMI 38·0 kg/m2) for 6 days/week, with no dietary restrictions. Results, Mean exercise peak occurred at higher intensity in controls (140 vs 110 W, P < 0·05), and AT exceeded at higher work outputs than in obese subjects (102 vs 74 W, P < 0·05). In controls, GH response to exercise was prompt and further sustained after AT; in obese subjects, GH increased slowly and insignificantly before AT, thereafter it increased to lower levels than in controls (P < 0·001). Following the reconditioning period, both Group A and Group B of obese subjects failed to improve exercise performance as well as GH response to exercise before AT; beyond AT, a greater GH response to exercise occurred in Group B than Group A (7·59 ± 0·32 ,g/l at peak of exercise) with significantly different Delta AUCs (Area Under the Curves) following AT: 30·5 ± 12 ,g.min/l in Group A vs 124·2 ± 38 ,g.min/l in Group B, P < 0·05. Conclusions Our results confirm the blunted GH response to exercise in obese adults when compared to lean counterparts. With obesity, aerobic training poorly increases the GH response beyond AT, while supplemental anaerobic workload appears to increase GH response beyond AT. These observations may have implications for the prescription of physical exercise, which is one of the recommendations in the management of obesity. [source] | |||||||||||||||||||||||||