RESUMO
The aim of this study was to assess the value of rigid endoscopy in patients presenting with globus symptoms. We conducted a retrospective analysis of 250 patients who underwent rigid endoscopy for globus symptoms over a 12-month period. In 217 patients (86.8 per cent) the examination of the larynx, pharynx and upper oesophagus was entirely normal. Abnormal findings included cricopharyngeal spasm in 12 patients (4.8 per cent), reflux in 11 (4.4 per cent), pharyngitis in two (0.8 per cent), web in two (0.8 per cent), and retention cyst in three (1.2 per cent). The 95 per cent confidence interval (CI) for the mean number of persons with malignancy based on the Poisson distribution is 0 and 3.7 (0 and 14.8 as rates per 1000). The relationship between the clinical diagnosis and endoscopic findings was examined using the chi-square test, with a p value of 0.0001. These results suggest that patients presenting with globus sensation are unlikely to harbour neoplastic lesions and therefore rigid endoscopy may well be an inappropriate investigation in this group. The risks, costs and discomfort associated with this intervention can often be avoided.
Assuntos
Transtornos de Deglutição/diagnóstico , Endoscopia/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Sulfato de Bário , Transtornos de Deglutição/cirurgia , Esofagoscopia/métodos , Feminino , Humanos , Laringoscopia/métodos , Masculino , Pessoa de Meia-Idade , Cuidados Pós-Operatórios/métodos , Estudos Retrospectivos , Resultado do TratamentoRESUMO
The roles of guanine nucleotide-binding proteins (G-proteins) and cyclic AMP (cAMP) in signal-transduction of inflammatory stimuli leading to arachidonic acid metabolism in resident rat peritoneal macrophages (RPM) were investigated. Opsonized zymosan, targeting multiple receptors and latex particles coated with IgG (latex-IgG), targeting Fc receptors, were used as models of in vivo inflammatory stimuli encountered by macrophages. A comparison of the patterns of eicosanoid products produced in response to these stimuli showed differences: opsonized zymosan stimulated production of more leukotriene B4 (LTB4) than prostaglandin E2 (PGE2), while latex-IgG stimulated production of more PGE2 than LTB4. Non-selective stimulation of G-proteins by GTP and non-hydrolyzable analogs of GTP also stimulated arachidonic acid metabolism; these agents were not selective for PGE2 or LTB4 production. Cholera toxin, however, selectively stimulated production of PGE2 rather than LTB4 and also increased intracellular cAMP concentrations. The increased cAMP did not appear to mediate cholera toxin stimulation since forskolin, which also increased cAMP, was inhibitory to PGE2 production. This suggests that latex-IgG and cholera toxin may activate arachidonic acid metabolism through a G-protein other than Gs to induce PGE2 production specifically. The effects of pertussis toxin were biphasic: a partial inhibitory effect was observed at a low concentration of pertussis toxin (1 ng/ml) on opsonized zymosan or latrix-IgG stimulated arachidonic acid metabolism, while a high concentration of pertussis toxin (100 ng/ml) augmented the stimuli. A pertussis toxin-sensitive G-protein, possibly Gi, may therefore mediate a portion of the stimulatory signals. We have concluded that multiple pathways probably exist for opsonized zymosan and latex-IgG stimulation of arachidonic acid metabolism potentially involving multiple G-proteins.
Assuntos
Ácidos Araquidônicos/metabolismo , Inflamação/fisiopatologia , Macrófagos/fisiologia , Animais , Ácido Araquidônico , Toxina da Cólera/farmacologia , Colforsina/farmacologia , AMP Cíclico/fisiologia , Proteínas de Ligação ao GTP/fisiologia , Guanosina 5'-O-(3-Tiotrifosfato)/farmacologia , Imunoglobulina G/imunologia , Masculino , Cavidade Peritoneal/citologia , Toxina Pertussis , Ratos , Ratos Endogâmicos , Transdução de Sinais , Fatores de Virulência de Bordetella/farmacologia , ZimosanRESUMO
Sarcolemmal vesicles prepared by a new procedure from bovine tracheal smooth muscle were found to have a Na-Ca exchange activity that is significantly higher than that reported for different preparations from other types of smooth muscle. The exchange process system co-purified with 5'-nucleotidase, a plasma membrane marker enzyme, and was significantly enriched (over 100-fold) compared to mitochondria (cytochrome-c oxidase) but only slightly enriched (4-fold) compared to sarcoplasmic reticulum (NADPH-cytochrome-c reductase). The Na+ dependence of Ca2+ transport was demonstrated through both uptake and efflux procedures. The uptake profile with respect to Ca2+ was monotonic with a linear vo VS. vo.S-1 plot. The resultant Km of Ca2+ from the airway sarcolemmal vesicles (20 microM) was similar in magnitude to the Km of cardiac sarcolemmal vesicles (30 microM). Tracheal vesicles demonstrated a Vmax of 0.3-0.5 nmol.mg-1.s-1 which is significantly higher than that reported in preparations from other smooth muscle types. Furthermore, two processes found to stimulate cardiac Na-Ca exchange, pretreatment with either a mixture of dithiothreitol and Fe2+ or with chymotrypsin, were ineffective on the tracheal smooth muscle. Thus, the Na-Ca exchanger identified in tracheal smooth muscle appears to be different from that observed in cardiac muscle, implying that regulation of this activity may also be different.
Assuntos
Cálcio/metabolismo , Músculo Liso/metabolismo , Sarcolema/metabolismo , Sódio/metabolismo , Traqueia/metabolismo , 5'-Nucleotidase , Animais , Transporte Biológico/efeitos dos fármacos , Calcimicina/farmacologia , Bovinos , Fracionamento Celular , Separação Celular , Centrifugação , Ácido Egtázico/farmacologia , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Cinética , Masculino , Mitocôndrias/metabolismo , NADPH-Ferri-Hemoproteína Redutase/metabolismo , Nucleotidases/metabolismo , Cloreto de Potássio/farmacologia , Retículo Sarcoplasmático/metabolismoRESUMO
The effects of thyroid status on the activity of hepatic cAMP phosphodiesterase (PDE) were studied in the rat. Male rats were rendered hyperthyroid by treatment with T3 or hypothyroid by treatment with propylthiouracil. The hepatic particulate low Km PDE was solubilized, and its activity was measured at concentrations of 0.12-1.3 microM cAMP. The Km decreased in hypothyroidism and tended to increase in hyperthyroidism with respect to individual controls. The maximal velocity (Vmax) was unaffected by changes in thyroid status. The increases in Km correlated with increasing plasma T3, whereas the Vmax did not. Concentrations of cAMP increased in the livers from hyperthyroid rats and decreased in those from hypothyroid, in comparison with euthyroid rat livers. The effects of thyroid status on various aspects of hepatic lipid metabolism reported from this laboratory may, in part, have resulted from alterations in hepatic cAMP concentrations. These alterations, may have resulted secondarily from changes in the activity of hepatic PDE by changes in the Km for cAMP with little change in the Vmax.
Assuntos
3',5'-AMP Cíclico Fosfodiesterases/metabolismo , Hipertireoidismo/enzimologia , Hipotireoidismo/enzimologia , Fígado/enzimologia , Animais , AMP Cíclico/metabolismo , Hipertireoidismo/induzido quimicamente , Hipotireoidismo/induzido quimicamente , Cinética , Masculino , Propiltiouracila , Ratos , Ratos Endogâmicos , Tri-Iodotironina/sangueRESUMO
The authors compared two groups of depressed alcoholics given either placebo or chlordiazepoxide-imipramine in a double-blind study. Although depression decreased in both groups, there were no significant differences between them on any of three pre- and posttreament measures. The Zung scale showed that medication decreased depression significantly, however, this finding was not supported by the Beck Depression Inventory or by the Minnesota Multiphasic Personality Inventory, indicating the necessity for use of multiple assessment instruments.
Assuntos
Alcoolismo/complicações , Clordiazepóxido/uso terapêutico , Depressão/tratamento farmacológico , Imipramina/uso terapêutico , Adolescente , Adulto , Alcoolismo/terapia , Aconselhamento , Depressão/diagnóstico , Avaliação de Medicamentos , Quimioterapia Combinada , Casas para Recuperação , Humanos , MMPI , Masculino , Pessoa de Meia-Idade , Psiquiatria Militar , Pacientes Desistentes do Tratamento , Inventário de Personalidade , Placebos , Psicometria , Remissão EspontâneaRESUMO
The authors assessed by questionnaire the alcohol use of 1,873 U.S. soldiers in the United States and Viet Nam. According to operational definitions based on total ethyl alcohol consumption and several behaviors associated with drinking, 7 percent were classed as alcoholics, 5 percent as borderline alcoholics, and 24 percent as potential alcoholics. Contrary to popular stereotypes, there was a disproportionate number of younger and lower ranking soldiers in these three groups; there was also a positive relationship between drinking and use of illicit drugs across groups. The authors state that future studies of alcohol use should include determinations of total ethyl alcohol intake to permit generalizability of their results.
Assuntos
Consumo de Bebidas Alcoólicas , Militares/psicologia , Adolescente , Adulto , Alcoolismo/epidemiologia , Família , Humanos , Drogas Ilícitas/administração & dosagem , Masculino , Estados Unidos , VietnãRESUMO
Studies conducted with the goal of discovering a second-generation platelet-activating factor (PAF) antagonist have identified a novel class of potent and orally active antagonists which have high aqueous solubility and long duration of action in animal models. The compounds arose from the combination of the lipophilic indole portion of Abbott's first-generation PAF antagonist ABT-299 (2) with the methylimidazopyridine heterocycle moiety of British Biotechnology's BB-882 (1) and possess the positive attributes of both of these clinical candidates. Structure-activity relationship (SAR) studies indicated that modification of the indole and benzoyl spacer of lead compound 7b gave analogues that were more potent, longer-lived, and bioavailable and resulted in the identification of 1-(N, N-dimethylcarbamoyl)-4-ethynyl-3-[3-fluoro-4-[(1H-2-methylimidazo[4,5-c] pyrid-1-yl)methyl]benzoyl]indole hydrochloride (ABT-491, 22 m.HCl) which has been evaluated extensively and is currently in clinical development.
Assuntos
Imidazóis/síntese química , Fator de Ativação de Plaquetas/antagonistas & inibidores , Inibidores da Agregação Plaquetária/síntese química , Glicoproteínas da Membrana de Plaquetas/metabolismo , Piridinas/síntese química , Receptores de Superfície Celular , Receptores Acoplados a Proteínas G , Animais , Disponibilidade Biológica , Plaquetas/efeitos dos fármacos , Plaquetas/fisiologia , Permeabilidade Capilar/efeitos dos fármacos , Cães , Feminino , Cobaias , Humanos , Imidazóis/química , Imidazóis/farmacologia , Macaca fascicularis , Masculino , Estrutura Molecular , Fator de Ativação de Plaquetas/farmacologia , Inibidores da Agregação Plaquetária/química , Inibidores da Agregação Plaquetária/farmacocinética , Inibidores da Agregação Plaquetária/farmacologia , Piridinas/química , Piridinas/farmacocinética , Piridinas/farmacologia , Ratos , Ratos Sprague-Dawley , Relação Estrutura-AtividadeRESUMO
The monocytic cell line THP-1 can be induced to express and release tumor necrosis factor alpha (TNFalpha) and both TNFalpha receptors (p55 and p75) upon exposure to bacterial lipopolysaccharide (LPS). The broad-spectrum matrix metalloprotease (MMP) inhibitors [4-(N-hydroxyamino)-2R-isobutyl-3S-(phenylthiomethyl)succinyl]-L-p henylalanine-N-methylamide (GI-129471) and marimastat [2S-[N4(R*),2R*,3S*]]-N4[2,2-dimethyl-1-[(methylamino)carbonyl]propyl]-N 1,2-dihydroxy-3-(2-methylpropyl)butanediamide (BB-2516) were effective inhibitors of LPS-induced TNFalpha (soluble) release with IC50 values of 0.2 and 4.0 microM, respectively. Upon LPS stimulation, the expression of pro-TNFalpha (membrane associated) on the cell surface (FACS analysis) could not be observed. However, in the presence of GI-129471, a concentration-dependent increase in TNFalpha surface expression was observed. Peak expression (percentage of cells expressing pro-TNFalpha and mean fluorescence units) in the presence of GI-129471 was at 2 hr, and steadily declined to return to near control levels by 8 hr. This time course was similar to TNFalpha release, which also peaked at 2-4 hr after LPS exposure and then declined. Stimulation of THP-1 cells with LPS + phorbol myristate acetate increased the percentage of cells expressing pro-TNFalpha by 10-fold. In the presence of GI-129471, these increases were augmented further and peaked between 2 and 4 hr, but also returned to near control levels of expression by 24 hr. This was in contrast to the release of soluble TNFalpha, which continued to accumulate over a 24-hr time course. TNFalpha receptor I (p55, TNFRI) and II (p75, TNFRII) shedding was also inhibited by GI-129471 (IC50 = 1.5 and 3.1 microM, respectively) and BB-2516 (IC50 = 14 and 15 microM, respectively). Unlike pro-TNFalpha surface expression, surface expression of both TNFalpha receptors steadily increased over 72 hr. In contrast to pro-TNFalpha surface expression, TNFRI surface expression was not augmented by these MMP inhibitors in THP-1 cells after LPS stimulation. Surface expression of TNFRII was augmented by these MMP inhibitors. These results suggest that even in the continued presence of LPS stimulation and an inhibitor of TNFalpha processing, the augmented surface expression of TNFalpha is transient. The potential "deleterious" implications of high levels of surface pro-TNFalpha expression in the presence of these inhibitors may be lessened by its transient nature.
Assuntos
Metaloendopeptidases/antagonistas & inibidores , Monócitos/efeitos dos fármacos , Fator de Necrose Tumoral alfa/biossíntese , Linhagem Celular , Membrana Celular/metabolismo , Citocinas/biossíntese , Humanos , Lipopolissacarídeos/farmacologia , Monócitos/metabolismo , Acetato de Tetradecanoilforbol/farmacologiaRESUMO
To determine any overlap in pathological features between myoepithelial sialadenitis and chronic sialadenitis/sialolithiasis histological sections from 69 cases of myoepithelial sialadenitis (MESA) (n = 7) and chronic sialadenitis/sialolithiasis (n = 62) were reviewed over a 10 year period. Three of the cases with MESA contained calculi and four of those originally diagnosed as chronic sialadenitis/sialolithiasis showed epimyoepithelial island formation. The presence of calculi should not rule out a diagnosis of MESA, particularly in the parotid gland where calculi are uncommon; as the incidence of MESA may very well be underestimated and diagnosed as chronic sialadenitis, these patients, who are at increased risk of developing lymphoma, could be lost to follow up.
Assuntos
Cálculos dos Ductos Salivares/patologia , Doenças das Glândulas Salivares/patologia , Sialadenite/patologia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Glândula Parótida/patologia , Cálculos dos Ductos Salivares/complicações , Sialadenite/complicações , Glândula Submandibular/patologiaRESUMO
New information has challenged our traditional concepts that the forms and functions of PLA(2) are highly homologous, suggesting now that distinct PLA(2)s may be assigned distinct functions in normal and pathological processes. The nonpancreatic type II 14-kDa PLA(2) and the recently identified type IV "cytosolic" 85-kDa PLA(2) are the two forms most studied in inflammation. Observations in the past suggested that the type II 14-kDa PLA2 is a secreted enzyme that functions extracellularly. Evidence is now emerging that the type II 14-kDa PLA(2) or its recently discovered low-molecular-weight isoforms may be localized and act intracellularly. In view of this, a more complex notion of distinctly functioning PLA(2)s in arachidonic acid release and/or eicosanoid generation can be envisioned. A comparison of the structural and biochemical features of the type II 14-kDa and the 85-kDa PLA(2)s reveals that the enzymes are more distinct than similar. These two enzymes would appear to have distinctly different genetic and biochemical regulatory mechanisms, suggesting that their functions could be quite distinct. Inhibitors of the 14-kDa PLA(2) and to a lesser extent the 85-kDa PLA(2) have been used to obtain a greater understanding of their cellular roles. The concept that the two distinct enzymes might hydrolyze arachidonic acid from different pools and/or supply distinct metabolizing systems in a single cell system has emerged. At this time an intriguing hypothesis can be formed suggesting distinct functional modalities for the two the PLA(2) enzymes in a single cell system. Evidence continues to build implicating the role of the type II 14-kDa PLA(2) in disease, providing a strong rationale for targeting this enzyme in designing novel antiinflammatory therapeutics.
RESUMO
The rat paw edema-inducing, acute inflammatory activity of four snake venom phospholipase A2S (PLA2) (Naja naja, Naja mocambique mocambique, Crotalus atrox and recombinant Naja naja naja) and of recombinant human type II PLA2 (rh-PLA2) found in rheumatoid synovial fluid, were compared after a bolus subplantar injection. The snake venom-derived PLA2s, including the recombinant Naja naja naja, were potent inducers of paw edema. On the other hand, when given in similar amounts (protein and/or enzymatic activity), the rh-PLA2 did not produce paw edema. Furthermore, the addition of Naja naja PLA2, blood plasma from rats with adjuvant arthritis or the E. coli-based enzymatic incubation mixture used to measure PLA2 activity to the injection mixture containing rh-PLA2, did not result in paw edema-inducing activity. These results suggest that the lack of paw edema-inducing activity of rh-PLA2 may be due to significant structural differences between snake venom PLA2s and human PLA2 which allow snake venom PLA2s, but not the human group II PLA2, to express inflammatory activity as measured by paw edema in rat induced by a bolus injection.
Assuntos
Edema/induzido quimicamente , Inflamação/induzido quimicamente , Fosfolipases A/toxicidade , Animais , Artrite Experimental/enzimologia , Venenos de Crotalídeos/enzimologia , Venenos Elapídicos/enzimologia , Humanos , Masculino , Fosfolipases A/química , Fosfolipases A/isolamento & purificação , Fosfolipases A2 , Ratos , Ratos Endogâmicos Lew , Proteínas Recombinantes/toxicidade , Líquido Sinovial/enzimologiaRESUMO
The aim of the present work was to elucidate the role of cytosolic calcium ions, [Ca2+]i, in the control of arachidonic acid release and metabolism. [Ca2+]i was measured in resident peritoneal rat macrophages loaded with Fura2, and compared with the release of leukotriene B4(LTB4) and prostaglandin l2 (PGL2, assayed through its hydrolysis product 6-keto-PGF1 alpha). The calcium ionophore A 23187 stimulated both an increase in [Ca2+]i and the release of LTB4 and 6-keto-PGF1 alpha. On the contrary, zymosan and opsonized zymosan, while stimulating eicosanoid release to an extent only slightly lower than A 23187, did not affect [Ca2+]i. Lipopolysaccharide stimulated 6-keto-PGF1 alpha, but not LTB4, release, without affecting [Ca2+]i. In parallel experiments, macrophages were prelabelled with [3H]arachidonic acid and the release of total 3H-products was assayed and taken as an index of phospholipase activity. A 23187, zymosan and opsonized zymosan increased the release of 3H-products in the presence of Ca2+. When extracellular Ca2+ was removed, the ionophore-induced 3H-products release was greatly blunted, while the release induced by zymosan was actually augmented. Our data indicate that a generalized [Ca2+]i increase is not necessary for arachidonic acid release and metabolism in rat peritoneal macrophages.
Assuntos
Ácidos Araquidônicos/metabolismo , Cálcio/metabolismo , Citosol/metabolismo , Macrófagos/metabolismo , Animais , Ácido Araquidônico , Calcimicina/farmacologia , Ácidos Eicosanoicos/metabolismo , Epoprostenol/metabolismo , Fura-2 , Técnicas In Vitro , L-Lactato Desidrogenase/metabolismo , Leucotrieno B4/metabolismo , Lipopolissacarídeos/farmacologia , Masculino , Microquímica , Fagocitose/efeitos dos fármacos , Fosfolipases A/metabolismo , Ratos , Ratos Endogâmicos , Espectrometria de Fluorescência , Zimosan/farmacologiaRESUMO
ABT-491 (4-ethynyl-N, N-dimethyl-3-[3-fluoro-4-[(2-methyl-1H-imidazo-[4,5-c]pyridin-1-yl)methy l]benzoyl]-1H- indole-1-carboxamide hydrochloride) is a novel PAF (platelet-activating factor) receptor antagonist with a K(i) for inhibiting PAF binding to human platelets of 0.6 nM. Binding kinetics of ABT-491 to the PAF receptor is consistent with a relatively slow off-rate of the antagonist when compared to PAF. Inhibition of PAF binding is selective and is correlated with functional antagonism of PAF-mediated cellular responses (Ca2+ mobilization, priming, and degranulation). Administration of ABT-491 in vivo leads to potent inhibition of PAF-induced inflammatory responses (increased vascular permeability, hypotension, and edema) and PAF-induced lethality. Oral potency (ED50) was between 0.03 and 0.4 mg/kg in rat, mouse, and guinea-pig. When administered intravenously in these species, ABT-491 exhibited ED50 values between 0.005 and 0.016 mg/kg. An oral dose of 0.5 mg/kg in rat provided > 50% protection for 8 h against cutaneous PAF challenge. ABT-491 administered orally was also effective in inhibiting lipopolysaccharide-induced hypotension (ED50 = 0.04 mg/kg), gastrointestinal damage (0.05 mg/kg, 79% inhibition), and lethality (1 mg/kg, 85% vs. 57% survival). The potency of this novel antagonist suggests that ABT-491 will be useful in the treatment of PAF-mediated diseases.
Assuntos
Imidazóis/farmacologia , Indóis/farmacologia , Glicoproteínas da Membrana de Plaquetas/antagonistas & inibidores , Receptores de Superfície Celular , Receptores Acoplados a Proteínas G , Doença Aguda , Animais , Plaquetas/efeitos dos fármacos , Relação Dose-Resposta a Droga , Endotoxemia/tratamento farmacológico , Cobaias , Humanos , Inflamação/induzido quimicamente , Inflamação/tratamento farmacológico , Lipopolissacarídeos/toxicidade , Masculino , Camundongos , Camundongos Endogâmicos ICR , Neutrófilos/efeitos dos fármacos , Fator de Ativação de Plaquetas/antagonistas & inibidores , Fator de Ativação de Plaquetas/efeitos dos fármacos , Fator de Ativação de Plaquetas/metabolismo , Glicoproteínas da Membrana de Plaquetas/metabolismo , Coelhos , Ratos , Choque/induzido quimicamente , Choque/tratamento farmacológicoRESUMO
Running economy, defined as the steady-state VO2 for a given running velocity, has been shown to account for a large and significant proportion of variation in distance-running performance among runners roughly comparable in VO2 max. Despite this recognition, relatively little is known regarding the potpourri of physiological, environmental, structural and mechanical factors potentially associated with a lower aerobic demand of running. Early attempts at quantifying the energy expenditure of exhaustive runs incorporated measurements of oxygen consumption before, during, and after exercise. The validity of this approach has been questioned, however, since recent evidence has demonstrated that only a moderate relationship exists between postexercise VO2 and anaerobic metabolism. The energy demands for submaximal running (i.e. running economy) can be quantified by calculating the steady-state VO2, expressed with respect to body mass and time, for a standardised, submaximal running speed. Since this variable represents the aerobic demand of running, the generation of energy must derive wholly from cell respiration and not from substantial protein catabolism. Research has indicated that at low to moderate work rates, the steady-state energy condition is attained in about 3 minutes. Trained individuals reach steady-state sooner than unfit subjects. While limited by methodological constraints, the existence of a steady-state has also been verified by the lack of blood lactate accumulation and the presence of a respiratory exchange ratio of less than 1.00. The ability of economy, either singly or in combination with VO2 max, to account for a substantial portion of performance variation among trained distance runners and untrained subjects of comparable ability and fitness level has been demonstrated in recent cross-sectional studies. Limited data from short and long term longitudinal research also suggests that endurance running success is linked to training and growth-related improvements in economy. Intraindividual variation in economy has been shown to vary between 2% and 11% for a given speed. Most of this variation can probably be attributed to biological error. While the majority of evidence does not support a gender difference in running economy, data from some studies suggest that males may be more economical than women. Prepubescent children are less economical than older children and adults, whereas older adults exhibit the same trend when compared to younger counterparts. Because of air and wind resistance, the aerobic demands of indoor treadmill running significantly underestimate the cost of overground running, especially at higher speeds.(ABSTRACT TRUNCATED AT 400 WORDS)
Assuntos
Corrida , Fenômenos Biomecânicos , Feminino , Humanos , Masculino , Consumo de OxigênioRESUMO
This symposium endeavors to address the issue of running economy from a multidisciplinary perspective. Topics addressed in this symposium include physiological aspects of running economy, changes in running economy with age during childhood and adolescence, biomechanical considerations for economical walking and running, psychological state and running economy, and running economy of elite performers. While the knowledge base in this area is expanding, future research should emphasize the formulation of testable hypotheses and the fostering of collaborative efforts aimed at identifying and manipulating variables associated with improved economy and discovering mechanisms underlying economical running styles.
Assuntos
Esforço Físico/fisiologia , Corrida , HumanosRESUMO
PURPOSE: To determine whether there is a significant relationship between accumulated oxygen deficit (AOD) and 800-m running performance in a group of runners of homogeneous ability. METHODS: Nine well-trained male middle and long distance runners (age = 24.7 +/- 4.5 yr, body mass = 69.4 +/- 8.5 kg, VO2max = 64.8 +/- 4.5 mL.kg-1.min-1) underwent treadmill testing to determine maximum oxygen uptake (VO2max), running economy (RE) at 1% and 10.5% treadmill gradient, and AOD at 1% and 10.5% treadmill gradient; 800-m running performance was determined by time trials on an outdoor 440-yd track, for which the average time was 132 +/- 4 s. For the AOD test, subjects were required to run on the treadmill at supramaximal speeds until volitional exhaustion. The AOD value was calculated using linear (LIN) and curvilinear (CUR) extrapolation procedures. RESULTS: Mean AOD values using LIN and CUR were 45.0 +/- 6.9 and 59.3 +/- 10.1 mL.kg-1 at a 1% treadmill gradient and 63.2 +/- 10.6 and 93.6 +/- 19.7 mL.kg-1 at a 10.5% gradient, respectively. No significant relationship was found between 800-m run time and AOD at 1% gradient or 10.5% gradient or when AOD was estimated from a linear or curvilinear fit of the VO2 data. Other variables measured in this study (e.g., VO2max and running economy) were not found to be predictive of 800-m run time. CONCLUSION: Among a homogeneous group of well-trained male middle- and long-distance runners, AOD measured at a 1% and 10.5% treadmill gradient is not significantly related to 800-m running performance.
Assuntos
Consumo de Oxigênio/fisiologia , Corrida/fisiologia , Adolescente , Adulto , Dióxido de Carbono/análise , Teste de Esforço , Tolerância ao Exercício/fisiologia , Previsões , Frequência Cardíaca/fisiologia , Humanos , Modelos Lineares , Masculino , Destreza Motora/fisiologia , Oxigênio/análise , Resistência Física/fisiologia , Fatores de TempoRESUMO
The study of running economy has important performance implications for the long-distance runner and may provide insight into mechanisms underlying economical human locomotion. Physiological aspects of running economy discussed in this paper include intraindividual variability, body temperature, heart rate, ventilation, muscle fiber type, gender, air and wind resistance, altitude, fatigue, and training. The lack of consensus evident in the literature regarding many of these variables and their influence on economy supports the use of expanded sample sizes featuring both genders, standard testing conditions, and cross- and interdisciplinary approaches to help explain group economy differences observed in descriptive and experimental paradigms and to extend the generalizability of research findings.
Assuntos
Consumo de Oxigênio , Esforço Físico/fisiologia , Corrida , Altitude , Temperatura Corporal/fisiologia , Fadiga , Frequência Cardíaca/fisiologia , Humanos , Músculos/metabolismo , Resistência Física , Fatores SexuaisRESUMO
It has been suggested that biomechanical factors play a role in explaining interindividual differences in movement economy, but it is not apparent how important this role is nor how consistently these factors explain such differences. The purpose of this review is to summarize our current state of knowledge regarding the relationships between gait economy and selected body structure and biomechanical factors. Because the research literature contains other review papers on this general topic, it is not the intent to provide a comprehensive analysis of all anatomical and biomechanical factors that have been examined previously. The review considers not only some topics of very recent interest (e.g., Does flexibility/joint range of motion affect gait economy? Can gait mechanics and economy be altered effectively via biomechanical feedback?), but also topics that have been examined considerably over many years (e.g., Is economy of motion associated with body mass, mass distribution, speed of movement, stride length and rate, and gait kinetics?). Results from the many studies reviewed confirm the notion that several structural and biomechanical factors offer some potential for explaining economy differences between individuals. Nevertheless, the relationships that have been observed between economy and individual descriptors of body structural and gait mechanics have generally been weak and inconsistent from study to study. Variables that describe muscular effort appear to have the greatest potential for explaining metabolic energy demands during walking and running. Unfortunately, at present it is unclear what quantifiable descriptors can best reflect muscle force production.
Assuntos
Marcha , Corrida , Caminhada , Fenômenos Biomecânicos , Constituição Corporal , Metabolismo Energético , Retroalimentação , Marcha/fisiologia , Humanos , Consumo de Oxigênio , Amplitude de Movimento Articular/fisiologiaRESUMO
The objectives of this study were to: (a) develop a physiological profile for a group of trained triathletes and (b) determine whether multiple modes of training result in general or specific adaptations. VO2max of 13 trained triathletes (mean = 29.5 yr) was measured during treadmill running (TR), cycle ergometry (CE), and tethered swimming (TS) over a 6-wk period encompassing a half-triathlon (1.2 mile swim/56 mile bike/13.1 mile run). Most subjects performed two tests in each mode. Since test-retest reliability coefficients for TR, CE, and TS VO2max were 0.97, 0.93, and 0.97, respectively, results were averaged: formula; see text The mean TR VO2max indicated that the subjects were well-trained, but not of elite caliber. Mean CE VO2max was 95.7% of the TR value, which is greater than the value typically found in non-cyclists (88 to 92%) but less than that of highly trained cyclists (98 to 105%). Mean TS VO2max was 86.6% of the TR value. As in cyclists, this percentage is greater than that of recreational swimmers (78 to 82%) but less than that of elite swimmers (93 to 95%). Running and cycling times in the triathlon were significantly (P less than 0.01) related to the corresponding VO2max values (r = -0.68 and r = -0.78, respectively), but swimming times were not (r = -0.50). It is concluded that these triathletes were well-trained in all events, but not to the same extent as athletes who train in only one sport. Running and cycling performance were associated with VO2max.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Ciclismo , Consumo de Oxigênio , Educação Física e Treinamento/métodos , Corrida , Esportes , Natação , Adulto , Frequência Cardíaca , Humanos , Masculino , Troca Gasosa Pulmonar , RespiraçãoRESUMO
The purpose of this study was to determine the relationship between psychological states as measured by the Profile of Mood States (POMS) inventory and within-subject variation in running economy (RE) in moderately trained male runners (N = 10). Subjects (ages 20-34 yr) were monitored during treadmill running, five times a week (Monday through Friday) for 4 wk, at 2.68, 3.13, and 3.58 m, s-1. Tension, depression, anger, vigor, fatigue, confusion, and a total mood disturbance (TMD) score were assessed every Friday prior to the treadmill running sessions. Oxygen consumption (VO2) was determined via the open-circuit method during each of the three running paces. VO2 values were averaged over 5 d and three speeds for each week (RE) and were correlated with the weekly TMD scores, resulting in a nonsignificant group correlation of r = -0.28. The within-subject group correlation between TMD scores and RE was r = 0.88. This positive correlation indicates that, when the focus of attention was on within-subject variation, weeks featuring more economical values were associated with more positive mental health profiles. Correlations between average VO2 and the six POMS subscales were tension. r = 0.81; depression, r = 0.73; anger, r = 0.58; vigor, r = -0.60: fatigue, r = 0.18; and confusion, r = 0.60. All correlation coefficients except for fatigue were significantly (P less than 0.01) related to average VO2. In conclusion, it appears that short-term fluctuations in RE of moderately trained male runners are closely tied to their mood state.