ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

CARTER, R., J. R. COAST, and S. IDELL. Exercise training in patients with chronic obstructive pulmonary disease.Med. Sci. Sports Exerc., Vol. 24, No. 3, pp. 281–291, 1992. Most patients with chronic obstructive pulmonary disease (COPD) demonstrate positive responses to exercise conditioning. Dyspnea is reduced and work tolerance is extended with little or no change in pulmonary function noted. Possible explanations for the increased ability to better tolerate exercise and activities of daily living (ADL) after training include: 1) psychological encouragement, 2) improvements in mechanical efficiency, 3) improved cardiovascular conditioning, 4) improved muscle function, 5) biochemical adaptations responsible for reducing glucose utilization, 6) desensitization to dyspnea, and 7) contributions from better self-care. However, not all patients respond positively to exercise conditioning. This may represent differences in patient selection, training approaches, and/or comorbidity issues commonly seen in patients with COPD. Alternatively, the answer may reside in devising an optimal training intensity, duration, and frequency combination for patients with COPD. This is not an easy matter because of the diversity of patients categorized as COPD. We have reviewed these issues from the available data and presented areas where additional research is warranted. What is needed at present is a series of well-controlled studies that focus on identifying and improving training responses in patients with COPD. Secondary to this issue is the long term epidemiologic surveillance of trained patients to document sustained effects.

ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

KANNUS, P. and K. YASUDA. Value of isokinetic angle-specific torque measurements in normal and injured knees.Med. Sci. Sports Exerc., Vol. 24, No. 3, pp. 292–297, 1992. This study assessed the relationship between the isokinetic peak torque (PT) (speed of movement 60 and 180 degrees · s-1) and the angle-specific torques (ASTs) at 15 and 75 degrees of knee flexion in multiple contractions of the quadriceps and hamstrings in 80 subjects with a grade I knee injury. At every test speed, the Pearson product moment (r) and the Spearman rank (rs) correlation coefficients between the PT and ASTs were highly significant (P< 0.001) for both muscle groups in the uninjured (r= 0.73–0.88, rs= 0.75–0.89) as well as in the injured (r= 0.63–0.91, rs= 0.65–0.91) knees. In both extremities, a great majority of the correlation coefficients exceeded 0.80, which was the predetermined threshold for the coefficients to exceed before the relationship could be considered clinically important. Using regression analysis, both extremities showed completely nonsystematic distribution of the residuals. The variability of the AST measurements was clearly higher than corresponding PT measurements. In conclusion, concerning healthy or grade I injured knees, the predictability of ASTs from PT was good; and, therefore, AST analyses offer little additional information about thigh muscle function than that obtained through the simpler and more commonly used measurement, PT analysis. Because of large variability, the routine use of the AST measurements for grade I knee injuries is not recommended.

ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

LEGROS, P., P. JEHENSON, J. P. GASCARD, G. KOZAK-REISS. Long-term relationship between acute rhabdomyolysis and abnormal high-energy phosphate metabolism potentiated by ischemic exercise.Med Sci. Sports Exerc., Vol. 24, No. 3, pp. 298–302, 1992. Relative concentrations of inorganic phosphate [Pi]r, creatine phosphate [CP]r, adenosine triphosphate [ATP]r, and intracellular pH (pHi) were determined by31P-NMR spectroscopy in the flexores digitorum muscles. The measurements were performed at rest, during bouts of rhythmic exercises at different powers, including one with restricted blood supply, and during recovery. Normal subjects (N) and subjects with previous histories of exercise hyperthermia (EH) were compared. No significant difference was found between N and EH subjects at rest. During exercise [ATP]rwas not affected, except in EH subjects exercising under partial muscle ischemia (P< 0.001); in both N and EH, [CP]rand pHj decreased, and the higher the load the more pronounced the reduction. These changes were significantly larger in EH patients than in N (P< 0.05), and the differences were dramatically increased by reducing blood supply (P< 0.001). During recovery, the return to the control values was much slower in EH patients than in N, in particular for pHi after the exercise under partial ischemia. In conclusion, the fact that metabolic disorders are still patent long after the EH occurrence supports the possibility of latent myopathy and of a persistent metabolic disorder. Thus,31P-NMR spectroscopy could be a useful noninvasive test to detect EH susceptibility in at-risk subjects.

ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

KENNEY, W. L. and J. M. JOHNSON. Control of skin blood How during exercise.Med. Sci. Sports. Exerc., Vol. 24, No. 3, pp. 303–312, 1992. When body temperature rises, skin blood flow (SkBF) increases to effect transfer of metabolic heat from the core to the skin. This convective heat transfer is never more important than during dynamic exercise. Control of SkBF involves a complex interaction of regulatory systems (body temperature, blood pressure, metabolism, etc.) and efferent mechanisms (passive withdrawal of constrictor tone, reflex vasoconstriction, active vasodilation). The purpose of this paper is to provide an updated review of this complex control system—control that allows for maintenance of blood pressure and perfusion of active muscle without adverse impact on thermoregulation. Also discussed are vasomotor mechanisms, various components of exercise that are important in the control of SkBF (e.g., intensity, posture, and duration of exercise), and the influences of such factors as blood volume and tonicity, aerobic fitness and heat acclimation, and age.

ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

FALK, B., O. BAR-OR, R. CALVERT, and J. D. MACDOUGALL. Sweat gland response to exercise in the heat among pre-, mid-, and late-pubertal boys.Med. Sci. Sports Exerc., Vol. 24, No. 3, pp. 313–319, 1992. Sweating rate (SR) of boys is lower than that of men. To assess the association between the response of individual sweat glands and physical growth and maturation, three groups of circumpubertal boys cycled at 50% &OV0312;O2maxin a climatic chamber (42°C, 20% relative humidity). Based on Tanner staging (pubic hair), 16 were classified as prepubertal (PP, Tanner 1), 15 as midpubertal (MP, Tanner 2–4), and five as late-pubertal (LP, Tanner 5). Population density (PD) of the heat-activated sweat glands, the mean area of sweat drops (DA), and the proportion of skin covered by sweat (%A) were measured by skin photography and computer-assisted imaging analysis. Other measurements included rectal and skin temperatures (Tre, Tsk, respectively), heart rate (HR), and total body SR. The rise in HR, Treand Tskdid not differ among groups. Whole body SR was significantly higher in the LP group compared with PP (PP = 4.95 ± 0.23, MP = 5.79 ± 0.20, LP = 6.70 ± 0.42 ml · min-1· m-2) (mean ± SEM). PD was significantly higher in the PP group (PP = 128 ± 8, MP = 97 ± 9, LP = 74 ± 9 glands · cm-2), while DA was higher in the LP group (PP = 5.47 ± 0.59, MP = 6.92 ± 0.47, LP = 12.83 ± 1.41 ·m2· 104). A did not differ among groups. The calculated SR per gland was higher among the LP groups compared with the less mature ones (PP = 4.6 ± 0.3, MP = 7.2 ± 0.8, LP = 9.6 ± 1.0 nl · min-1). SR per gland was inversely related to PD (r= −0.88), and positively related to DA (r =0.67), but was not related to %A (r= −0.08). We conclude that physical growth and maturation are accompanied by decreased density of heat-activated sweat glands, but an increased sweat drop area. This is reflected by an increased SR per gland.

ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

JARVIS, J. K., D. PEARSALL, C. M. OLINER, and D. A. SCHOELLER. The effect of food matrix on carbohydrate utilization during moderate exercise.Med. Sci. Sports Exerc., Vol. 24, No. 3, pp. 320–326, 1992. To determine the effect of food type and form on the rate of assimilation and utilization of a meal given before exercise, five physically active adult males walked for 4 h on a 10% uphill graded treadmill at 40% &OV0312;O2max. After a 12-h fast, and 30 min before exercise, subjects ingested 70 g of liquid glucose (G), a refined “hot cereal” (R), a refined “hot cereal” with water-soluble fiber (R/F), an oat bar (O), or placebo (P). Meals R/F, R, and O had significantly lower (P< 0.05) peak plasma glucose responses than meal G (0.8, 0.9, 1.0, and 2.4 mmol ·1-1, respectively). Meals R, O, and R/F had significantly lower (P< 0.01) peak insulin responses than meal G (135, 150, 190, and 340 pmol ·1-1, respectively). All meals except P contained an extrinsic tracer of 200 mg UL-13C-glucose. Mean (±SD) total recovery of the administered dose of13C for all meals was 81 ± 2%. Both O (34 ± 4% dose · h-1) and R/F (30 ± 3% dose-h-1) had significantly lower peak recoveries than did meal G (41 ± 5% dose · h-1). Meal R/F had a significantly lower (P< 0.05) rate of exogenous glucose oxidation than meal G during the first hour of exercise. These data suggest that meal R/F slows the rate of assimilation and utilization of exogenous glucose, but does not alter the cumulative 4-h utilization.

ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

EL-SAYED, M. S. Extrinsic plasminogen activator response to exercise after a single dose of propranolol.Med. Sci. Sports Exerc., Vol. 24, No. 3, pp. 327–332, 1992. The level of plasminogen activators was measured in 12 volunteers at rest and after maximum exercise. Two formulations of a beta-blocker “propranolol,” or placebo, were given (oral dose, 10 mg) 2 h before exercise commenced. At weekly intervals over 21 d, randomized double-blind, cross-over trials were conducted. Two hours after drug/placebo administration, subjects exercised to maximal capacity using an incremental exercise protocol on a bicycle ergometer. Before and 2 h after drug/placebo administration and immediately after maximum exercise, heart rate, blood pressure, and oxygen consumption were measured, venous blood was removed, and plasma separated for the measurement of plasminogen activators using the fibrin plate method. Duplicate portions of plasma were taken: portion 1 for determination of total plasminogen activators activity, by the addition of dextran sulphate and flufenamic acid; portion 2 to assay extrinsic plasminogen activator, intrinsic plasminogen activator being blocked by the addition of C1-inactivator. Resting and postmaximum exercise heart rates showed significant decreases (P< 0.05), with a nonsignificant difference in the resting level of extrinsic and intrinsic activators when the subjects were premedicated with either of the two formulations. Total and extrinsic activities, but not intrinsic activity, were significantly increased (P< 0.05) to maximum exercise when subjects were given placebo. However, premedication with the drug formulations 1 and 2 significantly decreased (P< 0.05) the normal total and extrinsic activities response to maximum exercise, with no effect on the intrinsic activity. It is suggested that the resting level of activators activity may not be affected by premedication with propranolol. After maximum exercise without medication (placebo), there was an increase in total plasminogen activator mainly due to an increase in extrinsic plasminogen activator, but with medication only extrinsic plasminogen activator response was decreased, and therefore this response may be beta-adrenergically mediated.

ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

WEYRICH, A. S., W. J. REJESKI, P. H. BRUBAKER, and J. S. PARKS. The effects of testosterone on lipids and eicosanoids in cynomolgus monkeys.Med. Sci. Sports Exerc., Vol. 24, No. 3, pp. 333–338, 1992. The effect of testosterone administration on plasma lipoproteins and eicosanoids was studied in 24 male cynomolgus monkeys. We hypothesized that elevated plasma testosterone would unfavorably alter plasma lipids as well as thromboxane A2(TxA2) and prostacyclin (PGI2), two eicosanoids that have been linked to the increased incidence of atherosclerosis, myocardial ischemia, and thrombosis. To test our hypothesis, half of the monkeys (N =12) were subjected to 10 wk of testosterone treatment, whereas the remaining monkeys (N= 12) received a sesame oil vehicle. The plasma concentrations of thromboxane B2(TxB2) and 6-keto-PGFIalpha, the stable metabolites of TxA2and PGI2, respectively, were determined. Additionally, assays were conducted on total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), and triglycerides (TG). Distribution of the HDL subfraction protein was measured by gradient gel electrophoresis. All monkeys exhibited significant increases in TC (P< 0.001) and low density lipoprotein cholesterol (LDL-C) (P< 0.001); however, monkeys who received testosterone also displayed significant increases in TxB2(P< 0.03) and decreases in HDL-C (P< 0.03) compared with control monkeys. There was a trend in the HDL-C subfraction data, indicating that testosterone treatment may be associated with a decrease in the larger HDL2bsubfraction and a corresponding increase in HDL3c. These results demonstrate that exogenous testosterone adversely alters cardiovascular risk profiles by increasing TXB2production and decreasing HDL-C. Athletes who use testosterone as an anabolic androgenic steroid may have an increased risk for coronary heart disease.

ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

FRY, R. W., A. R. MORTON, and D. KEAST. Acute intensive interval training and T-lymphocyte function.Med. Sci. Sports Exerc., Vol. 24, No. 3, pp. 339–345, 1992. Immune suppression has been suggested to occur as a result of acute exercise although results of previous studies are variable, possibly due to the failure of some researchers to control exercise intensity and duration. Most of the studies so far have investigated immediate effects after bouts of exercise mainly in subjects undertaking lower body exercise (running or cycling), and the time course of recovery has rarely been determined. We chose two groups of athletes for our studies. One group represented subjects of a range of fitness levels from recreational runners to high-performance runners. The second group represented kayakists with a similar range of fitness levels. Following interval training designed to stress either the lower or upper body anaerobically, we have now shown that upper body exercise (kayaking) induces similarin vitroresponses to those described for lower body exercise. There were no differences between the responses of low-fitness versus high-fitness subjects. In addition we have studied thein vitroresponses of leukocytes following acute anaerobic exercise over a 24-h recovery period. The results showed that the reduced lymphocyte proliferative response,in vitro, to the T-cell mitogen CONA experienced immediately after exercise returned to normal levels within 2 h of recovery time. This suggests that the reduction in lymphocyte proliferative response is a short transient one. The addition of interleukin-2 (IL-2) or indomethacin to the mitogen-stimulated cultures of preexercise and postexercise cells demonstrated that the postexercise suppression in3H-DNA synthesis of the leukocytes could not be accounted for by either an inability of the T-cells to produce IL-2 or the inhibitory action of prostaglandin production.

ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID