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81.
Summary The effects on heart rate, oxygen uptake, and pulmonary ventilation of muscular exercises, including both dynamic contractions, either simple or combined, were studied in 4 male subjects, aged 21 to 23 years. The dynamic work consisted in cycling on an ergometric bicycle at three power levels: 40, 80, and 100 W. The static work consisted in pushing against, pulling and holding with the arms a 6, 9, 12, or 18 kg load. The physiological effects are expressed as cardiac cost (HR), oxygen cost (VO2) and ventilation cost (V). The physiological cost of the combined work increases according to the cycling power and to the isometric load developed. A statistical analysis shows that the costs of combined work are not different from the sum of the costs of the static and dynamic contractions measured separately. Thus, the physiological responses to the combinations investigated are of an additive type. 相似文献
82.
目的:观察大鼠7周大负荷游泳训练及人参二醇组皂甙(PDS)对大鼠股四头肌α-肌动蛋白mRNA表达的影响。方法:采用Northernblot分析7周大负荷游泳训练后恢复期大鼠股四头肌α-肌动蛋白mRNA表达水平及PDS对其影响。结果:α-肌动蛋白mRNA杂交信号的扫描积分光密度值(A),运动·盐水组较安静组略强;运动·PDS,扫描积分光密度值(A)显著强于运动·盐水组和安静组,运动·甲睾组与运动·盐水组表达无明显差异。结论:PDS可提高长期耐力运动大鼠股四头肌α-肌动蛋白mRNA表达,从而提高耐力运动能力;长期应用外源性雄激素对耐力训练大鼠股四头肌α-肌动蛋白无明显提高,这可能与外源睾酮对内源性睾酮分泌的抑制有关。 相似文献
83.
Stringer WW Whipp BJ Wasserman K Pórszász J Christenson P French WJ 《European journal of applied physiology》2005,93(5-6):634-639
Published literature asserts that cardiac output (=O2×1/C(a-v)O2) increases as a linear function of oxygen uptake with a slope of approximately 5–6 during constant work rate exercise. However, we have previously demonstrated that C(a-v)O2 has a linear relationship as a function of O2 during progressively increasing work rate incremental exercise. Therefore, we hypothesized that may indeed have a non-linear relationship with respect to O2 during incremental, non-steady state exercise. To investigate this hypothesis, we performed five maximal progressive work rate exercise studies in healthy human subjects. was determined every minute during exercise using measured breath-by-breath O2, and arterial and pulmonary artery measurements of PO2, hemoglobin saturation, and content. was plotted as a function of O2 and the linear and non-linear (first order exponential and hyperbolic) fits determined for each subject. Tests for linearity were performed by assessing the significance of the quadratic terms added to the linear relation using least squares estimation in linear regression. Linearity was inadequate in all cases (group P<0.0001). We conclude that cardiac output is a non-linear function of O2 during ramp-incremental exercise; the pattern of non-linearity suggests that while the kinetics of are faster than those of O2 they progressively slow as work rate (and O2) increases. 相似文献
84.
Palmieri EA Palmieri V Innelli P Arezzi E Ferrara LA Celentano A Fazio S 《European journal of applied physiology》2005,94(1-2):113-117
In older healthy men, aerobic exercise capacity is related to postischemic flow-mediated dilation of the brachial artery (FMD), but corresponding data in a younger population is not available. In addition, whether submaximal aerobic exercise performance also correlates with this kind of vasomotor reactivity is not known. Therefore, in 15 nonsmoking young healthy men [age 27 (5) years; body mass index: 24 (2) kg/m2; mean (SD)] with different levels of ordinary physical activity, but not performing upper-extremity training, we measured FMD at 1 min after reactive hyperemia, and pulmonary oxygen uptake (O2) at ventilatory anaerobic threshold (O2AT) and at peak effort (peak O2) during an incremental exercise on a treadmill. In our participants, FMD was 9.1 (3.4)%, O2AT was 40.72 (5.92) ml/kg per min, and peak O2 was 52.95 (8.13) ml/kg per min. Using bivariate Pearsons correlation, and in separate multivariate regression analyses, O2AT and peak VO2 showed a significant and reasonably good correlation with FMD (r=0.84, P<0.001 and r=0.77, P=0.001, respectively), independent of age, body mass index and serum total cholesterol (=0.77, P<0.001, R2 of the overall model=0.79 and =0.70, P<0.005, R2 of the overall model=0.69, respectively). Our data provide evidence suggesting that in young healthy men a higher submaximal and maximal aerobic exercise performance is associated with a greater FMD of peripheral conduit arteries. 相似文献
85.
Kamran Sardari 《Comparative clinical pathology》2007,16(2):97-102
Local injection of a mixture of beta-aminopropionitril fumarate (BAPN-f) and sodium hyaluronate (NaH+) together with controlled exercise were evaluated for treatment of superficial digital flexor tendon (SDFT) injuries in horses.
Fourteen mixed breed horses with subacute SDF tendon injuries in forelimbs were randomly assigned to two groups. One group
received BAPN-f (0.7 mg/ml) and the other received NaH+ (10 mg/ml) all by intratendinous injection. Controlled exercise started during the first week after intratendinous treatment
and continued for 12 weeks. Cross-sectional area (CSA) of the SDFT, diameter of the SDFT, and relative area of the lesion
(presence of CSA) were measured by ultrasonographic examination. Lesions were semiquantitatively graded for echogenicity on
a scale of 0 to 4. The lesion severity in CSA was significantly reduced by BAPN and NaH compared to those horses treated by
BAPN only (p < 0.05). Lesion echogenicity score was significantly higher in horses treated with BAPN and NaH+ at day 0 compared to horses treated with BAPN (p < 0.05). At the end of the study, lesion echogenicity score was significantly reduced in the horses treated with BAPN and
NaH+ compared to horses treated by BAPN only (p < 0.05). According to the results of the present study, a combination of BAPN-f and NaH+ has a greater beneficial effect on tendon healing and remodeling in horses, as assessed by sonographic examination, compared
to treatment with single drugs. 相似文献
86.
Yoshiharu Yamamoto Mitsumasa Miyashita Richard L. Hughson Shin-ichi Tamura Minoru Shinohara Yoshiteru Mutoh 《European journal of applied physiology》1991,63(1):55-59
Summary The purpose of this study was to examine whether the ventilatory threshold (Th
v) would give the maximal lactate steady state ([1a]ss, max), which was defined as the highest work rate (W) attained by a subject without a progressive increase in blood lactate concentration [1a]b at constant intensity exercise. Firstly, 8 healthy men repeated ramp-work tests (20 W·min–1) on an electrically braked cycle ergometer on different days. During the tests, alveolar gas exchange was measured breath-by-breath, and theW atTh
v (W
Th
v) was determined. The results of two-way ANOVA showed that the coefficient of variation of a singleW
Th
v determination was 2.6%. Secondly, 13 men performed 30-min exercise atW
Th
v (Th
v trial) and at 4.9% aboveW
Th
v (Th
v + trial), which corresponded to the 95% confidence interval of the single determination. The [1a]b was measured at 15 and 30 min from the onset of exercise. The [1a]b at 15 min (3.15 mmol·1–1, SEM 0.14) and at 30 min (2.95 mmol·1–1, SEM 0.18) were not significantly different inTh
v trial. However, the [1a]b ofTh
v+ trial significantly increased (P<0.05) from 15 min (3.62 mmol·1–1, SEM 0.36) to 30 min (3.91 mmol·1–1, SEM 0.40). These results indicate thatTh
v gives the [1a]ss,max, at which one can perform sustained exercise without continuous [1a]b accumulation. 相似文献
87.
Y. Epstein J. Rosenblum R. Burstein M. N. Sawka 《European journal of applied physiology》1988,57(2):243-247
Summary The present study was undertaken to examine the energy cost of prolonged walking while carrying a backpack load. Six trained subjects were tested while walking for 120 min on a treadmill at a speed of 1.25 m · s–1 and 5% elevation with a well fitted backpack load of 25 and 40 kg alternately. Carrying 40 kg elicited a significantly higher (p<0.01) enery cost than 25 kg. Furthermore, whereas carrying 25 kg resulted in a constant energy cost, 40 kg yielded a highly significant (p<0.05) increase in energy cost over time. The study implies that increase in load causes physical fatigue, once work intensity is higher than 50% maximal work capacity. This is probably due to altered locomotion biomechanics which in turn lead to the increase in energy cost. Finally, the prediction model which estimates energy cost while carrying loads should be used with some caution when applied to heavy loads and long duration of exercise, since it might underestimate the acutal enery cost. 相似文献
88.
N. B. Ruderman H. Park V. K. Kaushik D. Dean S. Constant M. Prentki A. K. Saha 《Acta physiologica (Oxford, England)》2003,178(4):435-442
An increasing body of evidence has revealed that activation of adenosine monophosphate (AMP)‐activated protein kinase (AMPK)‐activated protein kinase increases fatty acid oxidation by lowering the concentration of malonyl coenzyme A (CoA), an inhibitor of carnitine palmitoyl transferase 1. Studies carried out primarily in skeletal muscle suggest that AMPK modulates the concentration of malonyl CoA by concurrently phosphorylating and inhibiting acetyl CoA carboxylase (ACC), the rate limiting enzyme in malonyl CoA synthesis, and phosphorylating and activating malonyl CoA decarboxylase (MCD), an enzyme involved in its degradation. We have recently observed that AMPK and MCD activities are increased and ACC activity diminished in skeletal muscle, liver and, surprisingly, in adipose tissue 30 min following exercise (treadmill run) in normal rats. In liver and adipose tissue these changes were associated with a decrease in the activity of glycerol‐3‐phosphate acyltransferase (GPAT), which catalyses the first committed reaction in glycerolipid synthesis and, which like ACC, is phosphorylated and inhibited by AMPK. Similar changes in ACC, MCD and GPAT were observed following the administration of 5‐aminoimidazole 4‐carboxamide‐riboside (AICAR), further indicating that the exercise‐induced alterations in these enzymes were AMPK‐mediated. Conclusions: (1) AMPK plays a major role in regulating lipid metabolism in multiple tissues following exercise. (2) The net effect of its activation is to increase fatty acid oxidation and diminish glycerolipid synthesis. (3) The relevance of these findings to the regulation of muscle glycogen repletion in the post‐exercise state and to the demonstrated ability of AMPK activation to decrease adiposity and increase insulin sensitivity in rodents remains to be determined. 相似文献
89.
Summary Differing results have been reported concerning the direction and quantity of the electromyogram (EMG) amplitude response to changes in tissue temperature. The EMG signals from the soleus muscle of six healthy human subjects were therefore recorded during dynamic exercise (concentric contractions) at ambient temperatures of 30°C and 14°C. The mean skin temperature
above the muscle investigated was 32.9° C and 21.7° C, respectively. The core temperature, estimated by rectal temperature, was unchanged. The cooling of the superficial tissues caused approximately a doubling of the EMG amplitude. For the probability level 0.9 in the amplitude probability distribution function, the average signal level increased from 73 V to 135 V (P=0.02). The average mean power frequency of the EMG signal was reduced from 142 Hz to 83 Hz (P=0.004). The amplitude increase was not due to shivering but other possible explanations are presented. As the changes in T
sk investigated were within the range which may occur normally during the working hours, it was concluded that T
sk should be carefully controlled in vocational EMG studies. 相似文献
90.
P. Magnus A. -L. BØrresen P. K. Opstad J. F. Bugge K. Berg 《European journal of applied physiology》1984,53(1):21-24
Summary Effects of four days of intense physical activity on serum concentrations of total triglycerides, total cholesterol and apolipoproteins A-I, A-II, and B were studied in 35 well-trained young men. Serum total triglyceride levels decreased to 70% of baseline levels after 24 h, and fell further to 50% of baseline levels after 4 days. Serum levels of total cholesterol fell steadily to about 80% of baseline levels on the 4th day. Apo-B levels fell to 85% of baseline levels after 24 h, and remained at that level. Apo A-I fell to about 90%, and apo A-II to about 80% of baseline levels, causing a significant increase in the ratio of apo A-I to apo A-II. The intraindividual changes in apo B were positively correlated to changes in cholesterol during the first day (r=0.60). The changes in apo A-I and apo A-II had no significant correlation with changes in total cholesterol or triglycerides, or with one another, suggesting that apo A-I and apo A-II are metabolized independently during conditions of hard physical exercise. 相似文献