Reduced glucose tolerance and insulin sensitivity after prolonged exercise in endurance athletes

Aim

The purpose of this study was to 1. investigate if glucose tolerance is affected after one acute bout of different types of exercise; 2. assess if potential differences between two exercise paradigms are related to changes in mitochondrial function; and 3. determine if endurance athletes differ from nonendurance-trained controls in their metabolic responses to the exercise paradigms.

Methods

Nine endurance athletes (END) and eight healthy nonendurance-trained controls (CON) were studied. Oral glucose tolerance tests (OGTT) and mitochondrial function were assessed on three occasions: in the morning, 14 h after an overnight fast without prior exercise (RE), as well as after 3 h of prolonged continuous exercise at 65% of VO₂max (PE) or 5 × 4 min at ~95% of VO₂max (HIIT) on a cycle ergometer.

Results

Glucose tolerance was markedly reduced in END after PE compared with RE. END also exhibited elevated fasting serum FFA and ketones levels, reduced insulin sensitivity and glucose oxidation, and increased fat oxidation during the OGTT. CON showed insignificant changes in glucose tolerance and the aforementioned measurements compared with RE. HIIT did not alter glucose tolerance in either group. Neither PE nor HIIT affected mitochondrial function in either group. END also exhibited increased activity of 3-hydroxyacyl-CoA dehydrogenase activity in muscle extracts vs. CON.

Conclusion

Prolonged exercise reduces glucose tolerance and increases insulin resistance in endurance athletes the following day. These findings are associated with an increased lipid load, a high capacity to oxidize lipids, and increased fat oxidation.     

视网膜血管高血压交叉压迫征的量化研究

研究视网膜血管高血压交叉压迫征的量化方法,采用局部血管图像增强的匹配滤波进行预处理、数学形态学的闭合运算进行图像平滑、线化无级扩大法确定血管边界,实施管径可逆量化自动寻优算法,为获取相关疾病诊断的数据提供一种辅助手段。     

Increased airway inflammatory cells in endurance athletes: what do they mean?

BACKGROUND: Inflammatory cells are increased in the airways of endurance athletes, but their role in causing exercise-induced respiratory symptoms and bronchoconstriction, or their possible long-term consequences, are uncertain. AIM: To put the results of athlete studies in perspective, by analysing the pathogenesis of airway cell changes and their impact on respiratory function. RESULTS: Athletes of different endurance sports at rest showed increased airway neutrophils. Elite swimmers and skiers also showed large increases in airway eosinophils and lymphocytes, possibly related to chronic, exercise-related exposure to irritants or cold and dry air, respectively. Post-exercise studies reported variable responses of airway cells to exercise, but found no evidence of inflammatory cell activation in the airways, at variance with exercise-induced neutrophil activation in peripheral blood. The increase in airway inflammatory cells in athletes can result from hyperventilation-induced increase in airway osmolarity stimulating bronchial epithelial cells to release chemotactic factors. Hyperosmolarity may also inhibit activation of inflammatory cells by causing shedding of adhesion molecules, possibly explaining why airway inflammation appears 'frustrated' in athletes. Data on exhaled nitric oxide are few and variable, not allowing conclusions about its usefulness as a marker of airway inflammation in athletes, or its role in modulating bronchial responsiveness. CONCLUSIONS: The acute and long-term effects of exercise on airway cells need further study. Airway inflammatory cells are increased but not activated in athletes, both at rest and after exercise, and airway inflammation appears to regress in athletes quitting competitions. Altogether, these findings do not clearly indicate that habitual intense exercise may be detrimental for respiratory health. Rather, airway changes may represent chronic adaptive responses to exercise hyperventilation. An improved understanding of the effects of exercise on the airways will likely have a clinical impact on sports medicine, and on the current approach to exercise-based rehabilitation in respiratory disease.     

Acute hypervolemia lengthens red cell pulmonary transit time during exercise in endurance athletes

The purpose was to determine if acute plasma volume expansion (PVE) changed red-cell pulmonary transit time (PTT) during severe exercise. Twelve endurance athletes performed 6.5 min of severe cycling exercise on different days. Pentaspan [(500 ml, infusion condition, I] or placebo [(60 ml saline), non-infusion condition, N] were infused prior to exercise. Blood gas tensions, PTT, multigated acquisition (MUGA) derived cardiac output, and oxygen uptake were measured during exercise. PTT was measured during minute 3 of exercise by radionuclide cardiography. Arterial P(O(2)) (Pa(O(2))), and alveolar-arterial oxygen pressure difference (AaD(O(2))) at minute 3 of exercise did not differ between conditions. Mean PTT at minute 3 of exercise was 0.3 sec longer in the I condition (P=0.002). However, the change in PTT between conditions was not correlated to the change in either Pa(O(2)) or AaD(O(2)). We conclude that PVE slows (lengthens) PTT without affecting pulmonary gas exchange. Therefore, rapid PTT may not be related to hypoxemia during exercise.     

Incidence of exercise induced hypoxemia in elite endurance athletes at sea level

Summary Recent evidence suggests that exercise-induced hypoxemia (EIH) may occur in healthy trained endurance athletes. However, at present, no data exist to describe the regularity of EIH in athletes or non-athletes. Therefore, the purpose of the present investigation was to determine the incidence of EIH during exercise in healthy subjects varying in physical fitness. Subjects (N=68) performed an incremental cycle ergometer test to volitional fatigue with percent arterial oxyhemoglobin saturation (%SaO₂) measured min-by-min. For the purpose of data analysis subjects were divided into three groups according to their level of physical training: 1) untrained (N=16), 2) moderately trained (N=27), and 3) elite highly trained endurance athletes (N=25). EIH was defined as a %SaO₂ of 91% during exercise. EIH did not occur in any of the untrained subjects or the moderately trained subjects. However, EIH occurred in 52% of the highly trained endurance athletes tested and was highly reproducible (r=0.95; P<0.05). These findings further confirm the existence of EIH in healthy highly trained endurance athletes and suggests a rather high incidence of EIH in this healthy population. Hence, it is important that the clinician or physiologist performing exercise testing in elite endurance athletes recognize that EIH can and does occur in the elite endurance athlete in the absence of lung disease.     

不同强度耐力运动干预下生长期大鼠骨细胞代谢水平的变化

文题释义：运动干预工程：指运用运动学、生理学、组织学、行为学和保健学等多学科方法,对人或者动物的行为、意识、细胞、组织等的研究而提出的假设,然后经过多重性质的广泛证明和实践检验成为理论的系统性工程。骨代谢：指骨的细胞持续进行的细胞代谢,既有骨的细胞之间的相互作用,也有骨髓中红细胞生成细胞、基质细胞的相互作用,它是骨改建和重建最为重要的方式。背景：随着社会的发展和人们生活水平的提升,处于生长发育敏感期的青少年健康日益受到关注。运动可改善骨细胞代谢,但有关耐力运动对生长期大鼠骨细胞代谢水平影响方面的研究不多。目的：探讨不同强度耐力运动对生长期大鼠骨细胞代谢水平的影响。方法：实验方案经成都体育学院运动与健康学院动物伦理委员会批准。选择40只大鼠适应性训练1周后,随机分为对照组、低强度耐力运动组、中强度耐力运动组、高强度耐力运动组。对照组大鼠常规饲养,不进行训练干预。各运动实验组训练12周,每周训练5 d,每天训练60 min。每2周进行一次最大摄氧量测试,根据测试结果调整后2周的训练负荷。小、中、大强度耐力运动组主负荷期的运动强度为分别为50%,65%及80%最大摄氧量。运动训练实验后观察各组大鼠骨密度、骨结构、骨代谢的指标变化。结果与结论：①关于大鼠股骨骨密度、全身骨密度,运动实验后,小、中等强度耐力运动组与对照组相比均有改善(P < 0.05);大强度耐力运动组优于小强度耐力运动组、对照组(P < 0.01)。小、中强度耐力运动组运动实验前、后相比差异有显著性意义(P < 0.05);大强度耐力运动组运动实验前、后相比差异有非常显著性意义(P < 0.01)。②关于大鼠骨小梁面积,运动实验后,小强度耐力运动组、中强度耐力运动组与对照组相比均有改善(P < 0.05);大强度耐力运动组显著优于对照组(P < 0.01);大强度耐力运动组优于小、中强度耐力运动组(P < 0.05)。③关于大鼠股骨组织中骨钙素、碱性磷酸酶、抗酒石酸酸性磷酸酶等指标,运动实验后,小、中强度耐力运动组与对照组相比均有改善(P < 0.05);大强度耐力运动组显著优于对照组   (P < 0.01);大强度耐力运动组优于小、中强度耐力运动组(P < 0.05)。④关于大鼠血清中骨钙素、碱性磷酸酶、抗酒石酸酸性磷酸酶等指标,运动实验后,小强度耐力运动组、中强度耐力运动组与对照组相比均有改善(P < 0.05);大强度耐力运动组显著优于对照组(P < 0.01);大强度耐力运动组优于小、中强度耐力运动组(P < 0.05)。⑤结果说明,不同耐力运动干预可不同程度地改善生长期大鼠骨密度、骨结构、骨组织、血清等指标,促进生长期大鼠骨生长,其中大强度耐力运动效果最佳。ORCID: 0000-0003-1455-871X(陈泽刚)中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

Effect of intermittent hypoxia on oxygen uptake during submaximal exercise in endurance athletes

The purpose of the present study was to clarify the following: (1) whether steady state oxygen uptake (O₂) during exercise decreases after short-term intermittent hypoxia during a resting state in trained athletes and (2) whether the change in O₂ during submaximal exercise is correlated to the change in endurance performance after intermittent hypoxia. Fifteen trained male endurance runners volunteered to participate in this study. Each subject was assigned to either a hypoxic group (n=8) or a control group (n=7). The hypoxic group spent 3 h per day for 14 consecutive days in normobaric hypoxia [12.3 (0.2)% inspired oxygen]. The maximal and submaximal exercise tests, a 3,000-m time trial, and resting hematology assessments at sea level were conducted before and after intermittent normobaric hypoxia. The athletes in both groups continued their normal training in normoxia throughout the experiment. O₂ during submaximal exercise in the hypoxic group decreased significantly (P<0.05) following intermittent hypoxia. In the hypoxic group, the 3,000-m running time tended to improve (P=0.06) after intermittent hypoxia, but not in the control group. Neither peak O₂ nor resting hematological parameters were changed in either group. There were significant (P<0.05) relationships between the change in the 3,000-m running time and the change in O₂ during submaximal exercise after intermittent hypoxia. The results from the present study suggest that the enhanced running economy resulting from intermittent hypoxia could, in part, contribute to improved endurance performance in trained athletes.     

Aging process of leg muscle endurance in males and females

Summary In order to estimate muscle endurance during knee extension (KME) and plantar flexion (PME) using a simple method, holding times for the half-squatting posture for KME and for the calf-raising posture for PME were measured in 3,792 males and 3,620 females aged between 6 and 79 years. The regression lines of the aging process for KME and PME in both sexes were determined. Peak values were found at 13 years in males and 12 years in females for KME, and at 15 years in males and 16 years in females for PME. The mean values increased sharply with age up to each peak and then decreased abruptly to a low level at around 20 years, thereafter declining gradually. The values of KME as a percentage of the peak value were 71, 75 and 34 at the ages of 6, 20 and 70–79 years respectively in males, while the corresponding values were 80, 77 and 36 for females. The values of PME at these ages were 34, 93 and 69 in males and 54, 91 and 73 in females. The mean values for males were generally higher than those for females. These results suggest that endurance of the leg muscles differs according to age, sex and the region of the leg muscle. These data will be useful as standard values for evaluating endurance and for prescribing suitable exercise for the promotion of physical fitness.     

Ultrasound guided fine-needle aspiration cytology: Diagnosis of hydatid disease of the abdomen and thorax

Eight cases of hydatid disease of the abdomen and thorax were diagnosed by fine-needle aspiration (FNA) cytology under ultrasound guidance. the age of the patients ranged from 28 to 60 yr with a median of 34.5 yr; the male to female ratio was 2:6. None of the cases were diagnosed clinically as hydatid diseases but following ultrasonography suspicion of hydatid cyst was raised in two cases. the locations of cysts were the liver in six cases, the lung in one case, and the mediastinum in one case. FNA yielded clear fluid in five cases and turbid fluid in three cases. Laminated cyst wall, scolices, and hooklets were observed in one case, scolices and hooklets were present in two cases, and laminated cyst wall along with hooklets were seen in two cases. the remaining three cases showed only laminated cyst walls which yielded positive reaction with periodic acid-Schiff reaction. Inflammatory cell reaction in the form of neutrophils was observed in four cases, including the three cases where turbid fluid was aspirated. Epithelioid cell reaction was present in one case. None of our eight cases showed any untoward allergic reaction following FNA. © 1995 Wiley- Liss, Inc.     

经颅直流电刺激下健康成人肌肉力量及耐力表现的Meta分析

目的:目前经颅直流电刺激在运动表现方面的研究尚处于起步阶段,且已有的研究结论存在不一致性.文章旨在定量评价经颅直流电刺激对健康成人肌肉力量与耐力表现的影响,以期为应用新型神经电生理技术提高肌肉功能提供新证据.方法:通过检索Web of Science(WOS)、PubMed、Sport Discus、CNKI数据库,检...     

Effect of endurance training on muscle microvascular filtration capacity and vascular bed morphometry in the elderly

Aim: Exercise training is a strong stimulus for vascular remodelling and could restore age‐induced vascular alterations. The purpose of the study was to test the hypothesis that an increase in vascular bed filtration capacity would corroborate microvascular adaptation with training. Methods: We quantified (1) microvascularization from vastus lateralis muscle biopsy to measure the capillary to fibre interface (LC/PF) and (2) the microvascular filtration capacity (K_f) in lower limbs through a venous congestion plethysmography procedure. Twelve healthy older subjects (74 ± 4 years) were submitted to a 14‐week training programme during which lower‐limbs were trained for endurance exercise. Results: The training programme induced a significant increase in the aerobic exercise capacity of lower limbs (+11%Vo _2peak; P < 0.05; +28% Citrate Synthase Activity; P < 0.01). K_f was largely increased (4.3 ± 0.9 10^?3 mL min^?1 mmHg^?1 100 mL^?1 post‐training vs. 2.4 ± 0.8 pre‐training, mean ± SD; P < 0.05) and microvascularization developed as shown by the rise in LC/PF (0.29 ± 0.06 post‐ vs. 0.23 ± 0.06 pre‐training; P < 0.05). Furthermore, K_f and LC/PF were correlated (r = 0.65, P < 0.05). Conclusion: These results demonstrated the microvascular adaptation to endurance training in the elderly. The increase in K_f with endurance training was probably related to a greater surface of exchange with an increased microvessel/fibre interface area. We conclude that measurement of the microvascular filtration rate reflects the change in the muscle exchange area and is influenced by exercise training.     

Reference Diameters of the Abdominal Aorta and Iliac Arteries in the Korean Population

Purpose

It is important to know the normal diameter of artery throughout the body so that clinicians are able to determine when an artery becomes aneurysmal. However, there are no previous studies on the normal diameter of arteries in the general Korean population. The purpose of this article is to determine the normal reference diameters of the abdominal aorta and iliac arteries in the Korean population.

Materials and Methods

We recruited the study population from three cities in Korea for the abdominal aortic aneurysm (AAA) screening. We measured the diameter of the aorta and iliac arteries. We analyzed the reference diameter of the population without AAA. The results were analyzed by Student''s t-test and ANOVA on SPSS version 19. A p value <0.05 was considered to be statistically significant.

Results

One thousand two hundred and twenty-nine people were enrolled. 478 men and 751 women, with a mean age of 63.9±10.1 years (range 50 to 91) were examined. Eleven out of 1229 (0.89%) were diagnosed with AAA. In the population of 1218 people without AAA, the mean diameters (cm) of male/female were 2.20/2.11 (p<0.001) at suprarenal, 2.04/1.90 (p<0.001) at renal, 1.90/1.79 (p<0.001) at infrarenal, 1.22/1.17 (p<0.001) at right iliac and 1.47/1.15 (p=0.097) at the left iliac, respectively. There was a significantly larger diameter in the male population. The diameter of each level increased with age.

Conclusion

The normal reference diameter of the infrarenal abdominal aorta in the Korean population is 1.9 cm in males and 1.79 cm in females. The diameter of the abdominal aorta increases with age.     

Effects of endurance training on hyperammonaemia during a 45-min constant exercise intensity

Summary Eleven laboratory-pretrained subjects (initial =54 ml·kg⁻¹·min⁻¹) took part in a study to evaluate the effect of a short endurance training programme [8–12 sessions, 1 h per session, with an intensity varying from 60% to 90% maximal oxygen consumption ] on the responses of blood ammonia (b[NH ₄ ⁺ ]) and lactate (b[la]) concentrations during progressive and constant exercise intensities. After training, during which did not increase, significant decreases in b[NH ₄ ⁺ ], b[la] and muscle proton concentration were observed at the end of the 80% constant exercise intensity, although b[NH ₄ ⁺ ] and b[la] during progressive exercise were unchanged. On the other hand, no correlations were found between muscle fibre composition and b[NH ₄ ⁺ ] in any of the exercise procedures. This study demonstrated that a constant exercise intensity was necessary to reveal the effect of training on muscle metabolic changes inducing the decrease in b[NH ₄ ⁺ ] and b[la]. At a relative power of exercise of 80% , there was no effect of muscle fibre composition on b[NH ₄ ⁺ ] accumulation.     

Higher blood vessel density in comparison to the lymphatic vessels in oral squamous cell carcinoma

Introduction: Oral squamous cell carcinoma (OSCC) is characterized by local invasion and the development of cervical metastasis. In the tongue, an association between the invasion of the lymphatic vessels and the development of metastasis in the regional lymph nodes has been demonstrated. Moreover, invasion of the blood vessels is associated with greater recurrence and poorer prognoses. Therefore, the presence and density of lymphatic and blood vessels in intra- and peritumoral tissues should play an important role in the progression, dissemination and metastasis of carcinomas. However, the evidence regarding OSCC is inconclusive. The aim of this study was to determine the comparison and association between the lymphatic (D2-40) and blood vessel (CD34) densities in intratumoral OSCC tissue. Materials and Methods: Thirty-seven cases diagnosed as OSCC between the years 2000 and 2008 were obtained from the Anatomic Pathology Service of the School of Dentistry, University of Chile. The immunohistochemical markers D2-40 and CD34 were used, and the densities (mm²) of lymphatic vessels (LVD) and blood vessels (BVD) in the intratumoral region were determined. The relationship between LVD and BVD values was evaluated. Results: There were significant association between the CD34 and D2-40 expression (rho=0.4, P<0.05) and between the LVD and the location in the tongue (P=0.019). The BVD was greater (128.0 vessels/mm²) than the LVD (42.9 vessels/mm²), and there was a positive correlation between the LVD and BVD. Conclusions: In OSCC, the BVD is greater than the LVD, and there is a moderate correlation between the two quantities.     

A comparison of strength and muscle endurance in strength-trained and untrained women

Summary Muscular strength and fatigability of strength-trained (ST) and untrained (UT) women were compared during a 6-min bout of maximal rhythmic exercise involving the elbow flexor muscles given at a rate of 30 contractions · min^–1. Fifteen ST and 15 UT subjects, aged 18–34 years and pair-matched for body size, were tested for differences in initial strength, final strength, absolute endurance, relative endurance, and rate of fatigue. Results revealed a significant difference in initial strength, final strength, and absolute endurance in favor of ST subjects. No significant difference was found for relative endurance, and rates of fatigue were similar for both groups. It is concluded that muscular strength and endurance are enhanced in women engaged in a training program designed primarily to increase muscular strength and hypertrophy, but fatigability is not affected.     

Histological characteristics of tumor in vessels and lymph nodes are significant predictors of progression of invasive ductal carcinoma of the breast: a prospective study

Invasive ductal carcinomas (IDCs) of the breast are composed of primary invasive tumors as well as tumor cells in blood vessels and lymph nodes. The purpose of this study was to determine whether the histological characteristics of tumor in the vessels and nodes are significantly associated with outcome. In a series of 393 patients, multivariate analyses showed that in IDCs without nodal metastasis and with fibrotic focus dimension, lymph vessel tumor emboli with >6 apoptotic figures and those invading >3 mm from the tumor margin had significantly higher hazard rates (HRs) for recurrence (P<0.05). In IDCs with 1 to 3 nodal metastases, >2 apoptotic figures in tumor emboli in blood vessels and >5 invaded lymph vessels were associated with significantly higher HRs for tumor recurrence and death (P<0.005). In IDCs with 4 or more nodal metastases, nodal tumors with >5 mitotic figures and >5 nodes with extranodal extension were associated with significantly higher HRs for tumor recurrence or death (P<0.05). We conclude that several histological characteristics of tumors in vessels and nodes have significant implications for the progression of IDCs.