Validity and reliability of a low-cost dynamometer to assess maximal isometric strength of upper limb     

Natalia Romero-Franco  Juan C Fernández-Domínguez  Juan A Montaño-Munuera  Javier Romero-Franco  Pedro Jiménez-Reyes 《Journal of sports sciences》2019,37(15):1787-1793

Muscle imbalance and deficit are key parameters for guiding rehabilitation and sports sessions and avoiding injuries. However, the high cost and non-portable nature of most instruments employed for muscle strength assessment frequently hamper an affordable evaluation in field conditions. This study evaluated the validity and reliability of a low-cost digital dynamometer to assess the maximal isometric strength of upper limb muscles. Fourteen physically active volunteers performed the main movements of the upper limb at maximal isometric strength: flexion-extension, internal-external rotation and abduction-adduction of the shoulder; and flexion-extension of both elbow and wrist. Validity was examined by comparing the strength values from the low-cost digital dynamometer and those measured by an isokinetic dynamometer, assumed as the gold standard. The correlation between both devices was perfect (r > 0.913), while Bland-Altman plots showed absolute agreement between both devices, the maximum range of the values of bias was ?0.99–1.00 N in wrist extension. Inter-tester and intra-tester reliability were excellent for all movements (ICC ≥ 0.855). The low-cost digital dynamometer showed strong validity and excellent reliability in assessing maximal isometric strength during the main movements of the upper limb. Professionals may use it for an affordable isometric muscle strength assessment in field situations.  相似文献   

Effects of periodic carbohydrate ingestion on endurance and cognitive performances during a 40-km cycling time-trial under normobaric hypoxia in well-trained triathletes     

Yi-Hung Liao  Toby Mündel  Yan-Ting Yang  Chen-Chan Wei  Shiow-Chwen Tsai 《Journal of sports sciences》2019,37(16):1805-1815

The purpose of this study was to examine CHO ingestion on a cognitive task using a field-simulated time-trial (TT) under hypoxia in well-trained triathletes. Ten male triathletes (age: 22.1 ± 1.1 years; VO₂max: 59.4 ± 1.4 ml/kg/min) participated in this double-blind/crossover/counter-balanced design study. Participants completed 3 TT trials: 1) normoxic placebo (NPLA; FiO₂ = 20.9%), 2) hypoxic placebo (HPLA; FiO₂ = 16.3%), and 3) hypoxic CHO (HCHO; 6% CHO provided as 2 ml/kg/15 min; FiO₂ = 16.3%). During the TT, physiological responses (SpO₂, HR, RPE, and blood glucose/lactate), cognitive performance, and cerebral haemodynamics were measured. Hypoxia reduced TT performance by ~3.5–4% (p < 0.05), but CHO did not affect TT performance under hypoxia. For the cognitive task, CHO slightly preserved exercise-induced cognitive reaction speed but did not affect response accuracy during hypoxic exercise. However, CHO did not preserve the decreased Hb-Diff (cerebral blood flow, CBF) and increased HHb in the prefrontal lobe (p < 0.05) during hypoxic exercise, and CHO failed to preserve hypoxia-suppressed prefrontal CBF and tissue oxygen saturation. In conclusion, the present study demonstrates that CHO is effective in sustaining reaction speed for a cognitive task but not promoting TT performance during hypoxic exercise, which would be important for strategy-/decision-making when athletes compete at moderate high-altitude.  相似文献   

Physiological responses in different intensities of resistance exercise – Critical load and the effects of aging process     

Vivian Maria Arakelian  Cássia da Luz Goulart  Renata Gonçalves Mendes  Nuno Manoel de Sousa  Renata Trimer  Solange Guizilini 《Journal of sports sciences》2019,37(12):1420-1428

Aim was to identify critical load (CL) in young and elderly apparently healthy male cohorts. To contrast the metabolic, cardiovascular and perceptual responses on CL according to age. We evaluated 12 young (23 ± 3 years) and 10 elderly (70 ± 2 years) apparently healthy active males, who underwent: (1) 1 repetition maximum (1RM) test on a 45° Leg Press; (2) on different days, three high-intensity resistance exercise constant load tests (60%, 75% and 90% 1RM) until fatigue (Tlim). Absolute values of both the CL asymptote and curvature constant (kg) were significantly lower in elderly subjects (P < 0.05). In contrast, elderly subjects demonstrated a significantly higher number of repetitions at CL when compared with young subjects (P < 0.05). As expected, oxygen uptake (VO₂) and heart rate (HR) during maximal aerobic exercise testing were significantly reduced in older subjects. However, percent-predicted aerobic capacity were higher in older subjects (P < 0.05). In addition, blood lactate ([La^?]) corrected to Tlim and rating of perceived exertion values were greater in younger subjects at all intensities (P < 0.05). These findings, despite reduced force production in older subjects, endurance-related parameters are well preserved according to age-adjusted percent-predicted values in apparently healthy males.  相似文献   

NiCo_2O_4纳米结构阵列的水热合成与氧析出特性研究     

陈传胜  张作胜  陈伟杰  乔浏 《安徽职业技术学院学报》2020,(1):16-19,41

钴酸镍纳米材料具有良好的电催化氧析出反应(Oxygen Evolution Reaction,OER)活性,是一种很有发展潜力的非贵金属电催化材料。文章以碳纤维纸为基底,采用水热合成的方法对纳米结构钴酸镍的生长进行了系统的研究,分别考察了生长温度、前驱体浓度和配比、生长时间对产物的形貌、尺寸、物相结构、OER电化学性能的影响,通过对比分析后发现在生长温度100℃、生长时间5h、镍钴比为2:1时所获得的多孔片状钴酸镍纳米结构具有最佳的OER特性。  相似文献   

Protective Role of <Emphasis Type="SmallCaps">l</Emphasis>-Arginine Against Free-Radical Mediated Oxidative Damage in Patients with Unstable Angina     

Tripathi P  Chandra M  Misra MK 《Indian journal of clinical biochemistry : IJCB》2010,25(3):302-306

Unstable angina is a critical condition of heart resulting from narrowing of vessels supplying blood to heart. Ischemia of the myocardium leads to oxidative stress and severe tissue damage. The objective of the present study was to determine the effect of l-arginine administration on the oxidant–antioxidant homeostasis which otherwise gets imbalanced in patients with cardiovascular diseases. The results obtained, show improvement in the oxidant–antioxidant levels of the subjects upon incorporation of l-arginine. Our findings suggest that supplementation of l-arginine along with regular anti-anginal therapy may be beneficial to the patients of unstable angina.  相似文献   

关于最大平面图着色的探讨——希伍德的反例是4-色的   总被引：5，自引：0，他引：5  

董德周 《科技通报》2002,18(4):304-309

通过最大平面图和四色猜想的介绍及对最大平面图着色的分析，揭示了最大平面图着色是四色定理普遍证明的核心。应用证明五色定理的方法（肯普链），证明了希伍德的反例是4－色的，阐明了“希伍德的反例从5－色的到4－色的”具有深远的历史意义。  相似文献   

烟雾吸入伤早期氧化与抗氧化动态平衡变化的实验研究   总被引：1，自引：0，他引：1  

谢尔凡  杨宗城 《科技通报》1997,13(1):39-43

采用大鼠烟雾吸入伤模型，动态观察了伤后血浆、支气管肺泡灌洗液（ＢＡＬＦ）和肺组织中超氧化物歧化酶（ＳＯＤ）活性、丙二醛（ＭＤＡ）和共轭二烯（ＣＤ）含量的变化，辅以动脉血气分析、肺水量测定、ＢＡＬＦ中白细胞分类计数和病理检查．结果发现，伤后动物出现急性呼吸衰竭和严重肺水肿，肺内大量炎细胞聚集浸润；血浆、ＢＡＬＦ及肺组织中ＳＯＤ活性明显降低，ＣＤ和ＭＤＡ含量显著增加，ＭＤＡ／ＳＯＤ比值亦明显增高，且与ＢＡＬＦ中中性粒细胞数增加显著相关，提示氧化与抗氧化平衡失调可能在急性烟雾吸入性肺损伤的发生发展中起重要作用  相似文献   

Dietary restriction (DR) and its advantages     

M. N. Astagimath  Shrinivas B. Rao 《Indian journal of clinical biochemistry : IJCB》2004,19(1):1-5

Dietary restriction (DR) also called dietary control or calorie restriction is reported to have many advantages with regard to human health. It leads to suppression of obesity, mitigates free radicals and increases available antioxidants which are accounted for extending the life span of individuals. DR is also reported to induce synthesis of heat shock proteins in animals as a control mechanism against stress. Further, it is known to play a significant role in decreasing toxicity and lethality due to a variety of toxic chemicals and drugs by stimulating tissue repair damaged by the toxicants leading to restoration of intact organ and its functions. Moreover, extensive work done on animals indicate DR has an important role in suppressing certain types of cancer. In this review an effort is made to highlight the various advantages of DR from the point of human health perspective.  相似文献   

求解最大流问题的"构造式"算法     

郏宣耀  张帆 《深圳职业技术学院学报》2005,4(1):18-20,30

在前向推进最大流算法的基础上作了改进，提出一种求解最大流问题的“构造式”算法。该算法应用图的深度优先搜索原理，摒弃前向推进最大流算法的并行控制而着眼于每一支流的依次增广，逐步构造中间过程“构造图”的结构并最终得到网络最大流。该方法增强了算法的直观性和可控性，易于实现。  相似文献   

Maximal Criterion Validity and Scale Criterion Validity: A Latent Variable Modeling Approach for Examining Their Difference     

Tenko Raykov  Siegfried Gabler  Dimiter M. Dimitrov 《Structural equation modeling》2016,23(4):544-554

This article studies the difference between the criterion validity coefficient of the widely used overall scale score for a unidimensional multicomponent measuring instrument and the maximal criterion validity coefficient that is achievable with a linear combination of its components. A necessary and sufficient condition of their identity is presented in the case of measurement errors being uncorrelated among themselves and with a used criterion. An upper bound of the difference in these validity coefficients is provided, indicating that it cannot exceed the discrepancy between the maximal reliability and composite reliability indexes. A readily applicable latent variable modeling procedure is discussed that can be used for point and interval estimation of the difference between the maximal and scale criterion validity coefficients. The outlined method is illustrated with a numerical example.  相似文献