THE VOLLEYBALL APPROACH: AN EXPLORATION OF RUN-UP LAST STRIDE LENGTH WITH JUMP HEIGHT AND DEVIATION IN LANDING

The main aim of present research was to find out a significant correlation between approach run-up last stride length and the height of jump and landing deviation. Fourteen top elite volleyball players have been served for this study. A Mikro-Mak Motion Analyzer with Win-Analyze program has been used for this study. A Philips video camera with 240 frames per second has also been used to better trace the markers on the shoulder, hip, knee, ankle, and toe. The program enabled us to find out the displacement and velocity of all parts and especially the toes’ in order to measure the different last stride lengths and the deviation from vertical axis. Although we were expecting to get a significant correlation between this parameter and jump height, as in long stride the CG is displaced in longer range with higher horizontal motion than when the player jumps with shorter stride, but the findings did not support this idea. The results are given in Tables 1-4

THE RELATIONSHIP BETWEEN THE LACTATE TURNPOINT AND THE TIME AT VO2 max DURING A CONSTANT VELOCITY RUN TO EXHAUSTION

The aim of present work was to examine the relationship between the running velocity at the lactate turn-point (vLTP) and the time at which VO can be sustained (TVO ) during a continuous run to exhaustion at a minimal running velocity that yields VO (vVO ). Pearson’s correlation coefficient was used to determine the association between vLTP and TVO and between other selected physiological variables. Correlations between the relative vLTP and v VO was significant (r=0.63) at the

Voltage control in distributed generation systems based on complex network approach

In this paper, a new approach for modeling of voltage control problem in distributed generation systems based on the complex network theory is proposed. Distributed generationsystems (DGS) including renewable energy sources are highly complex nonlinear dynamical systems by nature. There are many theoretical and practical challenges to apply the existing control technologies to them. The novel approach, introduced in this paper, embeds the complex network theory into the voltage control problem of DGS; i.e. the voltage control of DGS is introduced as a synchronization problem in complex networks. Complex network methodology shows a promising simplification inthe analysis as well as timely response in large-scale systems. Thanks to the well-developed graph theory as well as advancements in control of multi-agent systems,the model presented in this paper, candealwith real-time hierarchical multi-objective requirements of control problems in DGS. Finally, the pinning control approach is applied to the model in order to solve the voltage synchronization problem of the microgrid

The Effects of Excessive Aerobic Continuous and Interval Training Programs on Plasma Lipoproteins and Serum CRP in Women

Abstract: Background & Aims: Blood inflammatory factors have been recognized as major risk factors of cardiovascular diseases. The purpose of this study was to compare the efficacy of two methods of excessive aerobic continuous and interval training on plasma lipoproteins (TC, TG, LDL, HDL, VLDL) and serum CRP in women. Methods: A total of 20 women aged 35-45 years were randomly divided into the two groups of aerobic continuous and interval training. Subjects participated in an 8- week either aerobic continuous or interval running program (3 day / week, at 65-75% HRmax). Twenty four hours before the first training program and 24 hours after the final training session blood samples were collected in a fasted state. Results: No significant difference was found between the two groups in regard to TC, TG, LDL, HDL, VLDL and CRP levels in both pre- and post- tests. Aerobic continuous training induced significant decrease in TC, LDL, CRP and increase in HDL. Aerobic interval training induced significant decrease in TC, TG, LDL, CRP and increase in HDL too, but no significant difference was found between the two methods of training on plasma lipoproteins and serum CRP. Conclusion: Excessive aerobic continuous and interval training can have similar effects on plasma lipoproteins and serum CRP in women. Keywords: Aerobic exercise, Lipoproteins, C-Reactive protein, Cardiovascular diseases, Wome

Enhancing stability of cooperative secondary frequency control by link rewiring

In this paper, we propose an optimization methodology to find the optimal topology for the data communication network in distributed frequency control of power system. In order to implement a distributed cooperative control scheme, local controllers often share their data over a data communication network. Structure of this network has a major role in determining stability of secondary cooperative frequency control of a microgrid; and thus the structure can be optimized to have the best performance. Although distributed control signals may be delayed or dropped during their transmission, confident margin of the stability can reduce side effects of these inherent problems and makes power system more reliable. In this situation, the challenge is to find the best topology of data communication network giving the highest margin of the system stability. In this paper we define the problem of finding the best topology as an optimization problem. An eigenvalue perturbation analysis approach is used to approximate sensitivity of the stability performance of secondary cooperative control to adding/removing data communication links. Then, the optimization problem is solved using a simulated annealing optimization strategy. Our numerical simulations on sample networks show that the proposed rewiring-based optimization can successfully find the network structure with (near)-optimal stabilizability performance

A new metric for measuring infleunce of nodes in cooperative frequency control of distributed generation systems

Lack of inertia in distributed power generation systems (which include renewable energy resources) makes the frequency control problem more time critical. In such situations, the power management system should react to any unbalance of power generation and consumption considerably faster than traditional interconnected power networks. To do this, one of the generation units should be set as the master of frequency in the microgrid, while others should follow the master. The challenge is to find the best master node. In this paper, we propose a metric to rank all generation sources according to their impact on the stability of frequency in the microgrid. The metric is achieved using perturbation analysis of the dominant eigenvalue of the state matrix of the microgrid. It is easily computed and computationally cost effective for microgrids with large number of small resources. Simulation results support the accuracy of this measure in finding a good master node in microgrid. The proposed metric outperforms heuristics such as taking the master node based on degree, closeness or betweenness centrality measures

Which generation unit should be selected as control leader in secondary frequency control of microgrids?

In this paper, we propose a novel metric to choose control leaders in secondary frequency control of microgrids. The microgrid, as the building block of distributed generation systems, is assumed to be composed of both synchronous and inverter-connected generation units, e.g., renewable sources. Here, we formulate the stability analysis of secondary cooperative control in microgrids. To control the frequency of the microgrid, the secondary control should set one (or more) of generation units as master and the others as follower. A novel metric is proposed to measure the impact of different generation sources on the rate of frequency recovery of the distributed generation power system. The proposed metric is based on the eigenvalue perturbation analysis of the state matrix of the microgrid, which includes information on the topology of both physical power and data communication networks. Using this metric, one can rank all generation units and choose the one with the largest influence as the master node. The metric is simple to compute and can be easily used in microgrids with large number of small size generation units. Numerical simulations show the effectiveness of the proposed metric over heuristic methods such as choosing the master nodes based on their degrees, betweenness centrality, or closeness centrality values in the data communication network

Relationship between Taq1A Dopamine D2 Receptor Polymorphism and Motivation to Exercise and levels of Voluntary Physical Activity

The purpose of this study was to examine the genetic basis underlying voluntary physical activity. This study explores to an association, if exists, between motivation to exercise, levels of voluntary physical activity and Taq1A gene polymorphisms. Method: 122 participants (age=24.4±5.7 yrs., 55 males & 67 females) completed the Behavioral Regulation in Exercise Questionnaire – 2 (BREQ-2) to assess their motivation to exercise and the International Physical Activity Questionnaire (IPAQ) to assess their level of physical activity. DNA was isolated from a cheek cell sample. The Taq1A genotype was identified using PCR with gene specific primers. Results: Our study included 85 normal-weight, 30 overweight, and 7 obese subjects. Three variants of DRD2 taq1A -CC (n=77, 63.1%), CT (n=35, 7.28%), and TT (n=10, 2.8%) - were identified. Internal motivation to exercise was significantly higher in the CC genotype compared to the other two genotypes (P=0.017). Conclusion: In general, intrinsic regulation factors of motivation, as well as the type of genotype, may play a major role in determining the level of physical activity. Taq1A polymorphism of the DRD2 gene is related to physical activity and body weight in young men and wome

Changes in ACTN3 gene expression and fiber type composition in flexor hallucis longus muscle after eight weeks progressive resistance training in Sprague-Dawley rats

Background: Alpha-actinins are located in the skeletal muscle Z-line and form actin–actin cross-links. It belongs to a highly conserved family of actin-binding proteins- the spectrin superfamily, which also contains the spectrins and dystrophin. Mammalian skeletal muscle has two isoforms: alpha-actinins-2 and alpha-actinins-3. However, the response of alpha-actinins to exercise training is little understood. This study examined the effects of 8 weeks of resistance training on muscle mass, ACTN3 (alpha-actinins-3) gene expression levels and fiber type composition in the flexor hallucis longus (FHL) muscle.Methods: Forty five female Sprague-Dawley rats (Initial body mass: 169.25±9gr age: 3 month) were obtained and assigned to a control (C; n=18) or exercise training (T; n=22) and pilot (P; n=5) groups. The resistance training consisted of climbing a ladder carry-ing a load suspended from the tail and the weight increased progressively. Real-time PCR and Immunohistochemistry techniques were used to measure gene expression leve-ls and myosin heavy chain (MyHC) composition, respectively.Results: Following 8 weeks of training, we observed significant increase in absolute muscle mass in FHL (P=0.01). Results showed that no significant difference was found in ACTN3 gene expression levels between training and control groups (P=0.852 respecti-vely). Also, Pearson coefficient didn't indicated any significant relationships in gene expression and Fiber type IIX in response to resistance training in FHL (r=0.12).Conclusion: However, resistance training effects on sarcomeric proteins development, these results showed no effect of resistance training on alpha-actinins-3 levels. Althou-gh alpha-actinins-3 has an important function to produce and progress of force in sarco-mere, but didn't changed significantly in response to resistance training

Adiponectin, disease, and exercise: A narrative review

Introduction:Adiponectin, the most abundant circulating peptide secreted by adipocytes, regulates metabolism through blood glucose control and fatty acid oxidation. In contrast to the initial dogma that adipose tissue is the only source of adiponectin secretion, it has recently been demonstrated that skeletal muscle can also produce and secrete it. Hence, the identification of skeletal muscle as a source of adiponectin expression has attracted the interest of many researchers to explore its role as a circulating adipokine, as well as a myokine, with autocrine/paracrine properties. Numerous animal studies have described adiponectin as a salutary cytokine because of insulin-sensitizing, anti-inflammatory, anti-atherogenic, and anti-cancer properties. Paradoxically, other evidence suggests that elevated adiponectin levels can be associated with the induction or existence of some pathologies. However, underlying mechanisms involved in this paradox are not well-understood. On the other hand, many studies have shown the beneficial effects of long-term exercise on increased adiponectin levels, regardless of exercise protocol and status of participants. However, even approximately 25 years after the discovery of adiponectin, its properties and related mechanisms responsible for its high circulating levels, as well as how it affects various tissues and organs, remain unclear. Therefore, this study aimed to summarize and discuss the literature available to date regarding the introduction of adiponectin, its receptors, and signaling pathways in adipose tissue and skeletal muscle, along with its changes in disease and exercise conditions. © 2020, Research Institute for Endocrine Sciences. All rights reserved