bluuebunny/crossref_metadata_2025 huggingface dataset:
In vitro degradation of chitosan composite foams for biomedical applications and effect of bioactive glass as a crosslinker
Authors: Martins Talita , Moreira Cheisy D. F. , Costa-Júnior Ezequiel S. , Pereira Marivalda M.
Published: February 2018

In tissue engineering applications, 3D scaffolds with adequate structure and composition are required to provide durability that is compatiblewith the regeneration of native tissue. In the present study, the degradation of novel flexible 3D composite foams of chitosan (CH) combined with bioactive glass (BG)was evaluated, focusing on the role of BG as a physical crosslinker in the composites, and its effect on the degradation process. Highly porous CH/BG composite foams were obtained, and an elevated degradation temperature and lower degradation rate compared with pure chitosan were observed, probably as a result of greater intermolecular interaction between CH and BG. The Fourier transform infrared spectroscopy (FTIR) data suggest that hydrogen bonds were responsible for the physical crosslinking between CH and BG. The results confirm that CH/BG foams can combine controllable bioactivity and degradation behavior and, therefore, could be useful for tissue regeneration matrices.
Laboratory hemostasis: from biology to the bench
Authors: Lippi Giuseppe , Favaloro Emmanuel J.
Published: February 2018

Physiological hemostasis is an intricate biological system, where procoagulant and anticoagulant forces interplay and preserves blood fluidity when blood vessels are intact, or trigger clot formation to prevent excessive bleeding when blood vessels are injured. The modern model of hemostasis is divided into two principal phases. The first, defined as primary hemostasis, involves the platelet-vessel interplay, whilst the second, defined as secondary hemostasis, mainly involves coagulation factors, damaged cells and platelet surfaces, where the so-called coagulation cascade rapidly develops. The activation and amplification of the coagulation cascade is finely modulated by the activity of several physiological inhibitors. Once bleeding has been efficiently stopped by blood clot formation, dissolution of the thrombus is essential to restore vessel permeability. This process, known as fibrinolysis, also develops through coordinate action of a vast array of proteins and enzymes. An accurate diagnosis of hemostasis disturbance entails a multifaceted approach, encompassing family and personal history of hemostatic disorders, accurate collection of clinical signs and symptoms, integrated with laboratory hemostasis testing. Regarding laboratory testing, a reasonable approach entails classifying hemostasis testing according to cost, complexity and available clinical information. Laboratory workout may hence initiate with some rapid and inexpensive “screening” tests, characterized by high negative predictive value, then followed by second- or third-line analyses, specifically aimed to clarify the nature and severity of bleeding or thrombotic phenotype. This article aims to provide a general overview of the hemostatic process, and to provide some general suggestions to optimally facilitate laboratory hemostasis testing.
Consequences of Gossiping on Women Empowerment
Authors: Umer Shumaila , Othman Zaheruddin , Hassan Kalthum Bt Haji , Umer Rahila , Rehman Habib Ur
Published: February 2018

Gossip is prevalent and is widespread in human society. Gossip has been denigrated as ‘idle talk’, mostly among women based on ‘trifling or groundless rumour’. The nature and intensity of gossiping victimise women in society. Consequently, women bear serious threat to their well standardized lives. The study aims to understand the women’s experiences with gossiping as a barrier to empowerment. This is a qualitative study with inductive approach. Men and Women are selected as a informants for this study. The data were congregated through in-depth interviews. The results indicate that gossiping or fear of being gossiped is a strong social control in the social setup of Balochistan. This prevents women from being empowered. This paper is intended to be a contribution to exploiting the ideas of women about gossiping as an essential social control or barrier for empowering women.
Heat kernel estimates for time fractional equations
Authors: Chen Zhen-Qing , Kim Panki , Kumagai Takashi , Wang Jian
Published: February 2018

In this paper, we establish existence and uniqueness of weak solutions to
general time fractional equations and give their probabilistic
representations. We then derive sharp two-sided estimates for fundamental solutions of
a family of time fractional equations in metric measure spaces.
The World Health Organization (WHO) versus The International Association of Diabetes and Pregnancy Study Group (IADPSG) diagnostic criteria of gestational diabetes mellitus (GDM) and their associated maternal and neonatal outcomes
Authors: Basri Nurul Iftida , Mahdy Zaleha Abdullah , Ahmad Shuhaila , Abdul Karim Abdul Kadir , Shan Lim Pei , Abdul Manaf Mohd Rizal , Ismail Nor Azlin Mohd
Published: February 2018

Background

Gestational diabetes mellitus (GDM) is a common medical complication in pregnancy. The aim of this study was to compare the prevalence of GDM using the World Health Organization (WHO) criteria and the International Association of Diabetes and Pregnancy Study Group (IADPSG) criteria in our population. We further compared the incidence of adverse maternal and neonatal outcomes in women diagnosed with GDM using these criteria and determined whether the IADPSG criteria is suitable in our population.

Methods

This randomized controlled trial was conducted at our antenatal clinic involving 520 patients from 1st February 2015 until 30th September 2017. They were randomized into the WHO and the IADPSG groups. All eligible women underwent a standard oral glucose tolerance test with 75 g glucose, their fasting and 2 h post prandial glucose levels were taken. The primary outcome was the prevalence of GDM. The secondary outcomes were the incidence of primary cesarean section, gestational hypertension or preeclampsia, preterm delivery <37 weeks, fetal macrosomia, neonatal hypoglycemia and shoulder dystocia or birth injury.

Results

The prevalence of GDM in both groups were similar (37.9% vs. 38.6%). GDM women in the WHO group had a significantly higher incidence of gestational hypertension or preeclampsia (p = 0.004) and neonatal hypoglycemia (p = 0.042). In contrast, GDM women in the IADPSG group had a significantly higher incidence of fetal macrosomia (p = 0.027) and cesarean section (p = 0.012).

Conclusion

The IADPSG diagnostic criteria for GDM may not be suitable for use in our population as it resulted in women being diagnosed later and being undertreated, thus leading to adverse maternal and neonatal outcomes.
Generator Coherency Using Zolotarev Polynomial Based Filter Bank and Principal Component Analysis
Authors: Mandadi Kalyani , Kalyan Kumar B.
Published: February 2018

A method is proposed to identify the generators participating in an inter-area mode and the coherent generators by analyzing the discrete signals from phasor measurement units (PMU). In the present work, Zolotarev polynomial based filter bank (ZPBFB) is adopted to decompose the measured signals into monocomponents for modal frequency and damping. ZPBFB is preferred due to the narrow bandwidth of 0.1 Hz and hence closely spaced modes can be distinguished. All the generator speed signals are analysed with ZPBFB to identify the generators participating in an inter-area mode. Principal component analysis (PCA) is widely used for clustering sampled data. It is proposed in the present work to apply PCA on the decomposed signals, obtained from ZPBFB, of those generators participating in an inter-area mode for generator coherency. The efficacy of the proposed method is demonstrated on IEEE two-area test system, 16-machine, 68-bus system and on real time signals recorded by wide area frequency measurement system (WAFMS) in India on November 30, 2011. The detailed simulation results are presented. The performance of the proposed method is compared with small signal stability analysis and wavelet phase difference (WPD) approach.
Effect of prenatal recommendations of Traditional Persian Medicine on obstetric outcomes: a randomized clinical trial
Authors: Keshavarz Mansoor , Kashanian Maryam , Bioos Soodabeh , Vazani Yasaman
Published: February 2018

Background

Traditional Persian Medicine (TPM) is an ancient medical system that provides suggestions to improve the health of mothers and children during pregnancy and labor. Persian physicians believed that these instructions made labor easier, safer, and less painful.

Methods

The present randomized clinical trial was conducted among women at 33–38 weeks of pregnancy in Tehran, Iran. TPM instructions consisted of diet, bathing, and application of oil from the 38th week of pregnancy to the onset of labor. The primary outcome was the duration of the active phase of labor.

Results

The mean duration of the active phase was 331.60 ± 151.48 min for the intervention group and 344.40 ± 271.46 min for the control groups, but it was not statistically significant. The active phase was significantly shorter in women who had better compliance (p=0.03). The need for oxytocin augmentation was 53.3% in the control group and 38.5% in the intervention group (p=0.17). The rate of perineal infection was 13% in the control group and 0% in the intervention group (p=0.11).

Conclusions

The active phase was not different in the intervention and control groups, but it was shorter in compliant women. It is possible that prolonged use of these recommendations in combination with a sitz baths and a larger sample size could result in more significant outcomes.
Behavior Analysis of Illegal Fishing in the Gulf of Mexico
Authors: Pala Ali , Zhang Jing , Zhuang Jun , Allen Nathan
Published: February 2018

Illegal fishing activities in the Gulf of Mexico pose a threat to the US national security, as well as damage to the economy. The US Coast Guard (USCG) estimates over 1100 incursions by Mexican fisherman into US regulated waters in the Gulf of Mexico annually. Fishermen enter the water borders to catch red snapper, which is one of the Gulf of Mexico’s signature and most valuable fish. There are a number of academic contributions which have sought to improve the understanding of the problem of illegal fishing, and to try to generate better solutions. In this study, we investigate the relationship between illegal fishing activities and environmental factors with one-year of historical sight, weather, and moon phase data. Descriptive analysis provides some interesting insights such as sight patterns depending on wave height, moon phase, and hours of a day. Also, we develop logistic regression models that shows wave height is negatively correlated with sight occurrences for all sight types. In addition, we oversample the data and develop two pre diction models using logistic regression and k-nearest neighbor algorithm and compare prediction accuracies. The results show that k-nearest neighbor algorithm performs better in most of the cases.
The zlog value as a basis for the standardization of laboratory results
Authors: Hoffmann Georg , Klawonn Frank , Lichtinghagen Ralf , Orth Matthias
Published: February 2018

Background:

With regard to the German E-Health Law of 2016, the German Society for Clinical Chemistry and Laboratory Medicine (DGKL) has been invited to develop a standard procedure for the storage and transmission of laboratory results. We suggest the commonly used z-transformation.

Methods:

This method evaluates by how many standard deviations (SDs) a given result deviates from the mean of the respective reference population. We confirm with real data that laboratory results of healthy individuals can be adjusted to a normal distribution by logarithmic transformation.

Results:

Thus, knowing the lower and upper reference limits LL and UL, one can transform any result x into a zlog value using the following equation:

zlog
=

(log(x)
–
(log(LL)
+
log(UL))/2)·3
.92/(log(UL)

–

log(LL))

$\eqalign{

{\rm{zlog}} = & {\rm{(log(x)}}-{\rm{(log(LL)}} + {\rm{log(UL))/2)\cdot3}}{\rm{.92/(log(UL)}} \cr

-{\bf{ }}{\rm{log(LL))}} \cr} $

The result can easily be interpreted, as its reference interval (RI) is –1.96 to +1.96 by default, and very low or high results yield zlog values around –5 and +5, respectively. For intuitive data presentation, the zlog values may be transformed into a continuous color scale, e.g. from blue via white to orange.

Using the inverse function, any zlog value can then be translated into the theoretical result of an analytical method with another RI:

(1)

x
=

LL

0.5
−
zlog
/
3.92

⋅

UL

0.5
+
zlog
/
3.92

$${\rm{x}} = {\rm{L}}{{\rm{L}}^{0.5 - {\rm{zlog}}/3.92}} \cdot {\rm{U}}{{\rm{L}}^{0.5 + {\rm{zlog}}/3.92}}$$

Conclusions:

Our standardization proposal can easily be put into practice and may effectively contribute to data quality and patient safety in the frame of the German E-health law. We suggest for the future that laboratories should provide the zlog value in addition to the original result, and that the data transmission protocols (e.g. HL7, LDT) should contain a special field for this additional value.
A review of the status of the Western polecatMustela putorius: a neglected and declining species?
Authors: Croose Elizabeth , Duckworth J.W. , Ruette Sandrine , Skumatov Dmitry V. , Kolesnikov Vyacheslav V. , Saveljev Alexander P.
Published: February 2018

The Western polecatMustela putoriushas a widespread European distribution and is currently listed as Least Concern by theIUCN Red List of Threatened Species. Reports are increasing of polecat population declines in several countries, although a paucity of data means population trends are poorly understood. This paper reviews and summarises information on the polecat’s status and range-wide population trends. Information and opinion were gathered for 34 countries, from individuals and organisations studying polecats and from reviewing the literature and national Red Lists. Where trends were identified, the polecat population is known or suspected to be declining in 20 countries, reported to be stable in five countries, stable or increasing in one country, and increasing in two countries. For many countries, data are so limited in quantity or spatial scale, or at risk of bias, that trends could not be identified or confidence in trend assessments is low. The main drivers of polecat decline are poorly understood, but might include habitat degradation; changes in prey availability; competition with invasive carnivores; poisoning; conflict with human interests; harvesting and killing of polecats; and hybridisation. Robust survey methods and systematic monitoring programmes are urgently needed to gather up-to-date data on polecat population trends across the species’ range.
Advocacy under Xi: NPO Strategies to Influence Policy Change
Authors: Teets Jessica , Almen Oscar
Published: February 2018

Under the Hu-Wen administration, scholars analyzed how political opportunity structures (POS) affect the policy influence of NPOs in China, and found that the opportunity structure was relatively more open, especially for NPOs using personal connections. In this article, we focus on changes in the opportunity structure since Xi Jinping came to power after 2012, and find that the more closed political climate has had important consequences for NPO policy advocacy. We identify three strategies that NPOs have used to advocate, such as using the law, media framing, and establishing expert status. While these strategies are not novel, we argue that the weighting has shifted in terms of what leads to success.
Dropping on the Edge: Flexibility and Traffic Confirmation in Onion Routing Protocols
Authors: Rochet Florentin , Pereira Olivier
Published: February 2018

The design of Tor includes a feature that is common to most distributed systems: the protocol is flexible. In particular, the Tor protocol requires nodes to ignore messages that are not understood, in order to guarantee the compatibility with future protocol versions. This paper shows how to exploit this flexibility by proposing two new active attacks: one against onion services and the other against Tor clients.

Our attack against onion services is a new low-cost side-channel guard discovery attack that makes it possible to retrieve the entry node used by an onion service in one day, without injecting any relay in the network. This attack uses the possibility to send dummy cells that are silently dropped by onion services, in accordance with the flexible protocol design, and the possibility to observe those cells by inspecting public bandwidth measurements, which act as a side channel.

Our attack against Tor clients, called the dropmark attack, is an efficient 1-bit conveying active attack that correlates flows. Simulations performed in Shadow show that the attack succeeds with an overwhelming probability and with no noticeable impact on user performance.

Finally, we open the discussion regarding a trade-off between flexibility and security in anonymous communication systems, based on what we learned within the scope of our attacks.
Möbius: Trustless Tumbling for Transaction Privacy
Authors: Meiklejohn Sarah , Mercer Rebekah
Published: February 2018

Cryptocurrencies allow users to securely transfer money without relying on a trusted intermediary, and the transparency of their underlying ledgers also enables public verifiability. This openness, however, comes at a cost to privacy, as even though the pseudonyms users go by are not linked to their real-world identities, all movement of money among these pseudonyms is traceable. In this paper, we present Möbius, an Ethereum-basedtumblerormixing service. Möbius achieves strong notions of anonymity, as even malicious senders cannot identify which pseudonyms belong to the recipients to whom they sent money, and is able to resist denial-of-service attacks. It also achieves a much lower off-chain communication complexity than all existing tumblers, with senders and recipients needing to send only two initial messages in order to engage in an arbitrary number of transactions.
Family and fertility: does kin help influence women’s fertility, and how does this vary worldwide?
Authors: Sear Rebecca
Published: February 2018

Despite the tendency of some academic disciplines to assume that the nuclear family is normative, the family takes a number of different forms cross-culturally. Regardless of family form, family members typically cooperate in raising children. Intergenerational help (from grandparents to parents and children), for example, is a cross-cultural universal. Such cooperation means that the availability of kin may be one salient factor in deciding whether and when to have children. Here I consider the evidence for whether the availability of kin does influence fertility, and whether these relationships vary cross-culturally. I find evidence from middle and lower income populations that the presence of kin does increase fertility, and that these relationships are plausibly driven by cooperation between family members. In higher income contexts, associations between kin and fertility are mixed, and appear particularly sensitive to how kin availability and support is measured. There is some evidence that certain measures of support from kin (such as emotional support or help with childcare) increases the likelihood of subsequent births, but kin support is not always positively associated with fertility. Family matters for fertility, then, though these relationships may be complex and context-specific. Policy needs to take this diversity into account, and should not focus exclusively on the nuclear family model, nor neglect the roles other family members play in reproductive decisions.
Radiometric measurement of lignite coal and its by-products and assessment of the usability of fly ash as raw materials in Turkey
Authors: Turhan Şeref , Gören Elif , Garad Ahmed M.K. , Altıkulaç Aydan , Kurnaz Aslı , Duran Celalettin , Hançerlioğulları Aybaba , Altunal Volkan , Güçkan Veysi , Özdemir Adnan
Published: February 2018

Lignite coal (LC) is a key energy source for electricity generation in Turkey. During lignite burning, huge amounts of fly ash (FA), bottom ash and slag are produced as by-products which contain radionuclides in the natural radioactive series of uranium and thorium, and radioactive potassium. These radionuclides may lead to radiological exposure of workers and the public and cause environmental problems. Therefore, finding diverse uses for the by-products in the construction sector and earthwork applications has considerable economic and environmental importance. In this study, the activity concentrations of 226Ra, 232Th and 40K in and radon emanating power (EP) and radon mass exhalation rate (EXRM) from LC, slag and FA obtained from the Kangal lignite-burning power plant with a power of 457 MWe were measured using gamma-ray spectroscopy. The major chemical components (SiO2, Al2O3, Fe2O3, CaO and MgO) of fly ash samples were analysed using an energy dispersive X-ray fluorescence spectrometer. The annual effective doses received by workers and members of the public were estimated using different scenarios specified in Radiation protection 122. The average activity concentrations of 226Ra, 232Th and 40K in LC, slag and FA samples were 187±21, 16±1 and 99±9 Bq kg−1, 620±18, 41±2 and 330±13 Bq kg−1, and 937±30, 38±2 and 272±17 Bq kg−1, respectively. The average values of EP and EXRM of the lignite, slag and FA samples were 8 %, 7 % and 10 %, and 0.1, 0.3 and 0.7 Bq kg−1 h−1, respectively. The highest average of the total annual effective dose is estimated at 153 μSv for members of the public and 74 μSv for workers, lower than the recommended annual limit of 1000 μSv.
A review on steam-solvent processes for enhanced heavy oil/bitumen recovery
Authors: Fayazi Amir , Kantzas Apostolos
Published: February 2018

Steam injection is widely used for heavy oil and bitumen recovery. The advantage of this process is its high recovery factor and its high oil production rate. However, the high production rate is associated with excessive energy consumption, carbon dioxide generation, and expensive post-production water treatment. Some of these disadvantages are overcome or reduced by the addition of solvent mixtures to steam. The steam-solvent processes are complex oil displacement methods involving simultaneous heat, mass, and fluid transport. These processes are not clearly understood despite their apparent importance to the oil industry. Systematic studies are essential in the design, analysis, and evaluation of the steam-solvent processes as well as in mathematical simulation. These studies provide valuable insights for petroleum engineers to improve the oil recovery efficiency when applied in a reservoir. Results of these processes are scattered in many publications over more than 40 years and are not readily available for most petroleum engineers. The purpose of the paper is to present a review of current knowledge and available data, and to delineate the steam-solvent processes.
Numerical Investigation of Fuel Distribution Effect on Flow and Temperature Field in a Heavy Duty Gas Turbine Combustor
Authors: Deng Xiaowen , Xing Li , Yin Hong , Tian Feng , Zhang Qun
Published: February 2018

Multiple-swirlers structure is commonly adopted for combustion design strategy in heavy duty gas turbine. The multiple-swirlers structure might shorten the flame brush length and reduce emissions. In engineering application, small amount of gas fuel is distributed for non-premixed combustion as a pilot flame while most fuel is supplied to main burner for premixed combustion. The effect of fuel distribution on the flow and temperature field related to the combustor performance is a significant issue. This paper investigates the fuel distribution effect on the combustor performance by adjusting the pilot/main burner fuel percentage. Five pilot fuel distribution schemes are considered including 3 %, 5 %, 7 %, 10 % and 13 %. Altogether five pilot fuel distribution schemes are computed and deliberately examined. The flow field and temperature field are compared, especially on the multiple-swirlers flow field. Computational results show that there is the optimum value for the base load of combustion condition. The pilot fuel percentage curve is calculated to optimize the combustion operation. Under the combustor structure and fuel distribution scheme, the combustion achieves high efficiency with acceptable OTDF and low NOX emission. Besides, the CO emission is also presented.
Photobiomodulation Therapy on Physiological and Performance Parameters During Running Tests: Dose–Response Effects
Authors: Dellagrana Rodolfo A. , Rossato Mateus , Sakugawa Raphael L. , Baroni Bruno M. , Diefenthaeler Fernando
Published: February 2018

Dellagrana, RA, Rossato, M, Sakugawa, RL, Baroni, BM, and Diefenthaeler, F. Photobiomodulation therapy on physiological and performance parameters during running tests: Dose–response effects. J Strength Cond Res 32(10): 2807–2815, 2018—This study was aimed at verifying effects of photobiomodulation therapy (PBMT) with different energy doses (15, 30, and 60 J per site) on physiological and performance parameters during running tests. Fifteen male recreational runners participated in a crossover, randomized, double-blind, and placebo-controlled trial. They performed testing protocol in 5 sessions with different treatments: control, placebo, and PBMT with 15, 30, or 60 J per site (14 sites in each lower limb). Physiological and performance variables were assessed during submaximal (at 8 and 9 km·h−1) and maximal running tests. Photobiomodulation therapy with 30 J significantly improved running economy (RE) at 8 and 9 km·h−1 (3.01%, p=0.008 and 3.03%, p=0.009, respectively), rate of perceived exertion (RPE) at 8 km/h21 (7.86%, p=0.033), velocity at V̇o
2max (3.07%, p= 0.029), peak of velocity (PV) (1.49%, p=0.035), and total time to exhaustion (TTE) (3.41%, p=0.036) compared with placebo. Photobiomodulation therapy with 15 J improved running economy at 9 km/h21 (2.98%, p=0.025), rate of perceived exertion at 8 km/h21 (4.80%, p=0.010), PV (1.33%, p=0.008), total time to exhaustion (3.06%, p=0.008), and total distance (4.01%, p=0.011) compared with the placebo; whereas PBMT with 60 J only increased RE at 9 km/h21 (3.87%, p=0.024) compared with placebo. All PBMT doses positively affected physiological and/or performance parameters; however, magnitude-based inference reported that PBMT applied with 30 J led to more beneficial effects than 15 and 60 J.
Reduced Electromyographic Fatigue Threshold After Performing a Cognitive Fatiguing Task
Authors: Ferris Justine R. , Tomlinson Mary A. , Ward Tayler N. , Pepin Marie E. , Malek Moh H.
Published: February 2018

Ferris, JR, Tomlinson, MA, Ward, TN, Pepin, ME, and Malek, MH. Reduced electromyographic fatigue threshold after performing a cognitive fatiguing task. J Strength Cond Res 35(1): 267–274, 2021—Cognitive fatigue tasks performed before exercise may reduce exercise capacity. The electromyographic fatigue threshold (EMGFT) is the highest exercise intensity that can be maintained without significant increase in the electromyography (EMG) amplitude vs. time relationship. To date, no studies have examined the effect of cognitive fatigue on the estimation of the EMGFT. The purpose of this study, therefore, was to determine whether cognitive fatigue before performing exercise reduces the estimated EMGFT. Eight healthy college-aged men were recruited from a university student population and visited the laboratory on multiple occasions. In a randomized order, subjects performed either the cognitive fatigue task (AX continuous performance test) for 60 minutes on one visit (experimental condition) or watched a video on trains for 60 minutes on the other visit (control condition). After each condition, subjects performed the incremental single-leg knee-extensor ergometry test while the EMG amplitude was recorded from the rectus femoris muscle and heart rate was monitored throughout. Thereafter, the EMGFT was calculated for each subject for each visit and compared using paired samples t-test. For exercise outcomes, there were no significant mean differences for maximal power output between the 2 conditions (control: 51 ± 5 vs. fatigue: 50 ± 3 W), but there was a significant decrease in EMGFT between the 2 conditions (control: 31 ± 3 vs. fatigue: 24 ± 2 W; p = 0.013). Moreover, maximal heart rate was significantly different between the 2 conditions (control: 151 ± 5 vs. fatigue: 132 ± 6; p = 0.027). These results suggest that performing the cognitive fatiguing task reduces the EMGFT with a corresponding reduction in maximal heart rate response.
Self-selected vs. Fixed Repetition Duration: Effects on Number of Repetitions and Muscle Activation in Resistance-Trained Men
Authors: Nóbrega Sanmy Rocha , Barroso Renato , Ugrinowitsch Carlos , da Costa Jean Lucas Fernandes , Alvarez Ieda Fernanda , Barcelos Cintia , Libardi Cleiton Augusto
Published: February 2018

Nóbrega, SR, Barroso, R, Ugrinowitsch, C, da Costa, JLF, Alvarez, IF, Barcelos, C, and Libardi, CA. Self-selected vs. fixed repetition duration: effects on number of repetitions and muscle activation in resistance-trained men. J Strength Cond Res 32(9): 2419–2424, 2018—The aim of this study was to compare the effects of self-selected and fixed repetition duration (RD) on resistance exercise (RE) volume, muscle activation, and time under tension (TUT) per repetition and per session. Twelve resistance-trained men participated in the study. A randomized cross-over design was used and each participant performed 2 high-intensity RE protocols in a balanced order: (a) 3 sets of RE with self-selected RD (SELF); and (b) 3 sets of RE with fixed RD (2-second concentric and 2-second eccentric [FIX]). Muscle activation was assessed through surface electromyography (EMG) of the vastus lateralis and vastus medialis throughout RE sessions. Overall, RE volume was significantly greater for SELF (p = 0.01), whereas TUT per repetition was significantly greater for FIX (p = 0.0001). No significant differences between protocols were detected for TUT per session. Between-protocol comparisons revealed significantly greater EMG amplitude for SELF compared with FIX at S1 (p = 0.01), S2 (p = 0.03), and S3 (p = 0.03). Both SELF and FIX protocols produced significant increases in EMG amplitude from 25 to 100% (p < 0.001) of set completion. Between-protocol comparisons revealed significantly greater EMG amplitude for SELF compared with FIX at 75% (p = 0.03) and 100% (p = 0.01). In conclusion, self-selected RD resulted in greater volume and muscle activation compared with fixed RD in an RE session.
Relationship Between Change of Direction, Speed, and Power in Male and Female National Olympic Team Handball Athletes
Authors: Pereira Lucas A. , Nimphius Sophia , Kobal Ronaldo , Kitamura Katia , Turisco Luiz A.L. , Orsi Rita C. , Cal Abad César C. , Loturco Irineu
Published: February 2018

Pereira, LA, Nimphius, S, Kobal, R, Kitamura, K, Turisco, LAL, Orsi, RC, Cal Abad, CC, and Loturco, I. Relationship between change of direction, speed, and power in male and female National Olympic Team handball athletes. J Strength Cond Res 32(10): 2987–2994, 2018—The aims of this study were to (a) assess the relationship between selected speed- and power-related abilities (determined by 20-m sprint, unloaded countermovement jump [CMJ] and squat jump [SJ], and loaded jump squat [JS]) and performance in 2 distinct change of direction (COD) protocols (Zigzag test and T-test) and (b) determine the magnitude of difference between female and male Brazilian National Olympic Team handball athletes. Fifteen male and 23 female elite handball athletes volunteered to perform the following assessments: SJ and CMJ; Zigzag test and T-test; 20-m sprint with 5-, 10-, and 20-m splits; and mean propulsive power in JS. Pearson's product-moment correlation (p ≤ 0.05) was performed to determine the relationship between the COD tests (Zigzag test and T-test) and speed-power measures (sprint, SJ, CMJ, and JS). The differences between male and female performances were determined using the magnitude-based inference. Moderate to very large significant correlations were observed between both COD tests and the speed-power abilities. Furthermore, male athletes demonstrated likely to almost certainly higher performances than female athletes in all assessed variables. The results of the current study suggest that different speed-power qualities are strongly correlated to the performance obtained in various COD assessments (r values varying from 0.38 to 0.84 and from 0.34 to 0.84 for correlations between speed and power tests with Zigzag test and T-test, respectively). However, the level of these associations can vary greatly, according to the mechanical demands of each respective COD task. Although COD tests may be difficult to implement during competitive seasons, because of the strong correlations presented herein, the regular use of vertical jump tests with these athletes seems to be an effective and applied alternative. Furthermore, it might be inferred that the proper development of loaded and unloaded jump abilities has potential for improving the physical qualities related to COD performance in handball athletes.
Tracking of Time-Dependent Changes in Muscle Hardness After a Full Marathon
Authors: Inami Takayuki , Nakagawa Kento , Yonezu Takahisa , Fukano Mako , Higashihara Ayako , Iizuka Satoshi , Abe Taira , Narita Takaya
Published: February 2018

Inami, T, Nakagawa, K, Yonezu, T, Fukano, M, Higashihara, A, Iizuka, S, Abe, T, and Narita, T. Tracking of time-dependent changes in muscle hardness after a full marathon. J Strength Cond Res 33(12): 3431–3437, 2019—We sought to identify changes in individual muscle hardness after a full marathon and to track time-dependent changes using ultrasound strain elastography (SE). Twenty-one collegiate marathon runners were recruited. Muscle hardness (i.e., strain ratio, SR) was measured using SE for the rectus femoris (RF), vastus lateralis (VL), biceps femoris (BF) long head, tibialis anterior (TA), gastrocnemius medial (GM) head, and soleus (SOL) muscles at the following time points: pre (PRE), immediately post (POST), day-1 (D1), day-3 (D3), and day-8 (D8), after a full marathon. We found that the SR decreased after the full marathon (i.e., the muscle became harder), and that the lowest SR across all measured muscles was observed on D1. Although there was no difference in the magnitude of change in SR between the muscles of the thigh, that of the MG and SOL were significantly larger than that of the TA. Muscle hardness in the vastus lateralis, biceps femoris, and SOL recovered at D8 (i.e., nonsignificant difference from PRE), whereas recovery of rectus femoris and gastrocnemius medial hardness at D8 was not observed. Thus, the degree of change in muscle hardness does not occur uniformly within the lower extremity muscles. In particular, changes in muscle hardness of the TA after a full marathon are small compared with other muscles and time-dependent changes in each muscle vary during recovery. The features of muscle hardness identified in this study will be useful for coaches when mentoring runners on proper forms and for training advisers and therapists who seek to address deficiencies in running.
Tweeting for Nutrition: Feasibility and Efficacy Outcomes of a 6-Week Social Media-Based Nutrition Education Intervention for Student-Athletes
Authors: Coccia Catherine , Fernandes Stephanie M. , Altiti Julinar
Published: February 2018

Coccia, C, Fernandes, SM, and Altiti, J. Tweeting for nutrition: feasibility and efficacy outcomes of a 6-week social media-based nutrition education intervention for student-athletes. J Strength Cond Res 34(7): 2084–2092, 2020—The main objective of this study was to determine the feasibility and efficacy of a social media-based nutrition intervention using Twitter on nutrition knowledge, dietary practices, body mass index (BMI), self-efficacy, and social support among student-athletes. Participants included 50 male and female National Collegiate Athletic Association Division I student-athletes between the ages of 18 and 24 years. Data were collected in October 2014. The study design employed a 6-week social media intervention using Twitter, to increase nutrition knowledge, self-efficacy, social support, and dietary adherence to the recommendations from the Dietary Guidelines for Americans. Descriptive statistics were calculated for all study variables and pre-post differences were assessed using paired t-tests. The results indicate a 6-week nutrition intervention delivered solely through social media resulted in increased nutrition knowledge (t = −2.23; p = 0.035), reduced fat intake (t = −1.57; p = 0.13), and decreased BMI (t = 2.32; p = 0.027) in student-athletes. In conclusion, social media-based nutrition education may provide university-based strength and conditioning coaches and other sports practitioners with a tool for widespread and timely access to students to facilitate healthy dietary behaviors.
Using Perceptual and Neuromuscular Responses to Estimate Mechanical Changes During Continuous Sets in the Bench Press
Authors: Chapman Mark , Larumbe-Zabala Eneko , Goss-Sampson Mark , Triplett N. Travis , Naclerio Fernando
Published: February 2018

Chapman, M, Larumbe-Zabala, E, Gosss-Sampson, M, Triplett, NT, and Naclerio, F. Using perceptual and neuromuscular responses to estimate mechanical changes during continuous sets in the bench press. J Strength Cond Res 33(10): 2722–2732, 2019—This study analyzed the effectiveness of the OMNI-RES (0–10) and the electromyographic signal for monitoring changes in the movement velocity during a set to muscular failure performed with different relative loads in the bench press (BP) exercise. Ten males (30.8 ± 5.7 years) were evaluated on 8 separate days with 48 hours of rest between sessions. After determining the 1 repetition maximum value, participants performed 7 sets to failure with the following relative loads ranges: 30 < 40%, 40 < 50%, 50 < 60%, 60 < 70%, 70 < 80%, 80 < 90%, and >90%. The mean accelerative velocity (MAV), the rating of perceived exertion (RPE), and the normalized root-mean-square (N-RMS) signal from the anterior deltoids were measured for every repetition of each set. The RPE expressed after the first repetition and when the maximum value of MAV was achieved over the sets was lower (p < 0.001, d > 0.80) than the RPE associated with a 10% drop in MAV and at failure. Furthermore, the initial RPE was useful to distinguish different loading zones between the light relative loads (30 < 40% vs. 40 < 50% vs. 50 < 60%) and from these 3 zones to the higher relative load ranges (60 to >90%). Similar, but less clear, differences were observed for the N-RMS. In conclusion, apart from differentiating between relative loads, the RPE and in some cases N-RMS can both reflect changes associated with the initial, maximal, 10% drop in movement velocity, and muscular failure during a continuous set in the BP.
Dynamic Balance Evaluation: Reliability and Validity of a Computerized Wobble Board
Authors: Fusco Andrea , Giancotti Giuseppe F. , Fuchs Philip X. , Wagner Herbert , Varalda Carlo , Capranica Laura , Cortis Cristina
Published: February 2018

Fusco, A, Giancotti, GF, Fuchs, PX, Wagner, H, Varalda, C, Capranica, L, and Cortis, C. Dynamic balance evaluation: reliability and validity of a computerized wobble board. J Strength Cond Res 34(6): 1709–1715, 2020—Computerized wobble boards (WBs) are inexpensive, transportable, and user-friendly devices to objectively quantify the dynamic balance performances out of laboratory settings, although it has not been established if they are reliable and valid tools. Therefore, the purpose of this study was to determine the reliability and validity of a computerized WB. Thirty-nine (18 females and 21 males) young adults (age: 23.3 ± 2.1 years; body mass: 65.9 ± 1.8 kg; height: 168.2 ± 8.8 cm; leg length: 78.8 ± 5.7 cm; and body mass index: 23.2 ± 2.1 kg·m−2) participated in the study. Subjects were assessed during 3 separate sessions on different days with a 48-hour rest in between. A total number of 2 WB single limb tests and 1 Y Balance Test (YBT) were performed. The WB performance was registered using the proprietary software and represented by the time spent in the target zone, which represented the 0° tilt angle measured by the triaxial accelerometer in the WB. YBT normalized reach distances were recorded for the anterior, posteromedial, and posterolateral directions. Intraclass correlation coefficient, 95% confidence interval, SEM, minimal detectable change, and Bland-Altman plots were used to evaluate intrasession and intersession reliability, whereas Pearson product moment correlation was used to determine concurrent validity. Reliability ranged from fair to excellent, showing acceptable levels of error and low minimal detectable change. However, all correlation coefficients between WB and YBT outcomes were poor. Despite the 2 methods addressing different aspects of balance performance, WB seems to validly serve its purpose and showed good reliability. Therefore, computerized WBs have the potential to become essential devices for dynamic balance assessment.
Self-selected Rest Interval Improves Vertical Jump Postactivation Potentiation
Authors: do Carmo Everton C. , De Souza Eduardo O. , Roschel Hamilton , Kobal Ronaldo , Ramos Henrique , Gil Saulo , Tricoli Valmor
Published: February 2018

do Carmo, EC, De Souza, EO, Roschel, H, Kobal, R, Ramos, H, Gil, S, and Tricoli, V. Self-selected rest interval improves vertical jump postactivation potentiation. J Strength Cond Res 35(1): 91–96, 2021—This study compared the effects of self-selected rest interval (SSRI) and fixed rest interval (FRI) strategies on postactivation potentiation (PAP) in countermovement jump (CMJ) performance. Twelve strength-trained men (age: 25.4 ± 3.6 years; body mass: 78.8 ± 10.5 kg; height: 175 ± 7.0 cm; half-squat 1 repetition maximum: 188.7 ± 33.4 kg) performed 3 experimental conditions: (a) FRI: CMJ test; 4-minute rest interval; 5 repetition maximum (5RM) back squat; 4-minute rest interval; and CMJ test, (b) SSRI: CMJ test; 4-minute rest interval; 5RM back squat; SSRI; and CMJ test, and (c) control: CMJ test; 8-minute rest interval and CMJ test. In SSRI, subjects were instructed to rest until they felt fully recovered and able to exercise at maximal intensity based on the perceived readiness scale. Significant changes in pre-post CMJ performance were observed in the SSRI condition (38.2 ± 4.6 cm vs. 40.5 ± 4.4 cm; p = 0.08; confidence interval [CI]: 0.72–3.82 cm; effect size [ES] = 0.93). There were significant differences in post-CMJ performance when SSRI was compared with FRI (40.5 ± 4.4 cm vs. 37.7 ± 5.1 cm; p = 0.02; CI: 0.43–5.08; ES = 1.13) and control (40.5 ± 4.4 cm vs. 37.4 ± 5.7 cm; p = 0.01; CI: 0.66–5.61; ES = 1.35). The average rest interval length for the SSRI condition was 5:57 ± 2:44 min:sec (CI: 4:24–7:30). Our results suggest that the use of SSRI was an efficient and practical strategy to elicit PAP on CMJ height in strength-trained individuals.
Effects of Myofascial Trigger Point Release on Power and Force Production in the Lower Limb Kinetic Chain
Authors: Devereux Frank , O'Rourke Brian , Byrne Paul J. , Byrne Damien , Kinsella Sharon
Published: February 2018

Devereux, F, O'Rourke, B, Byrne, PJ, Byrne, D, and Kinsella, S. Effects of myofascial trigger point release on power and force production in the lower limb kinetic chain. J Strength Cond Res 33(9): 2453–2463, 2019—The purpose of this study was to first investigate the effects of treating latent myofascial trigger points (MTrPs) in the lower limb kinetic chain with respect to performance during sporting actions, as opposed to the traditional goal of pain management with active MTrPs. The second aim was to investigate the effects of dry needling (DN) on performance parameters over time to establish treatment timeframe guidelines before performance. Forty male athletes were assigned to 4 groups; rectus femoris DN (group 1), medial gastrocnemius DN (group 2), rectus femoris and medial gastrocnemius DN (group 3), and no DN (group 4). Subjects completed 6 sessions; familiarization, baseline, immediately after DN, 48, 72, and 96 hours after intervention. Subjects performed squat jumps at 5 incremental loads and were recorded using the My Jump app (iOS) for jump height, power output, optimal force, and optimal velocity. A between–within subject's analysis of variance was used for statistical analysis. Results showed a significant increase in jump height in group 2 (gastrocnemius muscle only) from immediately after to 48 hours after intervention (p = 0.01); however, no other statistical significance was observed. From 48 hours onward, a trend for improved performance was observed, with jump height, power, and velocity showing trivial increases. This study found improved jump performance from immediately after to 48 hours post-DN of the gastrocnemius muscle only. This study suggests a likely immediate decrease in jump performance after DN, with levels increasing above baseline between 48 and 96 hours, which may have clinical significance.
Effect of a Hamstring Flexibility Program Performed Concurrently During an Elite Canoeist Competition Season
Authors: Álvarez-Yates Tania , García-García Oscar
Published: February 2018

Álvarez-Yates, T and García-García, O. Effect of a hamstring flexibility program performed concurrently during an elite canoeist competition season. J Strength Cond Res 34(3): 838–846, 2020—The aim of this study was to determine the acute effect of an 8-week specific hamstring flexibility training on junior canoeist during the competition season. Sixteen canoeists participated, divided into 3 groups: 5 in experimental group 1 (EG1), 5 in experimental group 2 (EG2), and 6 in a control group. The EG1 underwent a supervised program consisted by simple static stretching, dynamic static stretching, and proprioceptive neuromuscular facilitation (PNF), whereas the EG2 performed a program without PNF and no supervision. Two measurements were performed to analyze the effect on the knee joint range of motion (ROM) and trunk flexion; neuromuscular and contractile properties in biceps femoris (BF) and semitendinosus (ST) muscles; and maximum power and average speed in lower limbs. A mixed-design factorial analysis of variance (p ≤ 0.05) was performed and the effect size was calculated. The results show significant improvements (p ≤ 0.05) in both legs for knee joint ROM and trunk flexion in EG1 (8.9 and 25.5%; 5.7 and 20.9% in the right and left leg, respectively) and EG2 (6.7 and 22%; 3.9 and 24.4%), only EG1 improved muscular stiffness in BF (27.4% left leg) and ST (20.5 and 24.3%), and lateral symmetry in BF (49%) without decreasing average speed in lower limbs. All improvements have a large effect size. In conclusion, it is suggested that a supervised hamstring flexibility program performed concurrently during a canoeist competition season can produce an increase in the knee joint ROM and trunk flexion, without negative repercussions in contractile and neuromuscular capacities, maximum power, and average velocity in lower limbs.