Endurance Stress Research Articles

Relation of synthesis and fatigue property in elastic soft materials

Fatigue has long been studied for many materials, but many aspects are not well understood. Our recent study of the distinct roles of crosslinks and entanglements in the synthesis-property relation of a polymer network under monotonic load leads to a fundamental question: how do crosslinks and entanglements affect the synthesis-property relation of a polymer network under cyclic load? Here we study the relation of synthesis and fatigue property of elastic soft materials without precut cracks. We prepare polyacrylamide hydrogels by free radical polymerization as a model system, and swell the hydrogels in water to equilibrium or to a certain amount of polymer content. The synthesis parameters include the crosslinker-to-monomer molar ratio and the water-to-monomer molar ratio in the precursor, as well as the polymer content in the hydrogel. Three series of hydrogels are prepared. For each hydrogel, the stress-stretch curve under cyclic stretch of various amplitudes and the number of cycles to rupture are measured, giving four properties: fatigue life, endurance stretch, endurance stress, and endurance work. When the crosslinker-to-monomer molar ratio in the precursor is high, the degree of network imperfection on average is low. When the water-to-monomer molar ratio in the precursor is low, the number of entanglements per polymer segment on average is large. We show that crosslinks decrease the susceptibility to fatigue and entanglements increase the endurance stress. By contrast, both crosslinks and entanglements negligibly affect the endurance stretch and the endurance work.

Investigating the deformation and microstructural evolution of laser powder-bed fusion of Hastelloy X during high temperature fatigue loading

This study investigates the fatigue behaviour of samples made by laser powder-bed fusion of Hastelloy X (LPBF-HX) with as-built and machined surface conditions at 700 °C under fully reversed strain-controlled cyclic loading. Samples with both surface conditions exhibited initially cyclic hardening followed by cyclic softening under large strain amplitude testing, where a slight continuous hardening was observed for tests with smaller strain amplitudes. The samples with machined surfaces showed longer endurance and higher stress ranges than those with as-built surfaces. Post-fatigue-test EBSD analysis showed the formation of the Goss texture and extensive local strain accumulation in the samples tested under high strain amplitude at 700 °C. Fractography investigations revealed that early crack initiation in the samples with as-built surfaces was from stress concentrations induced by valleys on the rough surface. No evidence of crack initiation induced by pre-existing defects was observed in the machined samples, and the excessive slip activity at the surface was found to be responsible for the crack initiation.

Motivation of Marathon and Ultra-Marathon Runners. A Narrative Review.

This narrative review study seeks to consolidate the existing knowledge on motivational factors that influence marathon and ultramarathon runners. The primary aim is to collect and summarize the understanding of the factors that drive both marathon and ultramarathon runners. Furthermore the review seeks to explore how variables like gender, age and experience impact motivational drivers within these running communities to highlight the intricate nature of factors, in endurance running and stress the significance of tailored training approaches and community backing to enhance participation and achievement. The study aimed to thoroughly review research papers using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework. After the evaluation of 302 publications that could potentially be relevant, 61 papers were selected for inclusion in the review. The investigation uncovers unique motivating patterns within these endurance sports communities. The desire for good health, physical fitness, and social interaction drives marathon runners. Their motivations develop as they train and become more involved in the running community. On the other hand, ultramarathon runners are motivated by internal psychological variables like self-esteem and personal exploration, which are significantly shaped by the ultramarathon community's impact on their identity and running approach. Additional research indicates that gender, age, and experience affect the motivational elements in both groups differently. Specifically, experienced ultramarathon runners prioritize personal achievements and health more than time. This review underscores the intricacy of motivating elements in endurance running, highlighting the necessity for tailored methodologies in training and communal assistance to cultivate involvement and achievement.

Reliability and Validity of the Korean Version of the Brief Resilience Scale.

: To translate the Brief Resilience Scale into Korean and evaluate its reliability and validity. : To investigate the factor structure of the Brief Resilience Scale, we examined a two-factor model comprising positively and negatively worded items. Congruent and divergent validity of the Brief Resilience Scale were investigated using correlation analysis between the Brief Resilience Scale and resilience, depression, and perceived stress. By conducting an analysis of variance among groups classified by suicidality (no suicidality, only suicidal ideation, and suicidal ideation or suicidal plan groups), we evaluated how well the Brief Resilience Scale could detect people with a high risk of suicide. : Confirmatory factor analysis results supported the construct validity of the Brief Resilience Scale using a two-factor model. Cronbach's alpha (0.91) and McDonald's omega (0.91) scores indicated high internal consistency. Correlation analysis showed that the Brief Resilience Scale scores were strongly associated with a questionnaire evaluating resilience, depression, and perceived stress. Analysis of variance and post-hoc tests showed that he Brief Resilience Scale scores were highest in the no suicidality group (p ＜ 0.001). : The Korean version of the Brief Resilience Scale is a valid and reliable instrument for evaluating resilience as the capacity to recover from adversity and endure obstacles or stress. This study also provides important evidence regarding the sensitivity of the Brief Resilience Scale to suicidal risk.

Oxygen vacancy contributions to the electrical stress response and endurance of ferroelectric hafnium zirconium oxide thin films

Despite its scalability and CMOS process compatibility, the limited endurance and sub-optimal stress response of ferroelectric Zr-substituted hafnia [(Hf,Zr)O2] have been one of the key impediments toward its integration into practical device and technology applications. Here, using electrical measurements complemented by photoluminescence spectroscopy, we investigate the underlying mechanisms behind this behavior in 10 nm thick W/Hf0.5Zr0.5O2/W capacitors. Analyzing the evolution of leakage current with stress cycles and the spectroscopic response of the stress-induced leakage current, we attribute the behavior to defect levels, which lie at 0.6 eV from the conduction band edge of the ferroelectric. Photoluminescence spectroscopy, in turn, further corroborates the defect level's position within the bandgap while enabling its attribution to the presence of oxygen vacancies. This work helps to identify oxygen vacancies as the key factor responsible for the degraded endurance and stress response in (Hf,Zr)O2 and subsequently motivates the exploration of methods to reduce the oxygen vacancy concentrations without destabilizing the ferroelectric orthorhombic phase.

Plant Growth-Promoting Bacterial Consoprtia as a Strategy Towards Crop Growth and Fitness of Little Millet (Panicum sumatranse L.)

Little millet, a minor cereal cultivated in semi-arid regions of India, is renowned for its nutraceutical properties. The endophytic plant growth-promoting bacterial (PGPB) communities help crop plants increase growth and health, endure stress tolerance, and enhance nutrient availability. Seed biotiztion with these endophytic PGPBs can facilitate the host plant to develop a defense against pathogens and challenging environments. Thus the present study aimed to biotize the little millet seeds (var. ATL1) with PGPBs, viz., Bacillus albus LRS2, Alcaligenes faecalis LSB6, Bacillus amyloliquefaciens LAS10 and Bacillus velezensis LLB10 and to evaluate their efficiency by developing as a consortia of these isolates for improved plant growth and development. The seeds were biotized with all the strains individually and as consortia to evaluate their plant growth attributes in vitro and in vivo. The results showed significant differences in vegetative growth parameters and yield attributes compared with the control over consortia biotized seeds. During the panicle initiation stage (27 DAS), the shoot length (59.2, cm), root length (13.9 cm), total plant biomass (1.46 g), number of productive tillers plant-1 (5), panicle length (13.2 cm) and 1000 grain weight (5.12 g), grain yield plant-1 (28.45 g), straw yield (36.21 g) registered more in consortia biotized plants compared to non-biotized plant maintained as control. Thus, the present study confirmed that the inoculation of little millet seeds with the Consortia of indigenous strains could promote plant growth and productivity. Further, the Vol 110|10-12 inoculant can be recommended as a novel bio-inoculant for enhancing crop health and sustainable production in little millet.

Influence of R-Ratio on Fatigue of Aluminum Bonding Wires

Bonding wires made of aluminum are the most used materials for the transmission of electrical signals in power electronic devices. During operation, different cyclic mechanical and thermal stresses can lead to fatigue loads and a failure of the bonding wires. A prediction or prevention of the wire failure is not yet possible by design for all cases. The following work presents meaningful fatigue tests in small wire dimensions and investigates the influence of the R-ratio on the lifetime of two different aluminum wires with a diameter of 300 µm each. The experiments show very reproducible fatigue results with ductile failure behavior. The endurable stress amplitude decreases linearly with an increasing stress ratio, which can be displayed by a Smith diagram, even though the applied maximum stresses exceed the initial yield stresses determined by tensile tests. A scaling of the fatigue results by the tensile strength indicates that the fatigue level is significantly influenced by the strength of the material. Due to the very consistent findings, the development of a generalized fatigue model for predicting the lifetime of bonding wires with an arbitrary loading situation seems to be possible and will be further investigated.

Hotspot testing of glass/backsheet and glass/glass PV modules pre-stressed in extended thermal cycling

This paper investigates the effect of hotspot (HS) stress endurance of two of the latest designs of monocrystalline modules: a half-cell glass/backsheet (G/B) module and a full-cell glass/glass (G/G) module. These modules have already been pre-stressed in extended thermal cycling with 600 cycles per the IEC 61215 standard to represent field-stressed modules. This study differs from the other conventional studies wherein only fresh modules are subjected to hotspot endurance stress. The G/G module reached a maximum temperature of approximately 200 °C at a cell shading of 25 %, 55 °C higher than the maximum hotspot temperature of 145 °C in the G/B module. A significant burn mark, without glass shattering, was observed in the hotspot-stressed cell of the G/G module due to the current mismatch induced by partial shading. Most of the cells in the G/G module appear to be severely damaged (severe dark areas), as observed in the electroluminescence (EL) image, while the dark regions were rarely present in the G/B module. The EL image also illustrates multiple cell cracks that resist current flow and eventually contribute to the full-cell module degradation. About 8.3 % degradation in maximum power was observed for the G/G module and 1.3 % for the G/B module after the sequential stress tests. The lower degradation in the G/B module can potentially be attributed to its design, which comprises of two parallel strings, each having 72-half-cells and benefits from lower heat dissipation. This indicates that the half-cell design could potentially minimize the hotspot degradation and failures in crystalline-silicon modules.

Evaluation of adaptogenic activity of Neurotip capsules by swimming endurance and chronic stress model

Stress is the disturbed homeostatic condition of the organism, and it is represented by non-specific response of the body to any demand imposed on it. Stress brings various changes in physiological condition of the organism, but various mechanism of the body will counteract to maintain homeostasis. Neurotip capsule is effective Ayurvedic treatment for stress related disorders. Neurotip capsules have unique combination of herbs like Jatamansi, Guduchi, Shankapushpi, Ashwagandha, and Probiotics. These herbs are known to sooth the mind, promote calmness and act as a stress buster. In present research study Neurotip formulation was screened for acute toxicity study and sub chronic oral toxicity study on adult albino mice. Animals were observed for behavioural changes, neurological changes and autonomic profile changes. There was no noticeable toxicity and death observed in animals when treated with highest dose of 5000mg/ kg of the formulation. Neurotip was tested on swimming endurance of mice. The results were compared with standard group treated with Geriforte. Test formulation was evaluated by chronic stress model in rats using Omeprazole as standard drug. Assessment of ulcer induction was done to check adaptogenic potential of Neurotip. Ulcer protection by test formulation was found to be 68.44% showing good antistress effects.

The resilience of pioneer crops in the highlands of Central Asia: Archaeobotanical investigation at the Chap II site in Kyrgyzstan

This paper presents archaeobotanical research results from an occupation horizon of the Chap II site left by the earliest known farming community in the Central Tien Shan mountains in the current territory of Kyrgyzstan. The archaeobotanical samples were recovered from well-defined contexts in domestic waste pits, house floors, fireplaces, and an oven, all of which date to a narrow period of occupation between 2474 and 2162 cal BCE (based on n-14 AMS dates). The archaeobotanical assemblage is dominated by the SW package crops of bread wheat and naked barley. Those are the only species to have progressed further east across the mountain ranges of Central Asia during the earliest wave of crop dispersal. However, other species in small quantities were also identified at the Chap II site, such as T. durum/turgidum and T. carthlicum, possibly glume wheats and hulled barley. Here, we argue that the dominant compact morphotypes seen only in bread wheat and naked barley caryopses hint toward a selection for the specific adaptive traits of cultigens that enabled successful agriculture in high-altitude ecogeographies. Large variations in cereal caryopses size possibly indicate that crops endured stress (e.g., insufficient nutrients, water, or other) during plant development. More research is needed for a better understanding of the developmental plasticity between different crop species and the formation of unique landraces in diverse environmental niches in the past.

Thermo-mechanical and degradation properties of naturally derived biocomposites for prosthesis applications: Analysis of the interface pressure and stress distribution on the developed socket

Nowadays, the reduction of petroleum products has been aggressively studied due to their environmental concerns and for finding alternative synthetic materials for sustainable development. Thus, naturally derived biocomposites have great potential for creating a sustainable economy with reduced environmental pollution. The present study deals in two major parts; first, the fabrication of the knee prosthetic socket from different laminate biocomposites (FFF, KKK, and RRR) and examined their mechanical performance, thermal stability and degradation behaviour. The interface pressure between the developed socket and residual limb has been examined using the F-socket sensor. Second, the output data of experiential tests and measured interface pressure have been used for numerical analysis to examine the equivalent stress, deformation and safety factor of the sockets at different loading conditions (500 N, 700 N and 900 N). The results observed that FFF biocomposites have maximum compressive strength (121.0 6MPa), impact strength (36.86 kJ/m2), and shear strength (28.51 MPa) which is 8.15%, 49.53%, and 58.88% higher than RRR biocomposites and 2.74%, 34.62%, and 39.28% higher compared to KKK biocomposites, respectively. RRR biocomposites recorded higher hardness (68.42) and fatigue endurance stress (82.86 MPa) due to higher brittleness properties. The thermogravimetric analysis and degradation behaviour have been analyzed to examine thermal stability, degradation temperature, and degradation weight loss behaviour of biocomposites. Finally, the stress generation on the developed socket during the gait cycle is much lower than its calculated strength that did not affect the performance of the socket. Therefore, laminated biocomposites can be an alternative biomaterial to plastics and conventional materials due to their lighter weight, higher flexibility, and economical to provide greater comfort to the users for knee prosthesis applications.

The Salzburg 10/7 HIIT shock cycle study: the effects of a 7-day high-intensity interval training shock microcycle with or without additional low-intensity training on endurance performance, well-being, stress and recovery in endurance trained athletes—study protocol of a randomized controlled trial

BackgroundPerforming multiple high-intensity interval training (HIIT) sessions in a compressed period of time (approximately 7–14 days) is called a HIIT shock microcycle (SM) and promises a rapid increase in endurance performance. However, the efficacy of HIIT-SM, as well as knowledge about optimal training volumes during a SM in the endurance-trained population have not been adequately investigated. This study aims to examine the effects of two different types of HIIT-SM (with or without additional low-intensity training (LIT)) compared to a control group (CG) on key endurance performance variables. Moreover, participants are closely monitored for stress, fatigue, recovery, and sleep before, during and after the intervention using innovative biomarkers, questionnaires, and wearable devices.MethodsThis is a study protocol of a randomized controlled trial that includes the results of a pilot participant. Thirty-six endurance trained athletes will be recruited and randomly assigned to either a HIIT-SM (HSM) group, HIIT-SM with additional LIT (HSM + LIT) group or a CG. All participants will be monitored before (9 days), during (7 days), and after (14 days) a 7-day intervention, for a total of 30 days. Participants in both intervention groups will complete 10 HIIT sessions over 7 consecutive days, with an additional 30 min of LIT in the HSM + LIT group. HIIT sessions consist of aerobic HIIT, i.e., 5 × 4 min at 90–95% of maximal heart rate interspersed by recovery periods of 2.5 min. To determine the effects of the intervention, physiological exercise testing, and a 5 km time trial will be conducted before and after the intervention. ResultsThe feasibility study indicates good adherence and performance improvement of the pilot participant. Load monitoring tools, i.e., biomarkers and questionnaires showed increased values during the intervention period, indicating sensitive variables.ConclusionThis study will be the first to examine the effects of different total training volumes of HIIT-SM, especially the combination of LIT and HIIT in the HSM + LIT group. In addition, different assessments to monitor the athletes' load during such an exhaustive training period will allow the identification of load monitoring tools such as innovative biomarkers, questionnaires, and wearable technology. Trial Registration: clinicaltrials.gov, NCT05067426. Registered 05 October 2021—Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT05067426. Protocol Version Issue date: 1 Dec 2021. Original protocol. Authors: TLS, NH.

Effect of different physical stressors on soldier’s psychophysiological response and marksmanship

Shooting impairment may occur whereas there is either central or peripherical fatigue. However, the effects of different physical stressor stimuli on fine motor skills as shooting are yet not fully understood. The present research aimed to analyze the effect of endurance and resisted physical stressors on the psychophysiological response and pistol marksmanship of novel soldiers, and the possible differences in gender and BMI. Variables of heart rate, isometric hand strength, rate of perceived exertion, and pistol marksmanship were analyzed in 56 soldiers in endurance and resisted stress protocols. Isometric hand strength, heart rate, and RPE were significantly higher in both resisted and endurance physical stress protocols than in the basal sample. Gender differences were seen in strength, cardiovascular and RPE values. Also, subjects with larger BMI presented significantly higher isometric hand strength and higher marksmanship in all moments evaluated. We conclude that an endurance stress protocol produced a higher cardiovascular and perceived exertion than a resisted one, not affecting hand strength, shooting heart rate, and marksmanship. Females presented lower hand strength and marksmanship while higher rated of perceived exertion and heart rate during the endurance and resisted stress protocols than males. Overweight participants presented higher heart rates during both physical stress protocols, but higher hand strength and marksmanship while similar shooting heart rates than normal-weight participants

Cellular Photosynthetic Pigment and Structural Change in Festuca arundinacea (Tall Fescue) after Exposure to Acute and Chronic Chromium and Copper Stress

Expanded industrial globalization has resulted in the release of high concentrations of heavy metals into environmental water sources and soils. Phytoremediation may help to remove these heavy metals from contaminated soils. Tall fescue (Festuca arundinacea Shreb.) exhibits phytoremediation potential due to its endurance and high stress tolerances. Here, we report photochemical and structural responses in tall fescue to acute and chronic doses of heavy metals, copper (Cu) and hexavalent chromium (Cr(VI)). Visual signs of stress and decreased photosynthetic yield measurements were detected for both the acute and chronic exposures. To gain insight into stress responses at the cellular level, structural and pigment changes in tall fescue in response to Cu and Cr(VI) stress were assessed with brightfield and confocal fluorescence imaging. While brightfield images showed qualitative changes in plant tissue structure, the quantification of changes were not statistically significant due to high variability between leaf blades. Fluorescence imaging confirmed decreasing total chlorophyll content in tall fescue cross-sections in response to Cr(VI) and Cu exposure. To spectrally separate the closely related chlorophyll pigments (Chl-a, Chl-b, and Chl in photosystem I) and visualize their relative localizations within the plant tissue, hyperspectral confocal fluorescence microscopy was conducted with multivariate curve resolution (MCR) analysis of the data. These results determined that Chl-a and Chl-b were more significantly reduced than Chl associated with photosystem I. Additionally, a new spectral component was identified. A broad autofluorescence (AF) feature appeared in the late stress response of both acute and chronically exposed tall fescue and was localized in globular bodies. While the identity of the broad AF feature remains to be identified, we hypothesize that it may be associated with degraded chlorophyll components in autophagic bodies. If confirmed, this would indicate that autophagy is a stress response to heavy metal exposure in tall fescue.

The effect of vibrations on the mechanical properties of laminations

Abstract This study aims to increase the mechanical properties of the composite material manufactured by the lamination process. In this study, the lamination process will be implemented in two ways, and mechanical properties are compared between the two methods. The first method covers the lamination process under the influence of vacuum pressure only, while in the second method lamination process is achieved by the influence of vacuum pressure and vibrate by shaker device. The results showed that the endurance stress of fatigue increased by 18.18% for the material manufactured by the lamination process under the influence of vibration, while the yield stress and ultimate stress values remained roughly constant for both methods.

Development of non-linear models to evaluate the NiTi SMA spring actuator

The shape memory alloy (SMA) based actuators are replacing huge and bulky actuators because of its ability to provide high work per unit mass and serves as active prismatic joint to develop precise robotic manipulators. It also helps in developing a light weight manipulators with a simple actuation process. Here, the study presents the relationship between the contraction of Nitinol SMA prings and the input variables such as current and time to effectively interpret the behavioural complexity. In addition, the response of two Shape memory alloy springs in series combination has been discussed. The finite element analysis (FEA) of the SMA wire and spring has also been carried out to predict the fatigue life of SMA wire and spring. The result showed that the contraction rate of SMA spring increases with increase in current and vice-versa. Moreover, the range of current is classified based on its significance. The relationship of current, displacement and time parameters, during the actuation of SMA spring, is a second order polynomial regression model. The applied current and time have positive impact on the contractiong rate of SMA. Several polynomial regression models were developed in order to predict the precise amount of spring actuation. This study also predicts the range of current suitable for its actuation based on its application as actuator. The FEA result shows that the SMA springs can have high endurance stress limit which makes it unique as compared to other commercially available actuators. This study enables to predict the rate of contraction and the deflection trend of SMA based actuators for precise positioning applications.

The influence on behavior and physiology of white-feathered end-of-cycle hens during simulated transport

Transportation is a stressful procedure that can alter end-of-cycle hen (EOCH) behavior and physiology. This study (5 × 3 × 2 factorial arrangement) aimed to assess the effects of temperature (T)/relative humidity (RH) (−10°C uncontrolled RH (−10), +21°C 30%RH (21/30), +21°C 80%RH (21/80), +30°C 30%RH (30/30), +30°C 80%RH (30/80)), duration (4, 8, 12 h), and feather cover [well (WF) and poorly-feathered (PF)] on white-feathered EOCH (65–70 wk) behavior and physiology. EOCH (n = 630) from 3 commercial farms were housed for adaptation (3–5 d), fasted (6 h), crated (53 kg/m2), and placed in a climate-controlled chamber. Data collected included chamber and crate conditions, feather condition score, mortality, core body temperature (CBT), behavior, and delta (∆) blood physiology. Analyses were conducted via ANOVA in a randomized complete block design (farm of origin) with significance declared at P ≤ 0.05. PF EOCH had higher mortality than WF hens during cold exposure (−10). EOCH ∆CBT demonstrated a greater (positive) change at 12 h for all T/RH compared to 4 h at 21/30, 21/80, and −10 (negative). Cold exposure (−10) resulted in a higher percentage of time spent shivering and motionless, while heat exposure resulted in a higher percentage of time spent panting for WF EOCH exposed to 30/30 and WF and PF hens exposed to 30/80. Hen ∆glucose had a greater (negative) change at 4 and 12 h for −10 compared to 4 h at 21/30, and all durations for 21/80, 30/30, and 30/80. PF hens exposed to −10 had a greater (positive) change in ∆sodium, ∆hemoglobin, and ∆hematocrit compared to WF birds (negative). The development of metabolic alkalosis was supported by the increase in ∆blood pH over time and the increase in ∆partial pressure of carbon dioxide, ∆bicarbonate, and ∆base excess extracellular fluid during cold exposure (−10). These results indicated that EOCH exposed to heat endured thermal stress while PF hens exposed to cold were unable to cope with cold stress.

Psychophysiological processes, ensuring the achievement of sports results

Objective: to investigate the role of psychophysiological processes in achieving sports results.Materials and methods: the driving force of sports behavior was measured in free­divers, basketball players and athletes, which consisted of motivation to achieve sports results, emotional stress, situational information, hypoxic stability, and physical endurance. Then the sportsmen rotated the pedals of the bicycle ergometer with simultaneous intermittent breath holdings from 20 to 60 s.Results: it has been established that all components of the driving force of behavior are necessary for the sports activity of all groups of sportsmen. For the driving force of free­divers’ behavior, hypoxic stability is of greatest importance (r = 0.59), for basketball players — emotional stress (r = 0.6) and for athletes — emotional stress and situational information (r = 0.71 and 0.58). In addition, hypoxic stability and physical endurance directly affect the final sports result (r = 0.7 and 0.65) in conjunction with the driving force of behavior (r = 0.53).Conclusion: sports result is provided by the driving force behind the behavior of sportsmen. For free­divers, hypoxic stability is of primary importance, for basketball players — physical endurance and emotional stress, and for athletes — the totality of all components of the driving force of behavior.

Continuous Protein Supplementation Reduces Acute Exercise-Induced Stress Markers in Athletes Performing Marathon.

The aim of this study was to determine the changes in endurance performance and metabolic, hormonal, and inflammatory markers induced by endurance stress (marathon race) in a combined strategy of training and dietary protein supplementation. The study was designed as a randomised controlled trial consisting of regular endurance training without and with a daily intake of a soy protein-based supplement over a three-month period in 2 × 15 (10 males and 5 females per group) endurance-trained adults. Body composition (body mass, BMI, and fat mass) was determined, and physical fitness was measured by treadmill ergometry at baseline and after 3 months of intervention; changes in exercise-induced stress and inflammatory markers (CK, myoglobin, interleukin-6, cortisol, and leukocytes) were also determined before and after a marathon competition; eating behaviour was documented before and after intervention by a three-day diet diary. Although no significant influence on endurance performance was observed, the protein supplementation regime reduced the exercise-induced muscle stress response. Furthermore, a protein intake of ≥20% of total energy intake led to a lower-level stress reaction after the marathon race. In conclusion, supplementary protein intake may influence exercise-induced muscle stress reactions by changing cellular metabolism and inflammatory pathways.

A Brief Review of Swimming Endurance and Chronic Stress Model for Evaluation of Adaptogenic activity

Stress is the disturbed homeostatic condition of the organism, and it is represented by non-specific response of the body to any demand imposed on it. Stress brings various changes in physiological condition of the organism, but various mechanism of the body will counteract to maintain homeostasis. In some situations, body’s adaptation to stress is like reward, which is responsible for improvement of body’s performance beyond its capacity. However if organism suffer strong acute or chronic stress, body is unable to maintain homeostasis. Under this condition, various types of diseases and disorders will develop, and even it may lead to death, if it is not managed at proper time. Hazardous stressful situation can be managed by using antistress agent or adaptogen. These agents improve physical and mental working capacity in severe stress circumstances. In different screening models for evaluation of adoptogenic activity, animals are challenged with acute or chronic stress conditions. Various stimulating, stress protective, tonic responses and biochemical markers were measured in evaluation of adoptogenic activity in these animal models.