Effect of Lower Body Compression Garments on Hemodynamics in Response to Running Session

Purpose. Compression garments are often worn during exercise and allegedly have ergogenic and/or physiological effects. In this study, we compared hemodynamics and running performance while wearing compression and loose-fit breeches. We hypothesized that in neutral-warm environment compression breeches impair performance by diminishing body cooling via evaporative sweat loss and redistributing blood from active musculature to skin leading to a larger rise in body temperature and prolonging recovery of hemodynamics after exercise. Methods. Changes in hemodynamics (leg blood flow, heart rate, and blood pressure during orthoclinostatic test), calf muscle tissue oxygenation, and skin and core temperatures were measured in response to 30 min running (simulation of aerobic training session) followed by maximal 400 m sprint (evaluation of running performance) in recreationally active females (25.1±4.2 yrs; 63.0±8.6 kg) wearing compression or loose-fit breeches in randomized fashion. Results. Wearing compression breeches resulted in larger skin temperature rise under the garment during exercise and recovery (by about 1°C, P<0.05; statistical power > 85%), while core temperature dynamics and other measured parameters including circulation, running performance, and sensations were similar compared to wearing loose-fit breeches (P>0.05). Conclusion. Compared with loose-fit breeches, compression breeches have neither positive nor negative physiological and performance effects for females running in thermoneutral environment

Moderate muscle cooling induced by single and intermittent/prolonged cold-water immersions differently affects muscle contractile function in young males

Background: We investigated the impact of moderate muscle cooling induced by single and intermittent/prolonged cold-water immersions (CWI) on muscle force and contractility in unfatigued state and during the development of fatigue resulting from electrically induced contractions.Methods: Twelve young males participated in this study consisting of two phases [single phase (SP) followed by intermittent/prolonged phase (IPP)], with both phases including two conditions (i.e., four trials in total) performed randomly: control passive sitting (CON) and cold-water immersions (10°C). SP-CWI included one 45 min-bath (from 15 to 60 min). IPP-CWI included three baths (45 min-bath from 15 to 60 min, and 15 min-baths from 165 to 180 min and from 255 to 270 min), with participants sitting at room temperature the rest of the time until 300 min. Blood pressure and intramuscular (Tmu) temperature were assessed, and neuromuscular testing was performed at baseline and 60 min after baseline during SP, and at baseline, 60, 90, 150 and 300 min after baseline during IPP. A fatiguing protocol (100 electrical stimulations) was performed after the last neuromuscular testing of each trial.Results: In unfatigued state, SP-CWI and IPP-CWI reduced electrically induced torque at 100 Hz (P100) but not at 20 Hz (P20), and increased P20/P100 ratio. The changes from baseline for P100 and P20/P100 ratio were lower in IPP-CWI than SP-CWI. Both cold-water immersion conditions slowed down muscle contraction and relaxation, and reduced maximal isokinetic contraction torque, but the changes from baseline were lower after IPP-CWI than SP-CWI. cold-water immersions did not impair maximal voluntary isometric contraction. During the fatiguing protocol, torque fatigue index and the changes in muscle contractile properties were larger after IPP-CWI than SP-CWI, but were in the same range as after CON conditions. The differences of muscle contractile function between SP-CWI and IPP-CWI were accompanied by a lower reduction of superficial Tmu and a smaller increase in systolic blood pressure after IPP-CWI than SP-CWI.Conclusion: IPP-CWI induces a less pronounced fast-to-slow contractile transition compared to SP-CWI, and this may result from the reduced vasoconstriction response and enhanced blood perfusion of the superficial muscle vessels, which could ultimately limit the reduction of superficial Tmu

Human alpha-actinin-3 genotype association with exercise-induced muscle damage and the repeated-bout effect

Alpha-actinin-3 (ACTN3) is an integral part of the Z line of the sarcomere. The ACTN3 R577X (rs1815739) polymorphism determines the presence or absence of functional ACTN3, which may influence the extent of exercise-induced muscle damage. This study aimed to compare the impact of, and recovery from, muscle-damaging eccentric exercise on subjects with or without functional ACTN3. Seventeen young men (20-33 years old), homozygous for the R (n = 9) or X (n = 8) alleles, performed two bouts of stretch-shortening exercise (50 drop jumps) two weeks apart. Muscle soreness, plasma creatine kinase (CK) activity, jump height, maximal voluntary isometric torque (MVC), peak concentric isokinetic torque (IT), and electrically stimulated knee extension torques at 20 and 100 Hz were measured at baseline and at a number of time points up to 14 days after each bout. There were no significant baseline differences between the groups. However, significant time point &times; genotype interactions were observed for MVC (p = 0.021) and IT (p = 0.011) for the immediate effect of eccentric exercise in bout 1. The RR group showed greater voluntary force decrements (RR vs. XX: MVC, -33.3% vs. -24.5%; IT, -35.9% vs. -23.2%) and slower recovery. A repeated-bout effect was clearly observed, but there were no differences by genotype group. The ACTN3 genotype modulates the response of muscle function to plyometric jumping exercise, although the differences are modest. The ACTN3 genotype does not influence the clearly observed repeated-bout effect; however, XX homozygotes recover baseline voluntary torque values faster and thus may be able to undertake more frequent training sessions

Skeletal muscle PGC-1α1 reroutes kynurenine metabolism to increase energy efficiency and fatigue-resistance

The coactivator PGC-1α1 is activated by exercise training in skeletal muscle and promotes fatigue-resistance. In exercised muscle, PGC-1α1 enhances the expression of kynurenine aminotransferases (Kats), which convert kynurenine into kynurenic acid. This reduces kynurenine-associated neurotoxicity and generates glutamate as a byproduct. Here, we show that PGC-1α1 elevates aspartate and glutamate levels and increases the expression of glycolysis and malate-aspartate shuttle (MAS) genes. These interconnected processes improve energy utilization and transfer fuel-derived electrons to mitochondrial respiration. This PGC-1α1-dependent mechanism allows trained muscle to use kynurenine metabolism to increase the bioenergetic efficiency of glucose oxidation. Kat inhibition with carbidopa impairs aspartate biosynthesis, mitochondrial respiration, and reduces exercise performance and muscle force in mice. Our findings show that PGC-1α1 activates the MAS in skeletal muscle, supported by kynurenine catabolism, as part of the adaptations to endurance exercise. This crosstalk between kynurenine metabolism and the MAS may have important physiological and clinical implications

Effects of acute noxious heat exposure on the attention required by tasks of three levels of difficulty in young healthy men

Background: This article discusses the current knowledge on the effects of heat stress on cognitive abilities. Whole-body hyperthermia (WBH) has a negative effect on mental performance. In this study, we investigated whether short-term whole-body immersion in water at 45°C (HWI-45°C), which induces a strong neurotransmitter and temperature flux without inducing whole-body hyperthermia, would impair mental performance in humans. Methods: Fourteen men (aged 25±6 years) were enrolled in this study and participated in three experiments: (i) a brief (5-min) immersion of the whole body in 37°C water (WI-37°C); (ii) a brief (5-min) immersion of the whole body in 45°C water (HWI-45°C); and (iii) a control trial in a thermoneutral condition at an ambient temperature of 24°C and 60% relative humidity. Before and after immersion, cognitive performance was tested. All tests were performed in a quiet and semi-darkened laboratory. Results: Baseline simple, 2-choice and procedural reaction time and percentage of correct answers did not differ significantly across all trials. 2-choice reaction time was reduced (i.e. faster reaction) only after immersion to 37°C water. Interestingly, only whole-body immersion to 45°C was a sufficient trigger to reduce procedural reaction time. Conclusion: young healthy men do not deteriorate in response to whole-body hot water immersion for a short duration. By contrast, we here show faster reaction time in procedural reaction task, which was the most difficult of the three to perform. Keywords: Heat stress, hot water immersion, cognitive performance

Sex differences in reliability of tests to assess cognitive function

Background. The purpose of this study was to identify whether the learning effect, fatigue, motivation, effort and/or sex-specific neural, physiological and morphological factors influenced the results of the test–retest reliability of tests to assess cognitive function. Methods. The sample included ten men (age 21.2 .4 years; body mass 79.5 .3 kg) and ten women (age 22.0 years; body mass 60.0 0.0 kg). Participants accomplished six tests (three for memory and three for attention) four times, i.e. two times (with 24 hours’ break) on successive days (teaching) and two times (with 48 hours’ break) on the third and fifth days (re-testing to assess the reliability). The reliability was assessed by calculating the average of the population, standard deviation, and intraclass correlation coefficient (ICC). Results. In males and females, measurements of attention function were highly reliable over time (ICC .84). The ICCs for volume of spatial memory were above .79, for memory of even number recognition above .57 for both genders and for memory of figure recognition .00 for males and .79 for females. Conclusion. In young healthy males and females, measurements of attention function were highly reliable over time. Meanwhile, reliability for volume of spatial memory was good/high for both sexes, but reliability of memory for even number recognition was insufficient for both sexes and results from memory of figure recognition showed good reliability for women and insufficient reliability for men

Sex-related differences in attention and memory

Background and objectives: The sex differences and similarities in cognitive abilities is a continuing topic of major interest. Besides, the influences of trends over time and possible effects of sex steroid and assessment time on cognition have expanded the necessity to reevaluate differences between men and women. Therefore, the aim of this study was to compare cognitive performance between men and women in a strongly controlled experiment. Materials and methods: In total, 28 men and 25 women were investigated. Variables of body temperature and heart rate were assessed. A cognitive test battery was used to assess attention (visual search, unpredictable task switching as well as complex visual search and predictable task switching tests) and memory (forced visual memory, forward digit span and free recall test). Results: The differences in heart rate and body temperatures between men and women were not significant. There were no differences in the mean values of attention and memory abilities between men and women. Coefficients of variation of unpredictable task switching response and forward digit span were lower (P < 0.05) in men. Coefficients of variation positively correlated (P < 0.05) with attention task incorrect response and negatively correlated (P < 0.05) with correct answers in the memory task. Conclusions: Current study showed no sex differences in the mean values of cognition, whereas higher intra-individual variability of short-term memory and attention switching was identified in women, indicating that their performance was lower on these cognitive abilities

Maldos terapija slaugant ligonius benediktiškoje bendruomenėje arba Maldos terapijos ir psichoterapijos skirtingumai ligonių slaugoje

Katalikų teologijos fakultetasLietuvos kūno kultūros akademijaVytauto Didžiojo universiteta

Knee extensors force output dependence on oscillation stability fluctuation at different body temperatures

Tyrimo tikslas – nustatyti kelio tiesiamųjų raumenų jėgos svyravimo priklausomybę nuo temperatūros atliekant MVJ 2 min. Tiriamieji – sveiki fiziškai aktyvūs vyrai (n = 10), 21,6 ± 2,6 metų amžiaus, 81,1 ± 9,9 kg kūno masės, 183,2 ± 7,7 cm ūgio. Buvo atliekami trys tyrimai – vienas kontrolinis tyrimas ir du eksperimentiniai – šaldymo ir šildymo tyrimai. Eksperimentinis nuo kontrolinio skyrėsi pasyviu koju pašildymu (tiriamieji 45 min sėdėjo panirę iki dubens šiltoje vonioje, kurios vandens temperatūra buvo 44 ± 1 oC) ar pašaldymu (tiriamieji kojas du kartus po 15 min, darydami 10 min pertrauką, panardino į šaltą vonią, kurios vandens temperatūra buvo 15 ± 1ºC). Maksimalus valingosios jėgos krūvis tęsėsi 120 sekundžių (MVJ 2 min), kas 15 sekundžių raumuo buvo stimuliuojamas elektros impulsais – stimuliacijos trukmė 250 ms, dažnis 100 Hz, įtampos dydis 85–105V. Atsigavimas buvo registruojamas praėjus 15 sekundžių ir 5 minutėms nuo krūvio pabaigos. Registruotas raumenų MVJ momentas (N·m) ir raumenų valingo aktyvinimo laipsnis (VA proc.). Izometrinės jėgos signalo svyravimo reguliarumui nustatyti apskaičiuota imties entropija (IE). Nustatyta, kad pasyvaus šildymo metu sukelta tiriamųjų hipertermija, rektalinė kūno temperatūra vidutiniškai padidėjo nuo 37,35 ± 0,32 iki 39,31 ± 0,31oC (p 0,05). MVJ ir IE krūvio pabaigoje visų tyrimų metu sumažėjo reikšmingai (p 0,05). Vadinasi, pasyvus kojų šildymas, kurio metu tiriamiesiems buvo sukelta hipertermija, padidino raumenų izometrinės maksimaliosios valingosios jėgos nuovargį, valingo aktyvinimo laipsnį ir imties entropijos rodiklį, o šaldymas, priešingai, sumažino raumenų izometrinės maksimaliosios valingosios jėgos nuovargį, valingo aktyvinimo laipsnį ir imties entropijos rodiklį.The aim of the research was to determine knee extensors force output dependence on oscillation stability fluctuation at different body temperatures. Methods of the study. The object of the study were healthy men who are active physically (n = 10) (age – 21.6 ± 2.6 years old, weight — 81.1 ± 9.9 kg, height – 183.2 ± 7.7 cm). Three tests were carried out. One was control, the other two were experimental. The experimental test differed from the control one in a passive warming (the subjects legs were immersed in a warm water-bath for 45 minutes; the temperature of the water was – 44 ± 1oC) and cooling (the subjects’ legs were immersed in a water-bath at the temperature of 15 ± 1oC (this was done twice for 15 min with an interval of 10 min)). The load of maximum voluntary contraction (MVC – 2 min) lasted for 120 seconds, when stretching one of their legs by a knee joint at a 60o fixed angle (isokinetic dynamometer, Biodex), every 15 seconds the muscle was stimulated by electrical impulses — the duration of the stimulation was 250 ms, the frequency was 100 Hz, and the voltage was 85—105 V. We registered themoment of MVC (N*m) and the degree of voluntary activation of muscles (VA%). In order to evaluate the muscle isometric force output oscillation stability fluctuation sample entropy were measured. Results and discussion. After passive warming rectal temperature increased from 37.35 ± 0.32 to 39.31 ± 0.31 oC (p 0.05). At the end of the load at all test MVC and sample entropy value decreased significantly (p 0.05). The main conclusion. The results showed that the passive warming increased the fatigue of MVC, level of VA % and index of sample entropy, whenever passive cooling conversely, reduced the fatigue of MVC, level of VA% and index of sample entropy

Exposure to acute noxious heat evokes a cardiorespiratory shock response in humans

Background: Noxious acute cold stimuli cause cold shock via the sympathetic nervous system. However, no studies have investigated respiratory “heat shock” in response to noxious acute heat stimuli (≥ 42 °C). Methods: In the present study, we examined whether short-duration whole-body immersion (for 5 min) in noxious hot water (45 °C) is a sufficient stimulus to induce a respiratory acute shock response. Results and conclusion: Our results indicate that short-duration whole-body immersion in noxious 45 °C water produces a significantly greater body temperature, heart rate, and perceptual and respiratory strain than immersion in innocuous warm 37 °C water (p < .05). The initial first minute of hot water immersion (HWI) at 45 °C (vs. immersion at 37 °C) caused a cardiorespiratory shock response, which manifested as acute hyperventilation, and increased ventilatory tidal volume, respiratory exchange ratio, and heart rate (p < .05). Adjustment to this initial respiratory heat shock response within the first minute of immersion was observed as compared with remaining HWI time (1–5 min). Intriguingly, the time-course kinetics of breathing frequency, oxygen uptake, and carbon dioxide washout did not differ between whole-body immersion at 37 °C and immersion at 45 °C, but were higher than in control thermoneutral conditions of an empty bath (p < .05). This may be because of events initiated not only by the water temperature but also by the change in the hydrostatic pressure acting upon the body when immersed in the water bath