High-intensity Loading Research Articles

On the Similarity of Dynamic Destructive Processes in Metals of Different Geometry under the Effect of External Impacts with Various Amplitude-Time Characteristics

In this paper, we aimed to establish the similarity of dispersion of various metals at high-intensity loading. Characteristics of the dispersing products and the cascade of arising dissipative structures (the inner surface roughness of the destruction centers, the cascade of the slip bands of the crystal lattice, the cascade of destruction centers, and the roughness of the destruction surface) were quantified on the basis of fractal geometry using the interactive image analysis system (IIAS) package. We numerically simulated destruction in loaded samples using the TIM 3D Lagrangian technique.

PL - 041 Effects of power resistance exercise and feeding on the expression of putative mechanosensing proteins in skeletal muscle of resistance-trained men

Objective Power resistance exercise involves high intensity (load and velocity) dynamic muscular contractions and is frequently performed by athletes to enhance performance via improved muscle function. To investigate the remodelling processes that contribute to improved muscle function, we investigated the expression of putative mechanosensing genes implicated in this process (Kojic et al., 2011): titin-linked Muscle Ankyrin Repeat Protein (MARPs) family CARP, Ankrd 2 and DARP, and the Z-disc associated muscle-LIM protein (MLP) in healthy, resistance-trained men (n = 7) following 90 min of rest (Rest) or power resistance exercise, with (Ex + Meal) or without (Ex only) feeding during recovery.
 Methods Percutaneous needle biopsy samples were obtained from the vastus lateralis of resistance-trained males using local anesthetic (2% Xylocaine), 3 h after performing each of the three experimental trials on separate days.
 Previously, we presented results from this study showing that the mRNA levels of CARP (~15-fold) and MLP (~2.5-fold) were upregulated in human skeletal muscle 3 h post power resistance exercise (Wette et al., 2012). Based on these results, we performed protein analyses on the same muscle samples to determine the protein levels of all MARPs and MLP in whole muscle homogenates after Rest, Ex only and Ex + Meal. To assess whether the exercise elicited a stress response in these resistance-trained individuals, the level of phosphorylated heat shock protein 27 at serine 15 (pHSP27-Ser15) was measured at Rest and 3 h after Ex only and Ex + Meal. The levels of pHSP27-Ser15 are typically upregulated 3 h after eccentric exercise in human skeletal muscle (Frankenberg et al., 2014).
 Results The 90 min exercise session consisted of 180 intermittent muscular contractions at high intensity (70-96% maximal strength). Compared to Rest, there were ~5.8- and 12.6-fold increases in pHSP27-Ser15 levels at 3 h post Ex only and Ex + Meal (both P = 0.049, one-way ANOVA) respectively. CARP protein levels were elevated ~2.7-fold after Ex only (P = 0.049, one-way ANOVA) and ~7.6-fold after Ex + Meal (P = 0.326), due to markedly higher levels (6-40-fold) in three of the seven participants. Pearson correlation analysis revealed a significant positive correlation between the levels of pHSP27-Ser-15 and CARP protein (r = 0.56, P = 0.008). Ankrd 2, DARP and MLP protein levels were unchanged (all P > 0.05) following Ex only and Ex + Meal.
 Conclusions These findings indicate that CARP is highly responsive to increased mechanical loading because the protein levels in skeletal muscle can be substantially increased as early as 3 h after stressful resistance exercise. This suggests a specialised role for CARP protein during the early phases of muscle remodelling that occur as a consequence of performing high intensity resistance exercise.

PL-004 Research on monitoring power endurance training effect of synchronized swimmers

Objective To explore the usage of heart rate and derivative index, such as quick recovery index (QRI) and training impulse (TRIMP), to monitor and evaluate load level at physical training course. With simplified load evaluation program, we can accurately feedback load stress and recovery conditions of the athletes, so as to timely adjust training load and avoid sports fatigue.
 Methods Maximum oxygen uptake is tested to determine maximum heart rate of the athletes, which can be used as the basis for monitoring assessment of physical training load. During training phase, monitoring the variation of the relative index of HR and sleeping conditions of 10 athletes by Firstbeat. The test means was High-intensity interval endurance of climbing machine in 7*20s-20s before and after stage training. The main indexes include of QRI/TRIMP/EPOC/BLa\climbing height. 
 Results It’s shown through monitoring that maximum heart rate of the athletes in the physical training course is up to 200BPM, which prompts high load level during training. Such athletic ability is promoted to satisfy the demands for complex choreography. Characteristics of energy supply for power endurance with high intensity closely agree with physical fitness demand during synchronized swimming competition, which is general performance of strength, speed and endurance. Through comparison of data on testing power endurance of climbing machine in 7*20s-20S before and after training, average climbing height of the athletes is increased from 60.1m/20s to 62.4m/20s with increased range up to 3.8% and blood lactate level is decreased from 10.7mmol/L to 10.5mmol/L in 2 minutes after exercise, which can be regarded as slightly improvement of ability of the athletes for lactate decomposition and fatigue relief, and aerobic capacity of the athletes are improved to a certain degree. After training, heart rate QRI and TRIMP of the athletes are improved slightly. Among them, QRI is significantly improved from 19.6% to 21.6% after stage training, which shows slightly improvement of training quality and recovery capability of the athletes, i.e. adaptive capacity to training load; After physical training, research on monitoring QRI of the athletes during arrangement and relaxation shows that maximum heart rate level without voice guidance is 75.1bpm,which is higher than those with voice guidance 72.9bmp after 5-min quick recovery; QRI of the athletes is 31.9% when voice is used to guide relaxation, which is significantly higher than those without relaxation under voice guidance (QRI is 27.0%); night pressure monitoring unit (BodyGuard2) of Firstbeat is used to monitor sleeping conditions of the athletes. In the initial stage of heavy load training cycle, training load enables athletes to produce a strong stress response, which causes relatively poor sleeping and recovery conditions; with gradual adaptation of the athletes to the training load, in the middle and later stages of the cycle, stress response of the athletes during sleeping almost disappears, and their sleeping quality and recovery conditions are improved significantly. 
 Conclusions Through Power endurance training, lactate elimination capacity of the athletes, i.e. anti-fatigue capacity and quick recovery capability are improved; during quick recovery of the athletes, voice guidance can be used to effectively promote quick recovery of the athletes. Exercise heart rate, TRIMP and QRI can be used to perceptually and rapidly monitor completion of physical training load in a real-time way, Objective to evaluate recovery and sleeping conditions of the athletes, and effectively evaluate high-intensity interval physical training load and training effect.

Palm oil mill secondary effluent (POMSE) treatment via photocatalysis process in presence of ZnO-PEG nanoparticles

Palm oil mill secondary effluent (POMSE) has high colour intensity, turbidity and organic load of biochemical oxygen demand which still not achieved the discharged requirement by department of environment and led to detrimental to the aquatic life. Photocatalysis process is one of the promising method in wastewater treatment due to its advantages. This study reports on the POMSE treatment using photocatalysis process in presence of ZnO-polyethylene glycol (ZnO-PEG) nanoparticles. The characterization results using fourier-transform infrared spectroscopy, X-Ray diffraction and transmission electron microscopy show that there are no impurities present in the samples and presenting the nature and chemical bonds of ZnO-PEG besides having less agglomeration and smaller average in size (25–150 nm) compared to commercial ZnO (25–200 nm). ZnO-PEG nanoparticles have a great potential in degradation of POMSE and this is supported with the results obtained from the experimental works. Four potential factors which are different type of (A) photocatalysts, (B) pH of the POMSE, (C) ZnO-PEG loading and (D) concentration of POMSE were evaluated for the significance design of experiment. It is found that all the main factors were significant, with contributions of (A)66%, (B)73%, (C)84% and (D)84% respectively, to the POMSE degradation. Accordingly, the most favorable condition for the photocatalysis degradation process of POMSE is under pH 6.5 in presence of 0.5 g/L ZnO-PEG for the 50% of POMSE dilution. It is believed that this integrated approach can be implemented in the industry to achieve discharged standard of POMSE and maintain the green environment for future generation.

Collective Projection and Recording of Compact Elements Formed by Implosion of Combined Hemisphere–Cylinder Liners

A method for obtaining and recording high-velocity compact metal elements moving with hypersonic velocities under high-intensity shock loading is developed. A light-gas ballistic device and shadow photography are used for this purpose. Application of a hemisphere–cylinder liner makes it possible to test a shaped charge that steadily forms a compact steel element moving with a velocity approximately equal to 6 km/s. The results of numerical and experimental testing of this projector are given.

Sensorimotor Exercises and Enhanced Trunk Function: A Randomized Controlled Trial.

The aim of this study was to investigate the effect of a 6-week sensorimotor or resistance training on maximum trunk strength and response to sudden, high-intensity loading in athletes.Forty-three healthy, well-trained participants were randomized into sensorimotor (SMT; n=11), resistance training (RT; n=16) and control groups (CG; n=16). Treatment groups received either sensorimotor training (SMT) or resistance training (RT) for 6 weeks, 3 times a week. At baseline and after 6 weeks of intervention, participants' maximum isokinetic strength in trunk rotation and extension was tested (concentric/eccentric 30°/s). In addition, sudden, high-intensity trunk loading was assessed for eccentric extension and rotation, with additional perturbation. Peak torque [Nm] was calculated as the outcome.Interventions showed no significant difference for maximum strength in concentric and eccentric testing (p>0.05). For perturbation compensation, higher peak torque response following SMT (Extension: +24 Nm 95%CI±19 Nm; Rotation: +19 Nm 95%CI±13 Nm) and RT (Extension: +35 Nm 95%CI±16 Nm; Rotation: +5 Nm 95%CI±4 Nm) compared to CG (Extension: -4 Nm 95%CI±16 Nm; Rotation: -2 Nm 95%CI±4 Nm) was present (p<0.05).This study showed that isokinetic strength gains were small, but that significant improvements in high-intensity trunk loading response could be shown for both interventions. Therefore, depending on the individual's preference, therapists have two treatment options to enhance trunk function for back pain prevention.

MODERATE INTENSITY IS A BETTER STIMULUS TO INDUCE QUADRIPECS FEMORIS POWER IN ELDERLY ADULTS

ABSTRACT Introduction: The best strategy for improving knee extensor power, a major functional capacity indicator in older adults, is power training. Nonetheless, the training intensity required to induce optimal gains is yet to be found. Objective: Our purpose was to compare knee extensor peak power responses between low, moderate, and high intensity load conditions (30%, 50% and 70% of 1RM). Methods: Thirteen sedentary elderly women performed six knee extensions in each load condition, calculating knee extensor mechanical work/power output and knee extension peak angular velocity. Results: No difference in peak power was found between the high (207.0 ± 68.1 W) and moderate (206.1 ± 71.6 W) load conditions (p = 0.994), and both had higher values (p ≤0.004) than the low intensity condition (135.6 ± 56.3 W). Conclusion: Moderate load at 50% of 1RM appears to be the preferred strategy for inducing knee extensor power output because in contrast with the high intensity condition, the moderate load yielded higher angular peak velocity, which is also a functional indicator. Level of Evidence ll; Therapeutic studies - Investigating treatment results.

ФУНКЦИОНАЛЬНАЯ ПОДГОТОВКА КАК ЭФФЕКТИВНОЕ СРЕДСТВО АДАПТАЦИИ КУРСАНТОВ И СЛУШАТЕЛЕЙ В ОБРАЗОВАТЕЛЬНЫХ ОРГАНИЗАЦИЯХ МИНИСТЕРСТВА ВНУТРЕННИХ ДЕЛ РОССИЙСКОЙ ФЕДЕРАЦИИ

Aim. The aim of this article is to study the functional state of military students and students of the educational institutions in the system of the Ministry of Internal Affairs. Materials and methods. CrossFit is a multifunctional training of high intensity. The peculiarity of this type of movement activity is that all trainings are conducted according to the pattern with understandable and clear structure. The pattern is based on 3 trainings per week to provide a relatively large amount of high-intensity load within 20 minutes during each training. Each training consists of 3 different elements: metabolic exercises, gymnastics and load exercises. This pattern provider the possibility to acquire new elements and to train effectively 3 energy systems. To estimate the effectiveness of this method, we conducted a pedagogical experiment at the premises of the East-Siberian Institute of the Ministry of Internal Affairs of the Russian Federation. Results. The results obtained allowed us to establish that introduction of CrossFit exercises in the experimental group improved the speed of adaptation processes and effect on functional state of the body in comparison with the control group, which demonstrated decreased functional capacities of the body and unsatisfactory adaptation. Conclusion. The results obtained for the study of the cardiovascular system after the introduction of high-intensity multifunctional exercises CrossFit in the experimental group revealed changes in variation pulsometry reflecting increased effect of the parasympathetic system on heart regulation. There is also an increase in М

Model updating of a dynamic model of a composite steel-concrete railway viaduct based on experimental tests

This paper presents a procedure to obtain the physical properties of the finite-element (FE) model of a railway viaduct, suitable for the estimation of the deck slab’s dynamic response during the passage of trains. This procedure is based on experimental results and involves two phases. The first phase consists in the calibration, using a genetic algorithm, to calculate the optimal values for the most influential physical properties, which maximise the agreement between the experimental modal parameters and the ones provided by the FE model. The experimental modal parameters are determined through a dynamic test under forced random vibration. The second phase consists in the modification of the value of two physical properties, the horizontal stiffness of the supports and the modal damping coefficients. These properties have to be adjusted as they lead to different dynamic performances of the structure, depending on whether the structure is subjected to low intensity ambient vibration actions, or subjected to high intensity loads during the passage of trains. The adjustment is based on the slab’s dynamic response (displacements, strains and accelerations) measured during the passage of real trains.

Structure of U-Zr-Mo alloy shell after explosive loading

This presentation describes investigation of a thick-wall spherical shell 48 mm in diameter from the alloy of uranium with molybdenum and zirconium, which survived after high-intensity explosive loading. Investigation was performed in the meridional section of the shell to obtain qualitative data on hardness and microhardness, metallurgical inclusions, damage, and also material microstructure. Structural changes are observed to widely present in the shell material. The localized damage observed both at R ≈ 12-14 mm and R ≈ 16-18 mm are the first and second converged spalls, respectively. What is more, in the southern sector the first spall was recompacted with the remelting of a large region of the material in the adjacent layers (region with the enhanced hardness for the first spall). Cracks of the second spall in the northern sector were also recompacted almost completely.

Alpine Skiing as Winter-Time High-Intensity Training

To counteract the winter activity deficit, we set out to analyze cardiorespiratory and metabolic responses of two high-intensity training (HIT) protocols during alpine skiing (AS), cross-country skiing (XCS), and indoor cycling (IC) and the effects of sex, age, and fitness level in this comparison. Nineteen healthy subjects (two age and fitness groups, both sexes) performed AS, XCS, and IC with measurements of oxygen uptake (V˙O2), energy expenditure (EE), HR, lactate, blood glucose and rate of perceived exertion, determined during 4 min of continuous HIT (HITc: 90% HRmax for XCS and IC or short turn skiing during AS) or 10-min intermittent HIT [HITint: 5 × 1 min high intensity (>90% HRmax or short turn skiing), 1 min active recovery]. During all three exercise modes and irrespective of HIT protocols, sex, age, and fitness, participants were able to reach exercise intensities >90% HRmax and >84% V˙O2max. In all exercise modes 10-min of HITint with a 10-min postexercise O2 consumption phase resulted in greater mean EE per minute compared to 4-min HITc with 10 min postexercise O2 consumption. When applying the same HIT loading and recovery pattern to all three exercise modes, EE during approximately 1:15 h of AS was equivalent to about 1:00 h of either XCS or IC. Across all exercise modes and HIT protocols, high cardiorespiratory and metabolic responses were achieved regardless of age, sex, or fitness. EE during AS can be maximized by choosing the skiing mode "short turn skiing" in combination with an HITint to prolong the duration of continuous high-intensity loading during each descent. Therefore, all exercise modes and both HIT protocols are applicable and feasible in a broad spectrum of healthy subjects.

Effects of a 20-week high-intensity strength and sprint training program on tibial bone structure and strength in middle-aged and older male sprint athletes: a randomized controlled trial.

High-load, high-speed and impact-type exercise may be an efficient way of improving bone strength even in old age. We evaluated the effects of combined strength and sprint training on indices of bone health in competitive masters athletes, who serve as a group of older people who are likely to be able to participate in vigorous exercise of this kind. Seventy-two men (age 40-85) were randomized into an experimental (EX, n=40) and a control (CTRL, n=32) group. EX participated in a 20-week program combining heavy and explosive strength exercises with sprint training. CTRL maintained their usual, run-based sprint training schedules. Bone structural, strength and densitometric parameters were assessed by peripheral QCT at the distal tibia and tibial midshaft. The intervention had no effects on distal tibia bone traits. At the mid-tibia, the mean difference in the change in cortical thickness (ThCO) in EX compared to CTRL was 2.0% (p=0.007). The changes in structure and strength were more pronounced in the most compliant athletes (training adherence >75%). Compared to CTRL, total and cortical cross-sectional area, ThCO, and the area and density-weighted moments of inertia for the direction of the smallest flexural rigidity (I minA , I minD ) increased in EX by 1.6-3.2% (p=0.023-0.006). Polar mass distribution analysis revealed increased BMC at the anteromedial site, whereas vBMD decreased (p=0.035-0.043). Intensive strength and sprint training improves mid-tibia structure and strength in middle-aged and older male sprint athletes, suggesting that in the presence of high-intensity loading exercise, the adaptability of the bone structure is maintained during aging.

Muscle activation during resistance exercise at 70% and 90% 1-repetition maximum in resistance-trained men.

Muscle activation was investigated during resistance exercise with 2 relatively high-intensity loads. Ten resistance-trained men performed the leg press exercise to repetition failure: a set at 70% of 1-repetition maximum (1RM) and a set at 90% of 1RM. Surface electromyography (EMG) was used to assess peak and mean muscle activation of the vastus lateralis, rectus femoris, and vastus medialis. Peak and mean EMG remained greater at 90% than 70% 1RM across all repetitions (P = 0.03 and P = 0.02, respectively). Main effects for trial were also significant for mean EMG activity of the final common repetitions (P = 0.03) favoring 90% 1RM; however, peak EMG activity was similar during the final common repetitions of the 70% and 90% 1RM sets. Across all repetitions, 90% 1RM appears to produce greater muscle activation during the leg press exercise, but similar peak EMG was observed during the final common repetitions of each set. Muscle Nerve 56: 505-509, 2017.

Influence of 15 km moderate or high-intensity interval military load carriage activity on postural stability

Purpose: The high injury rate among military populations has been associated with frequent load carriage activities. This study aimed to evaluate changes in postural sway responses to moderate and ...

Combination of the optical analyzer technique and multiply photon doppler velocimetry to measure the sound velocities in shock-compressed metals

It is proposed to combine the optical analyzer technique (OAT) and multiply photon Doppler velocimetry (MPDV) in every explosive experiment in order to overcome the reported discrepancies in the sound velocities measured in shock-compressed metals using different techniques. Such a combination is demonstrated to be efficient in explosive experiments with stepped samples of 12Kh18N10Т austenitic stainless steel and high-purity Mg95 magnesium under their shock-wave loading in ranges of 60–120 and 20–30 GPa, respectively. The OAT ensures classical recording of the longitudinal and bulk sound velocities. Depending on the loading intensity, the MPDV technique recorded temporal changes in the velocity of the “sample–indicator” interface or temporal changes in the shock-front velocity in the indicator. These data were used to monitor the parameters of the shock-compressed sample and to determine the instant when the first characteristic of the rarefaction-wave fan overtakes the shock-wave front in the indicator. Within the range of relatively low loads where the indicating fluid remains transparent and acts as a window material, the MPDV registers temporal variations in the velocity of the “sample–indicator material” interface. The OAT ensures reliable registration in the range of high-intensity loads, while the MPDV ensures time-resolved registration of the steady-shock-wave front velocity in the indicator up to the instant of its overtaking by a rarefaction wave. Both techniques are observed to work well in the intermediate range of loads. Combining these techniques enhanced the reliability of the obtained consistent data on the sound velocities in shock-compressed structural materials and also allowed a decreased number of explosive experiments with samples of toxic materials.

Anterior Cruciate Ligament–Derived Stem Cells Transduced With BMP2 Accelerate Graft-Bone Integration After ACL Reconstruction

Background: Strong graft-bone integration is a prerequisite for successful graft remodeling after reconstruction of the anterior cruciate ligament (ACL) using soft tissue grafts. Novel strategies to accelerate soft tissue graft-bone integration are needed to reduce the need for bone-tendon-bone graft harvest, reduce patient convalescence, facilitate rehabilitation, and reduce total recovery time after ACL reconstruction. Hypothesis: The application of ACL-derived stem cells with enhanced expression of bone morphogenetic protein 2 (BMP2) onto soft tissue grafts in the form of cell sheets will both accelerate and improve the quality of graft-bone integration after ACL reconstruction in a rat model. Study Design: Controlled laboratory study. Methods: ACL-derived CD34+ cells were isolated from remnant human ACL tissues, virally transduced to express BMP2, and embedded within cell sheets. In a rat model of ACL injury, bilateral single-bundle ACL reconstructions were performed, in which cell sheets were wrapped around tendon autografts before reconstruction. Four groups containing a total of 48 rats (96 knees) were established (n = 12 rats; 24 knees per group): CD34+BMP2 (100%), CD34+BMP2 (25%), CD34+ (untransduced), and a control group containing no cells. Six rats from each group were euthanized 2 and 4 weeks after surgery, and each graft was harvested for immunohistochemical and histological analyses. The remaining 6 rats in each group were euthanized at 4 and 8 weeks to evaluate in situ tensile load to failure in each femur-graft-tibia complex. Results: In vitro, BMP2 transduction promoted the osteogenic differentiation of ACL-derived CD34+ cells while retaining their intrinsic multipotent capabilities. Osteoblast densities were greatest in the BMP2 (100%) and BMP2 (25%) groups. Bone tunnels in the CD34+BMP2 (100%) and CD34+BMP2 (25%) groups had the smallest cross-sectional areas according to micro–computed tomography analyses. Graft-bone integration occurred most rapidly in the CD34+BMP2 (25%) group. Tensile load to failure was significantly greater in the groups containing stem cells at 4 and 8 weeks after surgery. Tensile strength was greatest in the CD34+BMP2 (100%) group at 4 weeks, and in the CD34+BMP2 (25%) group at 8 weeks. Conclusion: ACL-derived CD34+ cells transduced with BMP2 accelerated graft-bone integration after ACL reconstruction using soft tissue autografts in a rat model, as evidenced by improved histological appearance and graft-bone interface biology along with tensile load to failure at each time point up to 8 weeks after surgery. Clinical Relevance: A primary disadvantage of using soft tissue grafts for ACL reconstruction is the prolonged time required for bony ingrowth, which delays the initiation of midsubstance graft remodeling. The lack of consistent correlation between the appearance of a “healed” ACL on postoperative magnetic resonance imaging and readiness to return to sport results in athletes being released to sport before the graft is ready to handle high-intensity loading. Therefore, it is desirable to identify strategies that accelerate graft-bone integration, which would reduce the time to biologic fixation, improve the reliability of biologic fixation, allow for accelerated rehabilitation, and potentially reduce the incidence of early graft pullout and late midsubstance failure.

Wind and earthquake protection of cable-supported bridges

This paper deals with control strategies for the mitigation of unwanted vibrations in typical medium and long-span cable-supported bridges, aiming to underline general observations and side effects related to the adoption of different control strategies. Two finite-element models of medium and long-span bridges, namely a suspension and a cable-stayed bridge, are developed for simulating the structural response under wind and earthquake excitation. Passive and semi-active control strategies are then implemented in the models for mitigating dynamic effects. Such control schemes have been designed for wind excitation on the suspension bridge, and seismic excitation on the cable-stayed bridge. Attention is initially focused on high-intensity loading conditions, having a low probability of occurrence. The same control strategies and arrangements have then been re-assessed by changing the input intensity; in addition, a cross-check has been performed by addressing earthquake actions on the suspension bridge and wind forces on the cable-stayed bridge. The results have been also analysed in terms of indirect effects, such as fatigue damage.

Effects of heated and humidified high flow gases during high-intensity constant-load exercise on severe COPD patients with ventilatory limitation

IntroductionHigh flow nasal cannula (HFNC) was shown to washout the anatomical dead space, permitting a higher fraction of minute ventilation to participate in gas pulmonary exchanges. Moreover, it is able to guarantee the desired inhaled oxygen fraction (FiO2) even at high level of patient's minute ventilation by minimizing the room air entrainment. The effect of HFNC has never been investigated on stable severe COPD patients in term of endurance capacity with standardised laboratory tests. Method/DesignWe performed, in a randomized crossover study, two constant load exercise tests at the 75% of maximum workload achieved at a previous incremental exercise test on cycle-ergometer: with (HFNC-test) and without HFNC (Control-test). Both constant load tests were fulfilled at the same inhaled oxygen fraction (isoFiO2). ResultsThe endurance time significantly increased in the HFNC-test compared to the Control-test (the mean difference between the two groups was 109 ± 104 s, p < 0.015). At iso-time, HFNC-test showed a better oxygen saturation (95 ± 3% vs 89 ± 3%, respectively, p < 0.005) either in the subgroup of patients who used supplemental oxygen and in the subgroup who did not. Moreover, a significantly lower dyspnea (median of 5.5 vs 10, respectively, p = 0.002) and leg fatigue score (median of 5 vs 9.5, p = 0.002) was recorded at iso-time during HFNC-test. ConclusionHFNC may improve the exercise performance in severe COPD patients with ventilatory limitation. This effect is associated to an improvement of SaO2 and perceived symptoms at iso-time. In a Pulmonary Rehabilitation program HFNC may allow a given high intensity load to be sustained for a longer time with less symptoms.

Biomechanical and physiological effects of two-week sprint interval training in collegiate swimmers

Summary Introduction Interval training with high-intensity loads is recommended for skeletal muscle adaptation in competitive athletes. According to the results of some studies, training intensity, not volume, has greater impact on swimming performance. The aim of present study was to evaluate the effect of 2-week high-intensity, low-volume swimming training with individual passive recovery on both aerobic and anaerobic performance in collegiate swimmers. Summary of facts and results Seven collegiate male swimmers participated in six swimming training sessions within two weeks. Each workout contained repeated high-intensity task. Before and after the training period, kinematics variables were assessed in 25-m maximal swim test and 8 × 25-m swim test with 5-second rest. Aerobic and anaerobic capacities were determined in the laboratory tests, blood markers were also specified. Six training sessions improved swimming velocity in maximal 25-m swim test, as well as power outputs in Wingate test. However, no significant improvement was observed in the kinematics variables of eight 25-m repetitions. Aerobic capacities of the swimmers did not change essentially. Conclusion Two weeks of sprint interval training improved power abilities and speed in short distance swimming test. However, the short recovery intervals in training protocol may not positively affect the aerobic capacity.

Development of a high-resolution apparatus to monitor physiological state of a person undergoing extreme conditions

The present research has shown that ECG recordings and parameters of the body functional state are crucial for all kinds of the astronaut pre-flight preparations (centrifuge, thermal chamber, pressure chamber, pressure chamber with special equipment). It is, therefore, important to develop methods and tools for early detection of the preclinical forms of the functional state disorders in patients undergoing high-intensity loads of mixed character. The method based on the hardware-software compleх (HSC) with nanosensors of high resolution has been proposed to measure the electrophysiological characteristics and bioelectrical impedance of the body tissues directly exposed to loading. The hardware-software compleх is subjected to clinical trials in Tomsk Research Institute for Cardiology. The obtained results show that the use of nanosensors of high resolution in the HSC without standard filters allows elimination of the power-line interference in ECG recordings. Monitoring of the tissue bioimpedance parameters under test loads enables the detection of preclinical (latent) forms of various diseases. After clinical trials in Tomsk Institute for Cardiology the developed apparatus will be proposed for in-depth study of the cardiovascular system and the functional state of the body of astronauts and other persons exposed to extreme loads.