Anaerobic Threshold Intensity Research Articles

Comparison of selected performance-associated parameters after off-season and two-month training preparation in professional Czech ice hockey players

Background: In ice hockey, regular off-ice testing can serve as a controlling mechanism for a training program's effectiveness. Objective: The main aim of this study was to describe changes in selected morphological and physiological parameters, intended to be relevant for a complex ice hockey performance, after two months of pre-season training preparation following one month of an off-season period. Methods: The sample consisted of 22 adult male players aged 18-39 years from a top Czech ice hockey league team. Two laboratory testing procedures performed at the end of the off-season and after two months of the pre-season conditioning consisted of basic anthropometry and body composition measurements, countermovement jump (CMJ), and maximal incremental test focused on the assessment of various parameters, including maximal oxygen consumption (V̇O2max), maximal power output during the test (Pmax) or estimation of anaerobic threshold intensity (ANT). Results: After the pre-season, we found a significant decrease in body fat (13.7 vs. 11.4%, p < .001) and an increase in fat-free mass (74.2 vs. 76.6 kg, p < .001), V̇O2max (relative 48.8 vs. 52.6 ml.kg-1.min-1 p = .001; absolute 4.20 vs. 4.54 L.min-1, p < .001), Pmax (5.26 vs. 5.44 W.kg-1, p = .011), power output at ANT (4.07 vs. 4.35 W.kg-1, p < .001), and CMJ (44.9 vs. 47.1 cm, p = .002). Conclusions: Based on our results, two months of the pre-season training program led to a significant improvement in body composition and physical performance levels in professional Czech ice hockey players.

The comparison of endothelial function of moderate intensity interval exercise with continuous exercise in healthy men.

Background/aimExercise enhances endothelium-dependent vasodilation; however, it is unclear whether intermittent exercise has a different effect on vascular endothelial function compared to continuous exercise. This study aimed to compare vascular endothelial function following intermittent exercise including short rest intervals with continuous exercise, both at the anaerobic threshold level.Materials and methodsPeak oxygen consumption (VO2 peak) and anaerobic threshold were measured in physically active healthy young men (n = 12) by breath-by-breath analysis. After completion of intermittent exercise consisting of eight 1-min long intervals at the anaerobic threshold intensity with 75-s rest periods, total work was calculated. Equivalent work was done during continuous exercise. Immediately after the two exercise periods, venous blood lactate, endothelial nitric oxide synthase (eNOS), endothelin-1, N-terminal proANP (NTproANP), N-terminal proBNP (NTproBNP), and N-terminal proCNP (NTproCNP) levels were measured. Brachial artery flow-mediated dilatation (FMD) was measured before exercise and 30 min after exercise.ResultsMean VO2 peak level was 33.42 ± 5.9 ml/min/kg and anaerobic threshold level was 47.33 ± 5.85%. Lactate levels following continuous exercise were higher than levels following intermittent exercise (27.76 ± 7.43 mg/dl, 18.54 ± 4.87 mg/dl respectively; p˂0.05). Endothelin-1, eNOS, NTproANP, NTproBNP, and NTproCNP levels were similar after both modalities of exercise (p > 0.05). No significant difference was found in FMD response when comparing intermittent and continuous exercise (7.05 ± 15.11%, 2.49 ± 16.24% respectively; p > 0.05).ConclusionSince blood lactate levels are higher following continuous exercise, individuals who find difficulty exercising may prefer an intermittent form of exercise. However, both intermittent and continuous exercise at the anaerobic threshold level seem to not produce a significant acute change in endothelial function in healthy men.

Efficacy and Safety of Different Aerobic Exercise Intensities in Patients With Heart Failure With Reduced Ejection Fraction: Design of a Multicenter Randomized Controlled Trial (HF-EI Trial).

Background: Heart failure (HF) is one of the major causes of mortality worldwide, representing the terminal stage of several cardiovascular diseases. Exercise-based rehabilitation is a beneficial therapy for patients with chronic heart failure (CHF). However, there is a lack of specific guidance on clinical decision-making regarding optimal exercise intensity. It is necessary to optimize the clinical recommendations for HF exercises. We will evaluate the efficacy and safety of different aerobic exercise intensities in patients with heart failure with reduced ejection fraction (HFrEF): the HF-EI trial. This trial aims to assess the appropriate exercise intensity for patients with HFrEF.Methods: After a baseline assessment to determine the safety of exercise, 180 patients will be randomly assigned to supervised high-intensity exercise training (ET) group, supervised moderate intensity training (MIT) group, and control group at a ratio of 1:1:1. Patients randomly receiving high intensity training (HIT) undergo supervised ET (3 times/week, 30 min) for aerobic endurance at 70% peak oxygen consumption (peak VO2) intensity for 12 weeks. The MIT patients will perform supervised aerobic ET (3 times/week, 35–42 min) at the anaerobic threshold (AT) intensity for 12 weeks. The control group will continue to maintain their daily activities and will not receive ET. During the baseline and follow-up period, physical examination, laboratory tests, cardiology diagnostic tests, cardiopulmonary exercise tests (CPET), 6-min walk distance (6MWD), scale scores, exercise steps, medications, and clinical events will be monitored. Throughout the research, sport bracelets and patient diaries will be used to monitor and record overall physical activity, training courses, and compliance.Discussion: The HF-EI trial will evaluate the effects of different aerobic exercise intensities on peak VO2, quality of life (QoL), and clinical events among patients with HFrEF. The findings of this trial will provide a basis for formulating exercise prescriptions for patients with HFrEF.Clinical Trial Registration:http://www.chictr.org.cn/, identifier: ChiCTR2000036381.

Effects of exercise at the anaerobic threshold on respiratory quotient in young male subjects

Aim: Exercise has great influence on increasing metabolic system functions. The work load corresponded to anaerobic threshold provide optimal aerobic strain for metabolic activity in exercising muscle. In the present study we intended to evaluate body substrate oxidation ratio during constant load exercise test at the intensity of anaerobic threshold in healthy young male subjects. Material and Method: Total of 15 male performed an incremental ramp exercise test to estimate anaerobic threshold. Standard V-slope method used to estimate anaerobic threshold. Then each subject performed a constant load exercise test for a 30 min period with a work load corresponded to their anaerobic threshold. Respiratory quotient (RQ) used to evaluate substrate oxidations during exercise. Anova test used to evaluate significance of data obtained every 5 minutes of constant load exercise. Results: The subjects’ anaerobic threshold occurred at approximately 63% of their maximal exercise capacity. RQ varied markedly among the subjects but as a mean value, but it systematically decreased with increasing exercise time. Body mass index and exercise time has great importance on fat and carbohydrate oxidation ratio. Conclusion: Exercise intensity at the anaerobic threshold provides meaningfully fat oxidation and could be acceptable in subjects with high body fat mass.

Aerobic Training Modulates the Increase in Plasma Concentrations of Cytokines in response to a Session of Exercise.

Acute physical exercise can modulate immune function. For example, acute exercise is known to increase the circulating concentration of cytokines. Exercise is also known to modulate immune function chronically. It is not known whether exercise training can result in training of the immune system. Here, we investigated the effects of six weeks of aerobic training on cytokine responses induced by acute exercise until fatigue. Twelve healthy men performed a fatiguing exercise at the anaerobic threshold (AT) intensity. After the training period, the participants performed another bout of acute exercise at the same duration and intensity of the pretraining situation. The analysis was made at the beginning, end, and at 10, 30, and 60 minutes during the recovery period. Training at AT induced a gain of 11.2% of exercise capacity. Before training, a single bout of acute exercise induced a significant increase in plasma levels of cytokines, including IL-6, TNF-α, sTNFR1, IL-10, CXCL10, BDNF, leptin, resistin, and adiponectin. After six weeks of aerobic training, levels of IL-6, sTNFR1, BDNF, and leptin increased to a lesser extent after an acute bout exercise at the same absolute intensity as the pretraining period. Responses to the same relative exercise intensity were similar to those observed before exercise. These results show that aerobic training is associated with training of acute immune responses to acute exercise until fatigue.

Periodized versus non-periodized swimming training with equal total training load: Physiological, molecular and performance adaptations in Wistar rats.

This study investigated the effect of non-periodized training performed at 80, 100 and 120% of the anaerobic threshold intensity (AnT) and a linear periodized training model adapted for swimming rats on the gene expression of monocarboxylate transporters 1 and 4 (MCT1 and 4, in soleus and gastrocnemius muscles), protein contents, blood biomarkers, tissue glycogen, body mass, and aerobic and anaerobic capacities. Sixty Wistar rats were randomly divided into 6 groups (n = 10 per group): a baseline (BL; euthanized before training period), a control group (GC; not exercised during the training period), three groups exercised at intensities equivalent to 80, 100 and 120% of the AnT (G80, G100 and G120, respectively) at the equal workload and a linear periodized training group (GPE). Each training program lasted 12 weeks subdivided into three periods: basic mesocycle (6 weeks), specific mesocycle (5 weeks) and taper (1 week). Although G80, G100 and G120 groups were submitted to monotony workload (i.e. non-modulation at intensity or volume throughout the training program), rodents were evaluated during the same experimental timepoints as GPE to be able comparisons. Our main results showed that all training programs were capable to minimize the aerobic capacity decrease promoted by age, which were compared to control group. Rats trained in periodization model had reduced levels of lipid blood biomarkers and increased hepatic glycogen stores compared to all other trained groups. At the molecular level, only expressions of MCT1 in the muscle were modified by different training regimens, with MCT1 mRNA increasing in rats trained at lower intensities (G80), and MCT1 protein content showed higher values in non-periodized groups compared to pre-training and GPE. Here, training at different intensities but at same total workload promoted similar adaptations in rats. Nevertheless, our results suggested that periodized training seems to be optimize the physiological responses of rats.

The Comparison of 12 Weeks Continuous Training at Fatmax and Anaerobic Threshold Intensities and High Intensity Interval Training on Antioxidant Enzymes and Lipid Peroxidation Index in Pre-diabetic Patients

Background: Prediabetes state is associated with increased oxidative stress index and reduced of antioxidants. The aim of this study was to assess the effect of 12 weeks continuous training at Fatmax intensity and anaerobic threshold, and high-intensity interval training on antioxidant enzymes and lipid peroxidation index in pre-diabetic patients. Methods: Thirty-two pre-diabetic patients (age: 38.7 ± 4.0 yrs; body mass index: 26.9 ± 1.4 kg/m2; percent body fat (%): 26.1 ± 2.5; VO2Peak: 2.49 ± 0.22 l/min) were divided into 4 groups (n=8) control (CON), high-intensity interval training (HIT), continuous training at Fatmax intensity (FAT) and continuous training at anaerobic threshold (IAT) groups. Subjects of the HIT, FAT, and IAT groups run out their specific exercise training for 12 weeks. Blood Malondialdehyde (MDA), Superoxide Dismutase (SOD) and Catalase (CAT) were determined in the lab. The student’s t-test and ANCOVA were used to analyze the data. Results: The effect of exercise training on glucose concentration in FAT, IAT and HIT groups was 12%, 10% and 17%, respectively; the difference was significant in the training groups in comparison to CON group (p≤0.05). SOD and CAT in the training groups were significantly (p<0.05) increased when compared to the pre-training values. Also, FAT, IAT and HIT resulted in significant (p<0.05) changes in MDA compared to baseline. Conclusion: The training protocols had similar effects on the insulin resistance index in prediabetic patients. Also, continuous endurance training with low- to moderate-intensity and high intensity interval training are effective protocols for the modulation of antioxidant enzymes and lipid peroxidation index.

Açai pulp supplementation as a nutritional strategy to prevent oxidative damage, improve oxidative status, and modulate blood lactate of male cyclists.

Açai pulp is a source of phytochemicals and has been associated with antioxidant, anti-inflammatory, and antigenotoxic effects. This study aimed to assess the effects of açai pulp consumption on oxidative, inflammatory, and aerobic capacity markers of cyclist athletes. A crossover, randomized, placebo-controlled, single-blind study was developed with ten male cyclists (33.5 ± 4.7years old, body mass index of 23.9 ± 1.38kg/m2, and training load around 1875 ± 238 AU/week). The athletes consumed 400g/day of pasteurized açai pulp (AP) or placebo (PL) for 15days, with a 30-day wash-out period between trials. Lipid peroxidation, serum antioxidant capacity, DNA damage in peripheral blood (Comet assay), IL-6 and TNF-alpha, blood lactate concentration during effort, anaerobic threshold intensity (ATi), maximum workload reached (Wmax), rating of perceived exertion threshold (RPET), and heart rate threshold (HRT) were evaluated before and after each intervention. Data were analyzed using a linear regression model with mixed effects (p ≤ 0.05). Increased serum antioxidant capacity (p = 0.006) and decreased lipid peroxidation (p = 0.01) were observed in subjects after intervention with AP. Blood lactate levels during effort significantly decreased (by 29%, p = 0.025) and ATi increased (p = 0.006) after AP. No significant effect on DNA damage was attributed to AP consumption. We found notable effects of AP intervention on antioxidant status in athletes. Both the reduction in blood lactate concentration and increase in ATi during the effort suggest an overall improvement in the aerobic capacity of the cyclists, confirming that AP consumption may influence variables associated with performance in endurance athletes.

Analysis of the ergogenic effect of asynchronous music on physiological, psychophysiological and performance parameters obtained in an incremental runing test

Ten healthy male individuals were randomly evaluated in two exercise sessions (with or without music during the tests). They were submited to an incremental running test (3-min stages; initial intensity equal to 7 km.h-1 and 1 km.h-1 increments; treadmill inclination equal to 1%). The music´s motivation were adressed by the Brunel Rating Music Inventory- 2, considering the most motivation on top of the playlist, and then yours subsequents. Anaerobic threshold intensity (iAnT), blood lactate concentration ([Lac]iAnT) and heart rate (HRiAnT) at anaerobic threshold intensity were considered as physiological parameters. Psychophysiological scales such as Perceived Exertion (PSEBorg), Perceived Effort (PSEFoster) and Estimation of Time Limit (ETL) were used for psychophysiological analyses. Time to exhaustion (T.T) was considered as performance parameter. No differences were found between iAnT (p=0.248), [Lac]iAnT (p=0.786), HRiAnT (p=1.000) an T.T (p=0.055). However, 70% of the sample presented better performance with asynchronous music was inserted (p=0.003). Significant differences were visualized for PSEBorg (AM= ;WM= ;0,042) and ETL (AM= ;WM= ;p=0.015). In sumary, for 70% of the evaluated sample asynchronous music exerted ergogenic effect on the physical performance in an incremental running protocol attenuating the psychophysiological responses without changing physiological parameters.

Changes in Splenic Volume After the Treadmill Exercise at Specific Workloads in Elite Long-Distance Runners and Recreational Runners.

Introduction:Spleen acts as blood reservoir both in animals and human beings. Spleen contracts during the exercise and so augment the systemic circulation and helps body to maintain longer on high intensity exercise. Reviewing all available literature, the human spleen shows a decrease in volume, in range from 8% to 56%, depending on the work intensity.Aim:To evaluate the percentage of the decrease in splenic volume after the treadmill exercise at specific workloads: aerobic threshold intensity, anaerobic threshold intensity, submaximal intensity and maximal intensity.Methods:This prospective study with repeated measurements included 16 healthy subjects, divided in two groups. First group consisted of 8 elite long-distance runners and second group of 8 recreational runners. First testing consisted of treadmill ergospirometry test. This data was crucial for the second testing where subjects were exercising on treadmill at specific workloads. Four specific workloads were determined: treadmill exercise at aerobic threshold intensity (1st workload), anaerobic threshold intensity (2nd workload), submaximal intensity (3rd workload) and maximal intensity (4th workload). Workloads were controlled by the speed of treadmill, for each subject individually regarding the ergospirometry test. Ultrasound measurement of spleen was done before and after each workload.Results:Elite long-distance runners showed greater spleen contraction than recreational runners after four workloads. Spleen contraction was the biggest after the 3rd workload in elite long-distance runners. Smallest contraction was in group of recreational runners after the 1st workload. Statistically significant difference was not found between the groups, regarding the splenic volume after exercise at four specific workloads (p>0.05).Conclusion:Elite long-distance runners had greater decrease in splenic volume than recreational runners, after exercise at four specific workloads, without significant difference. Greatest decrease happened in elite long-distance runners, after exercise at submaximal intensity - 49% decrease in splenic volume.

Influence of Cooling Down Exercise on Heart Rate Variability after Steady Load Exercise at the Anaerobic Threshold Intensity

Influence of Cooling Down Exercise on Heart Rate Variability after Steady Load Exercise at the Anaerobic Threshold Intensity

Evaluation of Endurance Physiological Characteristics in Road Cyclists

The purpose of our investigation was to determine the most informative physiological characteristics to monitor training effect in highly qualified road cyclists.Fourteen Latvian Olympic Team road cyclists with training experience from seven to nine years participated in theinvestigation voluntarily (their average age was 19.3 ± 1.1 years, height — 183.6 ± 5.4 cm, body mass — 73.4 ± 3.8 kg). The aerobic performance tests were carried out in the Latvian Olympic Team Laboratory at the initial and middle phase of their preparation period of training. The initial load of 27 W was increased every two minutes step by step by 12 W. The cardiopulmonary diagnostic equipment was used to register the electrocardiograms and respiratory characteristics. The lactic acid concentration in the capillary blood was tested. The maximal oxygen uptake (4.62 ± 0.40 l / min and 63.2 ± 4.8 ml / kg·min) and power output (376 ± 36 W and 5.13 ± 0.44 W / kg) in the cyclists were significantly lower in comparison with the data received by other authors. At the initial or middle phase of the preparation period of training these characteristics did not reach their maximal values. The oxygen uptake (3.85 ± 0.30 l / min and 52.6 ± 3.7 ml / kg·min) and power output (296 ± 28 R and 4.04 ± 0.33 W / kg) at the anaerobic threshold intensity load were in a good agreement with the data of other investigators. These characteristics depend on the central and peripheral mechanisms of aerobic capacity in the cyclists, and are useful in the estimation and monitoring of the endurance performance. The data reported by different authors of aerobic threshold physiological characteristics in highly qualified cyclists were contradicting, which can be explained by different test protocols and differences in the rate of lactate accumulation in the capillary blood, especially in the initial phase of the test. Our investigations showed that the oxygen uptake was 2.57 ± 0.35 l / min and 35.0 ± 4.7 ml / kg·min, and power output was 182 ± 36 W and 2.48 ± 0.47 W / kg. The mechanical efficiency (21.9 ± 1.2%) and economy of cycling movements (4.602 ± 0.268 kJ / l) in the cyclists reached their maximal values at the anaerobic threshold, which is the intensity of load specific to road cycling. It proves high homogeneity of the mechanical efficiency and economy of movements among the cyclists, and lack of the significant correlation between these characteristics and the power output on the bicycle ergometer (r = 0.19 and 0.20, respectively; p &gt; 0.05).Keywords: cycling, aerobic capacity, work mechanical efficiency, aerobic and anaerobic thresholds.

Shorter Ground Contact Time and Better Running Economy: Evidence From Female Kenyan Runners.

Mooses, M, Haile, DW, Ojiambo, R, Sang, M, Mooses, K, Lane, AR, and Hackney, AC. Shorter ground contact time and better running economy: evidence from female Kenyan runners. J Strength Cond Res 35(2): 481-486, 2021-Previously, it has been concluded that the improvement in running economy (RE) might be considered as a key to the continued improvement in performance when no further increase in V̇o2max is observed. To date, RE has been extensively studied among male East African distance runners. By contrast, there is a paucity of data on the RE of female East African runners. A total of 10 female Kenyan runners performed 3 × 1,600-m steady-state run trials on a flat outdoor clay track (400-m lap) at the intensities that corresponded to their everyday training intensities for easy, moderate, and fast running. Running economy together with gait characteristics was determined. Subjects showed moderate to very good RE at the first (202 ± 26 ml·kg-1·km-1) and second (188 ± 12 ml·kg-1·km-1) run trials, respectively. Correlation analysis revealed significant relationship between ground contact time (GCT) and RE at the second run (r = 0.782; p = 0.022), which represented the intensity of anaerobic threshold. This study is the first to report the RE and gait characteristics of East African female athletes measured under everyday training settings. We provided the evidence that GCT is associated with the superior RE of the female Kenyan runners.

Increased Perceived Effort during Low-Intensity Exercise Linked to Type 2 Diabetes

Exercise is a cornerstone of type 2 diabetes (T2D) treatment, but most people with T2D are sedentary. We identified a novel behavioral barrier to exercise in women with T2D compared to nondiabetic women — greater effort during low intensity exercise. We hypothesized that the presence of T2D would confer greater effort for adults across a range of exercise intensities, even when controlling for fitness. As T2D decreases fitness more in women than men, we also hypothesized sex would modify this association. We analyzed secondary data from past sedentary, overweight research participants with and without T2D who were free of cardiopulmonary comorbidities. During graded exercise tests to assess fitness (VO2peak), we repeatedly measured objective effort (heart rate (HR)) and subjective effort (Borg Rating of Perceived Exertion (RPE)). We plotted the rise of RPE and HR, respectively, against increases in relative work rate (%VO2peak: VO2 at work rate divided by VO2peak) at lower intensities below anaerobic threshold (AT) and higher intensities above AT. Adults with T2D (n=57) had similar age and adiposity as those without T2D (n=55), but had lower VO2peak: 20.7± 4.5 vs. 24.5 ± 6.6 ml/kg/min (p&amp;lt;0.05). Below AT, people with T2D had a steeper rise in RPE for each unit increase in %VO2peak than those without T2D (p=0.0029), and this finding was more pronounced in men than women (p=0.004). T2D status did not influence the association of %VO2peak and RPE above AT, or the association of HR and %VO2peak either below or above AT. People with T2D have significantly greater RPE during lower intensity exercise below AT as compared to people without T2D. This finding was not explained by fitness differences and, counter to our hypothesis, was more significant in men. We found no group differences in RPE at higher intensity exercise where physiological inputs tend to dominate behavioral predictors of effort. Future work should further characterize sex-specific mechanisms of exercise effort for people with T2D. Disclosure A.G. Huebschmann: Research Support; Self; Merck &amp; Co., Inc.. M. Wahl: None. R.L. Scalzo: None. D. Rafferty: None. J.G. Regensteiner: None.

Level of performance and stability of cardiopulmonary variables in the intensity of the ventilatory anaerobic threshold

Abstract AIM The aim of this study was to describe the behavior of different cardiopulmonary variables in exercise session with constant running speed, corresponding to the intensity of ventilatory anaerobic threshold and identifying the steady state in a different level of performance. METHODS A cross-sectional study with nine elite athletes (31 ± 5.7 years, 1.7 ± 0.05 meters and 2max 68.6 ± 3.2 mL·kg-1·min-1) and nine non-athletes (32 ± 10 years, 1.8 ± 0.1 meters and 2max 47.2± 4.4 mL·kg-1·min-1). Two visits to the laboratory have been conducted. Firstly, cardiopulmonary exercise testing until voluntary exhaustion took place to identify ventilatory thresholds and maximum oxygen consumption (2max) and secondly, there was a running session for 1 hour in ventilatory anaerobic threshold speed, with continuous measurement of exhaled gases. A range of 5% (∆5%) for VO2 and PetCO2 was used; 5.5% (∆5.5%) for VE and 3% (∆3%) for respiratory exchange ratio (RER) and one-way ANOVA with statistical significance of p ≤ 0.05 to identify the steady state of results. OOO RESULTS A session with constant speed related to ventilatory anaerobic threshold intensity showed similarity in the steady state of ventilatory variables except for RER in the NA group (p ≤ 0.05). CONCLUSION It was possible to identify the steady state from ventilatory variables related to ventilatory anaerobic threshold intensity that occurred independently of the physical performance level.

The Effect of Visual Speed Swimming Control in Swimmers’ Threshold Training

Controlling swimming speed is an important factor as far as accomplishing swimming training tasks is concerned. The aim of this study was to determine the importance of visual information about control of swimming speed in threshold training for swimmers. Six swimmers took part in this experiment. The study consisted of two exercise tests in which the participants swam 10 x 100m. Individually designated task time corresponded to intensity of 95-100% of anaerobic threshold (AnT) intensity. AnT was determined in a progressive test prior to the experiment. In the first exercise test participants did not receive information regarding their swimming speed. In the second test visual information regarding their swimming speed was transmitted in real time using the Swimming Pace Control System device. The effect of visual control of swimming speed in threshold training for swimmers was determined by measuring the time needed to complete the test distances, heart rate and lactate concentration. Visual information used in swimming speed control in real-time statistically significantly reduces the differences between the assumed and actual time needed to complete the test distance (p=0.057). Visual control of swimming speed resulted in an appropriate level achievement of intensity for threshold training, which was measured by swimming time (inaccuracy 6.97±1.38 s), heart rate ( 162.7±15.9 beat/min), and lactate concentration ( 4.70±1.78mmol/l). Comparing the increase in lactate concentration and exercise test with visual information, statistically significant differences are not observed (p=0.710; p=0.947). However, among 33.33% of the subjects, lactate concentration after training without visual information did not meet the standards (4 to 5 mmol/l) of threshold training (8.85 mmol/l and 14.57 mmol/l). Additionally, value of standard deviations of lactate concentration after threshold training with visual information amounted to 37.87% mean of lactate concentration, and in the condition without information 84.00% mean of lactate concentration. The results indicate the need to use concurrent visual information provided in real-time allowing you to control the swimming speed in swimming training.

Exercise Prescription Using the Borg Rating of Perceived Exertion to Improve Fitness.

The present study aimed to compare two fitness-training methodologies, instability circuit resistance training (ICRT) versus traditional circuit resistance training (TCRT), applying an experimental model of exercise prescription controlling and modulating exercise load using the Borg rating of perceived exertion. Forty-four healthy young adults age (21.6±2.3 years) were randomly assigned to three groups: TCRT (n=14), ICRT (n=14) and a control group (n=16). Strength and cardiorespiratory tests were chosen to evaluate cardiorespiratory and muscular fitness before and after the training program. In cardiorespiratory data, a significant difference was observed for the time effect in VO2max, peak heart rate, peak velocity, and heart rate at anaerobic threshold intensity (p<0.05) in the experimental groups. In strength variables, a significant Group x Time interaction effect was detected in 1RM, in mean propulsive power, and in peak power (p≤0.01) in the back squat exercise. In the bench press exercise, a significant time effect was detected in 1RM, in mean propulsive power, and in peak power, and a Group x Time interaction in peak power (all p<0.05). We can conclude that applying an experimental model of exercise prescription using RPE improved cardiorespiratory and muscular fitness in healthy young adults in both experimental groups.

Moderate exercise based on artificial gravity preserves orthostatic tolerance and exercise capacity during short-term head-down bed rest.

Numerous countermeasures have been proposed to minimize microgravity-induced physical deconditioning, but their benefits are limited. The present study aimed to investigate whether personalized aerobic exercise based on artificial gravity (AG) mitigates multisystem physical deconditioning. Fourteen men were assigned to the control group (n=6) and the countermeasure group (CM, n=8). Subjects in the CM group were exposed to AG (2 Gz at foot level) for 30 min twice daily, during which time cycling exercise of 80-95 % anaerobic threshold (AT) intensity was undertaken. Orthostatic tolerance (OT), exercise tests, and blood assays were determined before and after 4 days head-down bed rest (HDBR). Cardiac systolic function was measured every day. After HDBR, OT decreased to 50.9 % and 77.5 % of pre-HDBR values in control and CM groups, respectively. Exercise endurance, maximal oxygen consumption, and AT decreased to 96.5 %, 91.5 % and 91.8 % of pre-HDBR values, respectively, in the control group. Nevertheless, there were slight changes in the CM group. HDBR increased heart rate, sympathetic activity, and the pre-ejection period, but decreased plasma volume, parasympathetic activity and left-ventricular ejection time in the control group, whereas these effects were eliminated in the CM group. Aldosterone had no change in the control group but increased significantly in the CM group. Our study shows that 80-95 % AT aerobic exercise based on 2 Gz of AG preserves OT and exercise endurance, and affects body fluid regulation during short-term HDBR. The underlying mechanisms might involve maintained cardiac systolic function, preserved plasma volume, and improved sympathetic responses to orthostatic stress.

Effects of Beetroot Juice Supplementation on Cardiorespiratory Endurance in Athletes. A Systematic Review.

Athletes use nutritional supplementation to enhance the effects of training and achieve improvements in their athletic performance. Beetroot juice increases levels of nitric oxide (NO), which serves multiple functions related to increased blood flow, gas exchange, mitochondrial biogenesis and efficiency, and strengthening of muscle contraction. These biomarker improvements indicate that supplementation with beetroot juice could have ergogenic effects on cardiorespiratory endurance that would benefit athletic performance. The aim of this literature review was to determine the effects of beetroot juice supplementation and the combination of beetroot juice with other supplements on cardiorespiratory endurance in athletes. A keyword search of DialNet, MedLine, PubMed, Scopus and Web of Science databases covered publications from 2010 to 2016. After excluding reviews/meta-analyses, animal studies, inaccessible full-text, and studies that did not supplement with beetroot juice and adequately assess cardiorespiratory endurance, 23 articles were selected for analysis. The available results suggest that supplementation with beetroot juice can improve cardiorespiratory endurance in athletes by increasing efficiency, which improves performance at various distances, increases time to exhaustion at submaximal intensities, and may improve the cardiorespiratory performance at anaerobic threshold intensities and maximum oxygen uptake (VO2max). Although the literature shows contradictory data, the findings of other studies lead us to hypothesize that supplementing with beetroot juice could mitigate the ergolytic effects of hypoxia on cardiorespiratory endurance in athletes. It cannot be stated that the combination of beetroot juice with other supplements has a positive or negative effect on cardiorespiratory endurance, but it is possible that the effects of supplementation with beetroot juice can be undermined by interaction with other supplements such as caffeine.

The effects of two different swimming training periodization on physiological parameters at various exercise intensities

This study analysed the effects of two different periodization strategies on physiological parameters at various exercise intensities in competitive swimmers. Seventeen athletes of both sexes were divided to two groups, the traditional periodization (TPG, n = 7) and the reverse periodization group (RPG, n = 10). Each group followed a 10-week training period based on the two different periodization strategies. Before and after training, swimming velocity (SV), energy expenditure (EE), energy cost (EC) and percentage of aerobic (%Aer) and anaerobic (%An) energy contribution to the swimming intensities corresponding to the aerobic threshold (AerT), the anaerobic threshold (AnT) and the velocity at maximal oxygen uptake (vVO2max) were measured. Both groups increased the %An at the AerT and AnT intensity (P ≤ .05). In contrast, at the AnT intensity, EE and EC were only increased in TPG. Complementary, %Aer, %An, EE and EC at vVO2max did not alter in both groups (P > .05); no changes were observed in SV in TPG and RPG at all three intensities. These results indicate that both periodization schemes confer almost analogous adaptations in specific physiological parameters in competitive swimmers. However, given the large difference in the total training volume between the two groups, it is suggested that the implementation of the reverse periodization model is an effective and time-efficient strategy to improve performance mainly for swimming events where the AnT is an important performance indicator.