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Purpose: Molecular hydrogen has been shown to possess antioxidant, antiinflammatory, ergogenic, and recovery-enhancing effects. This study aimed to assess the effect of molecular hydrogen administration on muscle performance, damage, and perception of soreness up to 24 h of recovery after two strenuous training sessions performed on the same day in elite fin swimmers. Methods: Eight females (mean ± SD; age 21.5 ± 5.0 years, maximal oxygen consumption 45.0 ± 2.5mL.kg-1.min-1) and four males (age 18.9 ± 1.3years, maximal oxygen consumption 52.2 ± 1.7mL.kg-1.min-1) performed 12 × 50m sprints in the morning session and a 400m competitive performance in the afternoon session. Participants consumed hydrogen-rich water (HRW) or placebo 3 days before the sessions (1,260mL/day) and 2,520mL on the experimental day. Muscle performance (countermovement jump), muscle damage (creatine kinase), and muscle soreness (100mm visual analogue scale) were measured during the experimental day and at 12 and 24 h after the afternoon session. Results: HRW compared to placebo reduced blood activity of creatine kinase (156 ± 63 vs. 190 ± 64 U.L-1, p = 0.043), muscle soreness perception (34 ± 12 vs. 42 ± 12 mm, p = 0.045), and improved countermovement jump height (30.7 ± 5.5 cm vs. 29.8 ± 5.8 cm, p = 0.014) at 12 h after the afternoon session. Conclusion: Four days of HRW supplementation is a promising hydration strategy for promoting muscle recovery after two strenuous training sessions performed on the same day in elite fin swimmers. [ABSTRACT FROM AUTHOR]

Purpose: Hydrogen-rich water (HRW) has been shown to have an antifatigue effect. This study assessed up-hill running performance, as well as physiological and perceptual responses after supplementation with 1680 mL HRW between 24 h and 40 min before running, in athletes of heterogeneous running ability. Methods: Sixteen males (mean [SD] age 31.6 [8.6] y, VO2max 57.2 [8.9] mL·kg−1·min−1, body fat 13.4% [4.4%]) participated in this study. Using a randomized, double-blind, placebo-controlled crossover design, participants consumed either HRW or placebo prior to performing two 4.2-km up-hill races separated by a week. Race time (RT), average race heart rate, and immediately postrace rating of perceived exertion were assessed. Results: After analysis of data for all runners, HRW effect was unclear (−10 to 7 s, 90% confidence interval) for RT, likely trivial for heart rate (−2 to 3 beats·min−1), and likely trivial for postrace rating of perceived exertion (−0.1 to 1.0). A possible negative correlation was found between RT differences and average RT (r = −.79 to −.15). HRW for the 4 slowest runners (RT = 1490 [91] s) likely improved the RT (−36 to −3 s), whereas for the 4 fastest runners (RT = 1069 [53] s) the performance effect of HRW was unclear (−10 to 26 s). Conclusions: HRW intake had an unclear antifatigue effect on performance in terms of mean group values. However, it appears that the magnitude of the antifatigue effect of HRW on performance depends on individual running ability. [ABSTRACT FROM AUTHOR]

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 (VO2max), 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), VO2max (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. [ABSTRACT FROM AUTHOR]

Purpose: This study investigated the effects of acute, pre-exercise, hydrogen rich water (HRW) ingestion on running time to exhaustion at maximal aerobic speed in trained track and field runners. Methods: Twenty-four, male runners aged 17.5 ± 1.8 years, with body mass index = 21.0 ± 1.3 kg⋅m-2, and maximal oxygen uptake = 55.0 ± 4.6 ml⋅kg-1⋅min-1 (mean ± standard deviation) participated in this randomized, double-blind, placebo-controlled crossover study. All runners ingested 1260 ml of HRW which was divided into four doses and taken at 120 min (420 ml), 60 min (420 ml), 30 min (210 ml), and 10 min (210 ml) prior to exercise. The running protocol consisted of three phases: warm-up performed at 10 km⋅h-1 for 3 min, followed by a transition phase performed at an individually determined speed (10 km⋅h-1 + maximal aerobic speed)/2 for 1 min, and finally the third phase performed at individual maximal aerobic speed until exhaustion. Time to exhaustion, cardiorespiratory variables, and post-exercise blood lactate concentration were measured. Results: When running to exhaustion at maximal aerobic speed, compared with placebo, HRW had no significant effects on the following variables: time to exhaustion (217 ± 49 and 227 ± 53 s, p = 0.20), post-exercise blood lactate concentration (9.9 ± 2.2 and 10.1 ± 2.0 mmol⋅L-1, p = 0.42), maximal heart rate (186 ± 9 and 186 ± 9 beats⋅min-1, p = 0.80), and oxygen uptake (53.1 ± 4.5 and 52.2 ± 4.7 ml⋅kg-1⋅min-1, p = 0.33). No variable assessed as a candidate moderator was significantly correlated with time to exhaustion (Spearman's correlation coefficients ranged from −0.28 to 0.30, all p ≥ 0.16). Conclusions: Pre-exercise administration of 1260 ml of HRW showed no ergogenic effect on running performance to exhaustion at maximal aerobic speed in trained track and field runners. [ABSTRACT FROM AUTHOR]

Botek, M, Krejčí, J, McKune, A, Valenta, M, and Sládečková, B. Hydrogen rich water consumption positively affects muscle performance, lactate response, and alleviates delayed onset of muscle soreness after resistance training. J Strength Cond Res 36(10): 2792–2799, 2022—Positive outcomes of hydrogen rich water (HRW) supplementation on endurance performance have been shown, but the effects of HRW in resistance training are unclear. The aim of this study was to assess the effects of 1,260 ml of HRW intake on physiological, perceptual, and performance responses to a resistance training and after 24 hours of recovery. This randomized, double-blinded placebo-controlled cross-over study included 12 men aged 23.8 ± 1.9 years. Subjects performed a half squat, knee flexion, and extension exercises with the load set at 70% of 1 repetition maximum for 3 sets (10 reps/set). Lunges were performed with a load of 30% of body mass for 3 sets (20 reps/set). Time of each set, lactate, and ratings of perceived exertion were assessed mid-way through exercise and immediately after the exercise. Creatine kinase, muscle soreness visual analog scale ratings, countermovement jump, and heart rate variability were evaluated before the training and at 30 minutes, 6, and 24 hours of recovery. Lunges were performed faster with HRW compared with placebo (p < 0.001). Hydrogen rich water reduced lactate at mid-way and immediately after the exercise (HRW: 5.3 ± 2.1 and 5.1 ± 2.2, placebo: 6.5 ± 1.8 and 6.3 ± 2.2 mmol·L−1, p ≤ 0.008). Visual analog scale ratings were significantly lower with HRW (26 ± 11 vs. 41 ± 20 mm, p = 0.002) after 24 hours of recovery. In conclusion, an acute intermittent HRW hydration improved muscle function, reduced the lactate response, and alleviated delayed onset of muscle soreness. [ABSTRACT FROM AUTHOR]

Background: Vibroacoustic therapy (VAT) uses low-frequency sound, often combined with listening to music, for therapeutic purposes. However, the impact of low-frequency vibration (LFV) on physiological functions and subjective perception is relatively unknown. Methods: We conducted a randomized cross-over study with the aim of comparing the effect of constant LFV of 40 Hz, its amplitude modulation, and the placebo condition on heart rate variability (HRV), stress perception (measured by visual analogue scales for stress) and mood (measured by UWIST Mood Adjective Check List). Results: Research experiments with various interventions (constant LFV with sound of nature (river in forest), amplitude modulation of the same LFV with sounds of nature and sounds of nature without LFV) were realised involving 24 participants. It was found there was an effect on HRV, stress perception and mood after the interventions. However, there were only seldomly experienced, and mostly nonsignificant, differences between the intervention conditions, so the effects may be attributed to factors other than LFV. Conclusions: Large scale experimental studies are needed to verify the preliminary findings and to explore various coinciding factors that may have influenced the results of this study, e.g., type of autonomic nervous system. We propose that the effect of LFV exposure may differ when combined with listening to music, and this hypothesis should be investigated in future studies. [ABSTRACT FROM AUTHOR]

Our results also show that fluid intake perception negatively correlated with USG ( I r i SB S sb =0.46, I p i <0.001), and the difference in beverage consumption between EU and DE players was in line with the difference in their evaluation of beverage intake. Therefore, the objective of the present study was to determine the hydration status of Czech male soccer league players, and to compare the reported beverage intake, perceived consumption of the beverage and thirst sensation between euhydrated (EU) and dehydrated (DE) athletes. Fluid intake and thirst perception Athletes completed a self-report Fluid intake and thirst perception questionnaire consisting of 17-items ([25]). Keywords: dehydration; athletes; urine specific gravity; self-assessment questionnaire EN dehydration athletes urine specific gravity self-assessment questionnaire 101 110 10 04/29/22 20220415 NES 220415 Introduction It is well documented that dehydration impairs an athlete's physical performance, and adequate hydration is important to optimize physiological functions relevant to sports performance. [Extracted from the article]

Background: Hydrogen-rich water (HRW) has been shown to have a stimulating effect on the human body. Objective: The aim of the study was to assess the influence of acute HRW intake on autonomic cardiac regulation during 50 min of rest sitting. Methods: Fourteen healthy females (age 21.7 ± 1.2 years, body mass 67.8 ± 8.7 kg, height 167 ± 5.5 cm) took part in this double-blind, randomized, placebo-controlled trial with crossover design. Heart rate variability (HRV) was monitored in the sitting position after administration of 1260 ml of HRW or placebo. Time domain indexes of HRV as the square root of the mean of the squares of differences between adjacent RR intervals (RMSSD), the standard deviation of all RR intervals (SDNN) and the ratio of SDNN/RMSSD as an index of sympatho-vagal balance were used to assess autonomic cardiac response. The values were transformed using natural logarithm (Ln). Results: After administration of HRW, we found significantly increased ratio Ln SDNN/RMSSD when comparing it to placebo in 25 min (HRW: 0.40 ± 0.30, placebo: 0.26 ± 0.25, p = .049) and 35 min (HRW: 0.44 ± 0.30, placebo: 0.28 ± 0.28, p = .029) of rest sitting. Ln SDNN was significantly increased after HRW administration when compared to placebo in 45 min (HRW: 4.41 ± 0.42 ms, placebo: 4.28 ± 0.31 ms, p = .049) of rest sitting. Conclusions: Acute HRW ingestion induced a relative increase in sympathetic activity between 25 and 35 min post-ingestion, whereas vagal activity was not affected. [ABSTRACT FROM AUTHOR]

The potential anti-fatigue and performance benefits of hydrogen rich water (HRW) have resulted in increased research interest over the past 5 years. The aim of this study was to assess physiological and perceptual responses to an incremental exercise protocol after administration of 600 ml HRW within 30 min before exercise. This randomized, double blinded placebo-controlled cross over study included twelve healthy males aged 27.1±4.9 years. The exercise protocol consisted of a 10 min warm-up at 1.0 W.kg−1 , followed by 8 min at 2.0, 3.0, and 4.0 W.kg−1 , respectively. Cardio-respiratory variables, lactate and ratings of perceived exertion (RPE) were assessed in the last minute of each step. A significantly lower blood lactate was found with HRW (4.0±1.6 and 8.9±2.2 mmol.l−1) compared to Placebo (5.1±1.9 and 10.6±3.0 mmol.l−1) at 3.0, and 4.0 W.kg−1 , respectively. Ventilatory equivalent for oxygen and RPE exhibited significantly lower values with HRW (32.3±7.2, and 17.8±1.2 points, respectively) compared to Placebo (35.0±8.4, and 18.5±0.8 points, respectively) at 4 W.kg−1. To conclude, acute pre-exercise supplementation with HRW reduced blood lactate at higher exercise intensities, improved exercise-induced perception of effort, and ventilatory efficiency. [ABSTRACT FROM AUTHOR]

Background: Although there is a well documented negative effect of dehydration on exercise performance, athletes commonly start their exercise inadequately hydrated. This fact suggests that athletes do not adequately replenish their fluids and we can also speculate that they are unable to properly estimate their beverage intake. Objective: To evaluate the hydration status, the beverage intake, and differences between perceived adequate fluid intake and laboratory indicator of hydration status in elite deaf athletes. Methods: It was a cross-sectional study. The research group consisted of 62 male athletes organized in the Czech Deaf Sports Federation at the age of 25.8 ± 8.3 years. Urine specific gravity (USG) was an indicator of hydration status. Beverage consumption and its subjective evaluation were questioned. Results: The prevalence of inadequate hydration was 54%, athletes reported common beverage intake 2.2 ± 0.9 L, plus 1.0 ± 0.5 L in relation to their practice. A negative correlation was revealed between beverages daily intake and USG (r = -.51, p < .001). Fifteen (24%) athletes assessed their beverage consumption as very good, 43 (69%) as good, and only 4 (6%) as poor. There was no significant (p = .950, η² = .002) association between perceived beverage consumption and USG. Conclusions: The majority of athletes was dehydrated based on their first morning urine sample. Athletes failed to subjectively evaluate their beverage consumption and perceived it as better than what the objective laboratory indicator (USG) showed. [ABSTRACT FROM AUTHOR]

Background: SAFT90 is a specific multidirectional fatigue protocol that imitates the internal and external load of soccer match-play. Objective: The aim of the study was to evaluate the impact of SAFT90 on lactate production, heart rate (HR) and rate of subjective perceived exertion (RPE) expressed by Borg scale (6-20). Methods: Fourteen male elite junior soccer players (age 15.9 ± 0.2 years, stature 180.8 ± 5.5 cm, body mass 69.8 ± 5.8 kg, body fat 8.1 ± 3.2%, VO2max 57.6 ± 4.7 ml⋅kg-1⋅min-1, maximum heart rate 192.8 ± 4.6 beats⋅min-1) participated in this study. Lactate concentration, HR and RPE were monitored during specific fatigue exercise protocol SAFT90. Results: Results of HR showed mean values of153 ± 15 beats⋅min-1, mean blood lactate concentration was 1.9 ± 0.5 mmol⋅L-1. A mean value of RPE was 11.0 ± 1.4 that corresponds to "fairly light" exercise. No significant change was found between consecutive SAFT90 stages for HR and lactate concentration. For Borg scale, there were significant increases between stages 20 min and 45 min and between stages 70 min and 90 min. Change between stages 45 and 70 min was not significant. Conclusions: In respect to study results, we suggest that specific fatigue protocol SAFT90 applied in U16 soccer players appears to be insufficient in terms of exercise intensity to achieve comparable lactate concentration, HR and RPE values with a soccer match. [ABSTRACT FROM AUTHOR]

Poor neuromuscular control and fatigue have been proposed as a risk factor for non-contact injuries especially around peak height velocity (PHV). This study explored the effects of competitive soccer match-play on neuromuscular performance and muscle damage in male youth soccer players. 24 youth players aged 13-16y were split into a PHV group (−0.5 to 0.5y) and post PHV group (1.0–2.5y) based on maturity off-set. Leg stiffness, reactive strength index (RSI), muscle activation, creatine kinase (CK), and muscle soreness were determined pre and post a competitive soccer match. Paired t-tests were used to explore differences pre and post competitive match play and independent sample t-tests for between groups differences for all outcome measures. There was no significant fatigue-related change in absolute and relative leg stiffness or muscle activation in both groups, except for the gastrocnemius in the post PHV group. RSI, CK and perceived muscle soreness were significantly different after soccer match-play in both groups with small to large effects observed (ES:0.41–2.82). There were no significant differences between the groups pre match-play except for absolute and relative leg stiffness (P < 0.001; ES = 1.16 and 0.63 respectively). No significant differences were observed in the fatigue related responses to competitive match play between groups except for perceived muscle soreness. The influence of competitive match-play on neuromuscular function and muscle damage is similar in male youth around the time of PHV and those post-PHV indicating that other factors must contribute to the heightened injury risk around PHV. [ABSTRACT FROM AUTHOR]

Introduction: The main aims of this study were to investigate autonomic nervous system (ANS) and arterial oxygen saturation (SpO2) responses to simulated altitude in males and females, and to determine the association between maximal oxygen uptake (VO2max) and these responses. Materials and Methods: Heart rate variability (HRV) and SpO2 were monitored in a resting supine position during Preliminary (6 min normoxia), Hypoxia (10 min, fraction of inspired oxygen (FiO2) of 9.6%, simulated altitude ~6,200 m) and Recovery (6 min normoxia) phases in 28 males (age 23.7 ± 1.7 years, normoxic VO2max 59.0 ± 7.8 ml.kg−1.min−1, body mass index (BMI) 24.2 ± 2.1 kg.m−2) and 30 females (age 23.8 ± 1.8 years, VO2max 45.1 ± 8.7 ml.kg−1.min−1, BMI 21.8 ± 3.0 kg.m−2). Spectral analysis of HRV quantified the ANS activity by means of low frequency (LF, 0.05–0.15 Hz) and high frequency (HF, 0.15–0.50 Hz) power, transformed by natural logarithm (Ln). Time domain analysis incorporated the square root of the mean of the squares of the successive differences (rMSSD). Results: There were no significant differences in SpO2 level during hypoxia between the males (71.9 ± 7.5%) and females (70.8 ± 7.1%). Vagally-related HRV variables (Ln HF and Ln rMSSD) exhibited no significant differences between sexes across each phase. However, while the sexes demonstrated similar Ln LF/HF values during the Preliminary phase, the males (0.5 ± 1.3) had a relatively higher (p = 0.001) sympathetic activity compared to females (−0.6 ± 1.4) during the Hypoxia phase. Oxygen desaturation during resting hypoxia was significantly correlated with VO2max in males (r = −0.45, p = 0.017) but not in females (r = 0.01, p = 0.952) and difference between regression lines were significant (p = 0.024). Conclusions: Despite similar oxygen desaturation levels, males exhibited a relatively higher sympathetic responses to hypoxia exposure compared with females. In addition, the SpO2 response to resting hypoxia exposure was related to maximal aerobic capacity in males but not females. [ABSTRACT FROM AUTHOR]

Purpose: To find the shortest, acceptable stabilization period before recording resting, supine ultra-short-term Ln RMSSD and heart rate (HR). Method: Thirty endurance-trained male athletes (age 24.1 ± 2.3 years, maximal oxygen consumption (VO2max) 64.1 ± 6.6 ml·kg-1·min-1) and 30 male students (age 23.3 ± 1.8 years, VO2max 52.8 ± 5.1 ml·kg-1·min-1) were recruited. Upon awaking at home, resting, supine RR intervals were measured continuously for 10 min using a Polar V800 HR monitor. Ultra-short-term Ln RMSSD and HR values were calculated from 1-min RR interval segments after stabilization periods from 0 to 4 min in 0.5 min increments and were compared with reference values calculated from 5-min segment after 5-min stabilization. Systematic bias and intraclass correlation coefficients (ICC) including 90% confidence intervals (CI) were calculated and magnitude based inference was conducted. Results: The stabilization periods of up to 30 s for athletes and up to 60 s for students showed positive (possibly to most likely) biases for ultra-short-term Ln RMSSD compared with reference values. Stabilization periods of 60 s for athletes and 90 s for students showed trivial biases and ICCs were 0.84; 90% CI 0.72 to 0.91, and 0.88; 0.79 to 0.94, respectively. For HR, biases were trivial and ICCs were 0.93; 0.88 to 0.96, and 0.93; 0.88 to 0.96, respectively. Conclusion: The shortest stabilization period required to stabilize Ln RMSSD and HR was set at 60 s for endurance-trained athletes and 90 s for university students. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine the acute effects of soccer specific fatigue on muscular and neuromuscular function in male youth soccer players. Elite soccer players (n = 20; age 15.7 ± 0.5 y; body height 177.75 ± 6.61 cm; body mass 67.28 ± 8.29 kg) were measured before and after soccer specific exercise (SAFT90). The reactive strength index (RSI) was determined by a drop jump test, leg stiffness (LS) by a 20 sub-maximal two-legged hopping test, and a functional hamstring to quadriceps strength ratio from isokinetic concentric and eccentric strength of the dominant and non-dominant leg (measured at angular velocities of 1.05 rad · s−1 and 3.14 rad · s−1). Metabolic response to the SAFT90 was determined by blood lactate and perceived exertion was assessed by the Borg scale. After simulated match play, a significant decrease in absolute LS (t = 4.411; p < 0.001; ω2 = 0.48) and relative LS (t = 4.326; p < 0.001; ω2 = 0.49) was observed and the RSI increased significantly (t = 3.806; p = 0.001; ω2 = 0.40). A reduction in LS found after the SAFT90 indicates possible reduction in dynamic knee stabilization. However, if we consider the changes in other observed variables, the present study did not clearly confirm that fatigue induced by a soccer specific protocol increased the risk of ACL and hamstring injury. This may be attributed to the simulated rather than actual match play used in the present study. [ABSTRACT FROM AUTHOR]

Background: It is well known that vigorous physical activity induces functional changes in cardiac autonomic nervous system (ANS) activity that is sustained several hours after exercise. However, data related to ANS recovery after more extreme endurance events, such as skyrunning marathons, are still lacking. Objective: The aims of this prospective cohort study were firstly, to determine the ANS response to a SkyMarathon, and secondly, to examine correlates of run performance. Methods: Ten male skyrunners aged 37.2 ± 9.2 years were recruited. The race was performed at a mean intensity 85.4 ± 3.7% of heart rate reserve, and lasted for 338 ± 38 min. Morning supine heart rate variability was measured at 10, 2 and 1 days before race, on the race day, at 5 min intervals for 30 min immediately post-race and then at 5 h and 30 h post. High-frequency power (HF, 0.15-0.50 Hz), low-frequency power (LF, 0.05-0.15 Hz), and square root of the mean of the squares of the successive differences (RMSSD) were calculated and transformed by natural logarithm (Ln). Results: Sympathovagal balance (Ln LF/HF) was most likely increased above baseline during the 30 min post-race and returned to baseline by 5 h. Vagal activity (Ln RMSSD and Ln HF) was most likely decreased below baseline during the 30 min post-race and 5 h of post-race, and recovered to baseline by 30 h. Race time correlated with resting heart rate (r = .81), body mass index (r = .73), maximal power output (r = -.70), and maximal oxygen uptake (r = -.61). Conclusions: The SkyMarathon elicited disturbances in ANS activity, with relative sympathetic activity increased up to 5 h post-race and vagal activity recovering by 30 h. Resting heart rate, body mass index, maximal power output, and maximal oxygen uptake were associated with SkyMarathon performance prediction. [ABSTRACT FROM AUTHOR]

Backround: High performance is also associated with specific ranges in somatic parameters depending on the sporting discipline. The development and maintenance of these parameters is supported primarily by the conditioning sessions players are exposed to across the various phases of the season. Objective: The aim of the study was to monitor the changes in the body composition of an entire team of elite players during a conditioning program. Method: The study included a total of 25 elite, Czech Republic, premier league (ELH) ice hockey players (24.6±5.0 years). The measured parameters included the following: body mass (BM), body fat (BF), fat free mass (FFM) and segmental analysis BF. These parameters were measured at the beginning and at the end of specific phases of the conditioning program, with four measurements taken in total. Results: Compared with the pre conditioning phase measurement, percentage of body fat decreased by 1.8 to 2.3 % (p<.05, η2=.06) during the conditioning phase which was analyzer dependent. Extracellular mass decreased by 2 kg (p<.05, η2=.04), while there was a 2.9 kg (p<.05, η2=.14) increase in intracellular mass. There were also changes in the segmental distribution of body fat, with a decrease of 1.4 to 1.9% (p<.05, η2 =.07) in the lower limbs and a decrease of 2.9% (p<.05, η2=.07) in the trunk. No changes were observed in the upper limbs. Conclusion: These results indicate that the conditioning program had a positive effect on the somatic parameters in the players. There was a decrease in fat mass and increase in muscle mass, which creates another precondition for further development of the strength performance. [ABSTRACT FROM AUTHOR]

Background: A reduction in the inspired oxygen fraction (FiO2) induces a decline in arterial oxygen saturation (SpO2) and changes of heart rate variability (HRV). It has been shown that SpO2 and HRV responses to similar levels of acute normobaric hypoxia are inter-individual variable. Variable response may be influenced by normoxia reached maximal oxygen uptake (VO2max) value. Objective: The primary aim was to assess HRV and the SpO2 response to hypoxia, and examine the association with normoxic VO2max. Methods: Supine HRV and SpO2 were monitored during normobaric hypoxia (FiO2 = 9.6%) for 10 minutes in 28 subjects, aged 23.7 ± 1.7 years. HRV was evaluated by using both spectral and time domain HRV analysis. Low frequency (LF, 0.05-0.15 Hz) and high frequency (HF, 0.15-0.50 Hz) power together with square root of the mean of the squares of the successive differences (rMSSD) were calculated and transformed by natural logarithm (Ln). Based on the SpO2 in hypoxia, subjects were divided into Resistant (RG, SpO2 ≥ 70.9%, n = 14) and Sensitive (SG, SpO2 < 70.9%, n = 14) groups. Perceived hypoxia tolerance was self-scored on a 4-level scale. Results: VO2max was higher in SG (62.4 ± 7.2 ml. kg-1. min-1) compared with RG (55.5 ± 7.1 ml. kg-1. min-1, p = .017, d = 0.97). A significant relationship (r = -.45, p = .017) between hypoxicnormoxic difference in SpO2 and normoxic VO2max level was found. Vagal activity (Ln rMSSD) was significantly decreased (SG: p < .001, d = 2.64; RG: p < .001, d = 1.22), while sympathetic activity (Ln LF/HF) was relatively increased (p < .001, d = -1.40) in only the SG during hypoxia. Conclusions: Results show that subjects with a higher aerobic capacity exhibited a greater decline in SpO2, accompanied by greater autonomic cardiac disturbances during hypoxia. The SpO2 reduction was associated with perceived hypoxia comfort/discomfort. The hypoxia discomfort state was accompanied by a greater withdrawal in cardiac vagal activity. [ABSTRACT FROM AUTHOR]

This cross-sectional study compared somatic, endurance performance determinants and heart rate variability (HRV) profiles of professional soccer players divided into different age groups: GI (17-19.9 years; n = 23), GII (20-24.9 years; n = 45), GIII (25-29.9 years; n = 30), and GIV (30-39 years; n = 26). Players underwent somatic and HRV assessment and maximal exercise testing. HRV was analyzed by spectral analysis of HRV, and high (HF) and low (LF) frequency power was transformed by a natural logarithm (Ln). Players in GIV (83 ± 7 kg) were heavier (p < 0.05) compared to both GI (73 ± 6 kg), and GII (78 ± 6 kg). Significantly lower maximal oxygen uptake (VO2max, ml•kg-1•min-1) was observed for GIV (56.6 ± 3.8) compared to GI (59.6 ± 3.9), GII (59.4 ± 4.2) and GIV (59.7 ± 4.1). All agegroups, except for GII, demonstrated comparable relative maximal power output (Pmax). For supine HRV, significantly lower Ln HF (ms2) was identified in both GIII (7.1 ± 0.8) and GIV (6.9 ± 1.0) compared to GI (7.9 ± 0.6) and GII (7.7 ± 0.9). In conclusion, soccer players aged >25 years showed negligible differences in Pmax unlike the age group differences demonstrated in VO2max. A shift towards relative sympathetic dominance, particularly due to reduced vagal activity, was apparent after approximately 8 years of competing at the professional level. [ABSTRACT FROM AUTHOR]

Background: In order to optimize training in soccer, knowledge about the specific position fitness demands and characteristics is required. Objective: The aim of the study was to determine whether there are position specific differences in somatic, cardiorespiratory and autonomic cardiac profiles of professional senior Czech soccer players. Methods: All players (N = 120) were divided into six groups according to field positions: goalkeeper (GK; n = 11), external defenders (ED; n = 15), central defenders (CD; n = 18), external midfielders (EM; n = 18), central midfielders (CM; n = 24) and forwards (F; n = 34). Players underwent anthropometrical and heart rate variability (HRV) assessment, and a maximal incremental running test in order to obtain maximal oxygen uptake (VO2max) and heart rate. HRV variables were transformed using the natural logarithm (Ln). Results: GK and CD were significantly (p = .005) heavier than ED, EM, CM, and F; while F were significantly (p = .026) heavier than CM and EM. GK and CD were significantly (p = .008) taller than ED, EM, CM, F; and EM were significantly (p = .041) shorter than CM and F. The only significant (p = .043) difference in percentage of body fat was observed in CD compared with CM. A significantly (p = .021) lower VO2max was observed for GK compared with ED, CD, EM, CM, and F. Supine HRV was significantly (p = .039) lower for Ln LF/HF in GK compared with F. Standing HRV was significantly (p = .03) lower for Ln LF in CD compared with both ED and F, significantly (p = .028) higher for Ln LF/HF in ED compared with CD and EM. Conclusions: In soccer, specific positions are associated with different height, body mass and aerobic capacity. A lower VO2max and vagal activity in GK compared with other playing positions may not be considered as disadvantage for performance in this specific playing position. [ABSTRACT FROM AUTHOR]

Background: Training preparation in soccer is thought to improve body composition and performance level, especially the maximal aerobic capacity (VO2max). However, an enhancement in performance may be attenuated by the increase of fatigue. Heart rate variability (HRV) as a non-invasive index of autonomic nervous system (ANS) activity has been considered to be a sensitive tool in fatigue assessment. Objective: This study was focused to evaluate the response of ANS activity and morpho-physiological parameters to eight week training preparation. Methods: Study included 12 trained soccer players aged 17.2 ± 1.2 years. Athletes underwent pre- and post-preparation testing that included the ANS activity assessment by spectral analysis of HRV in supine and upright position. Further, body composition was analyzed via electrical bio-impedance method and physiological parameters were assessed during maximal stress tests. ANS activity and subjective feeling of fatigue was assessed continuously within subsequent weeks of preparation. Results: No significant differences in all HRV variables within weeks were found. Pre vs. post analyses revealed a significant (p < .05) increase in body weight, fat free mass, body mass index, and peak power. A significant decline in mean maximal heart rate (HR) and resting HR at standing was identified at the end of preparation. Since no significant changes between pre- post-preparation in the mean VO2max occurred, the positive correlation between the individual change in VO2max and the vagally related HRV [supine LnHF (r = .78), Ln rMSSD (r = .63), and the standing LnHF (r = .73, p < .05)] was found. Conclusions: This study showed that an 8 week training program modified particularly fat free mass and short-term endurance, whereas both the autonomic cardiac regulation and the feeling of fatigue remained almost unaffected. Standing position seems to be more sensitive in terms of the HR response in relation to fatigue perception than supine. [ABSTRACT FROM AUTHOR]

Objectives. To investigate the relationship between the body composition and regional bone mineral density (BMD) in postmenopausal women according to years since menopause (YSM). Methods. A total of 167 postmenopausal women with a mean age of 62.91 ± 5.09 years participated in this cross-sectional study. The average YSM was 11.96 ± 6.28 years. We used the DXA Lunar Prodigy Primo™ device to assess the body composition parameters [body fat mass (BFM) and lean body mass (LBM)] and the BMD of the lumbar spine, proximal femur and total body. Results. The LBM was a stronger predictor of the proximal femur BMD than BFM in 1-10 YSM category, whereas the BFM was a stronger predictor of the proximal femur BMD than LBM in 11-20 and 21-30 YSM categories. The BMD of the lumbar spine showed a similar trend. A significant relationship was found between BMD of L1-L4 and LBM in 1-10 YSM category ( r = 0.26; p < 0.05). BFM was significantly associated with BMD of L1-L4 in 11-20 YSM category ( r = 0.25; p < 0.05). Significant relationships were found between total femur BMD and LBM in 1-10 YSM ( r = 0.27; p < 0.05) and 11-20 YSM category ( r = 0.25; p < 0.05). BFM was significantly associated with total femur BMD only in 11-20 YSM category ( r = 0.40; p < 0.05). Conclusion. The relationships between BMD and body composition are dependent on YSM and vary between selected segments. [ABSTRACT FROM AUTHOR]

Copyright of Acta Universitatis Palackianae Olomucensis. Gymnica is the property of Palacky University in Olomouc and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Universitatis Palackianae Olomucensis. Gymnica is the property of Palacky University in Olomouc and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Universitatis Palackianae Olomucensis. Gymnica is the property of Palacky University in Olomouc and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Universitatis Palackianae Olomucensis. Gymnica is the property of Palacky University in Olomouc and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Universitatis Palackianae Olomucensis. Gymnica is the property of Palacky University in Olomouc and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Universitatis Palackianae Olomucensis. Gymnica is the property of Palacky University in Olomouc and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Hydrogen-rich water (HRW) supplementation has been shown to have an antifatigue effect across different modes of exercise. However, its effect on repeated sprint performance is unknown. The aim of this study was to assess the effect of pre-exercise HRW consumption on repeated sprint performance, lactate, and perceptual responses using a repeated sprint protocol. This randomized, double blinded, placebo controlled, crossover study included 16 professional, male soccer players aged 18.8 ± 1.2 years. Athletes performed two indoor tests, particularly 15 × 30 m track sprints interspersed by 20 s of recovery, separated by a 1-week washout period. Sprint time was measured at 15 m and 30 m. Ratings of perceived exertion were assessed immediately after each sprint, and post-exercise blood lactate concentration was measured after the last sprint. There were significantly faster sprint times after HRW consumption compared with placebo at 15 m for the 14th and 15th sprints, representing improvements in time of 3.4% and 2.7%, respectively. Sprint time at 30 m also significantly improved by 1.9% in the HRW group in the last sprint. However, neither lactate concentrations nor ratings of perceived exertion were significantly different between HRW and placebo. Pre-exercise HRW supplementation is associated with an increased ability to reduce fatigue, especially during the later stages of repeated sprint exercise. [ABSTRACT FROM AUTHOR]

The article offers a case study which examines the changes in the autonomic nervous system (ANS) activity with the subjective feeling of fatigue from the 67 hours after a race in 31-year-old male amateur athlete. The study shows that the ANS activity was completely restored by the 44th hour of post-marathon recovery. It added that the high level of subjectively perceived fatigue remained in the entire recovery period monitored and was not correlated to the ANS activity.

Copyright of Acta Universitatis Palackianae Olomucensis. Gymnica is the property of Palacky University in Olomouc and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Universitatis Palackianae Olomucensis. Gymnica is the property of Palacky University in Olomouc and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Universitatis Palackianae Olomucensis. Gymnica is the property of Palacky University in Olomouc and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Universitatis Palackianae Olomucensis. Gymnica is the property of Palacky University in Olomouc and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Universitatis Palackianae Olomucensis. Gymnica is the property of Palacky University in Olomouc and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article discusses a study conducted in the Czech Republic, published in the journal "Central European Journal of Public Health" that examines the impact of COVID-19 pandemic restrictions on pediatric competitive athletes. The study found that temporary restrictions on leisure and organized sports activities led to an increase in height, weight, BMI, and power output among the athletes, but a reduction in power output per kilogram of body weight, particularly among older age groups.

The prevalence of cardiovascular disease (CVD) is rising worldwide, remaining the major cause of death in developed countries. Polyphenols have been shown to have cardioprotective properties; however, their impact on iron bioavailability and potential impact on other aspects of health is unclear. A systematic review was undertaken to evaluate the current status of the relationship between habitual polyphenol consumption, iron status, and circulating biomarkers of CVD. Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) 2009 guidelines, searches were performed across 5 electronic databases (PubMed, Cochrane Library, Scopus, Web of Science, and CINAHL) to identify randomized controlled trials which investigated the effects of polyphenol consumption on inflammatory markers, serum lipid profile, and iron absorption and bioavailability. In total, 1174 records were identified, with only 7 studies meeting the inclusion criteria. The selected studies involved 133 participants and used a variety of foods and supplements, including olive oil and cherries, rich in polyphenols including hydroxytyrosol, quercetin, and resveratrol, as well as catechin enriched drinks. The duration of the studies ranged from between 56 and 145 days, with total polyphenolic content of the food items and supplements ranging from 45 to 1015 mg (per 100 g). Polyphenols did not appear to interfere with iron status, and most studies reported improvements in inflammatory markers and lipid profile. While these results are promising, the limited number of studies and considerable heterogeneity across the interventions support the need for more extensive trials assessing the relationship between polyphenol intake, iron bioavailability, and CVD risk. [ABSTRACT FROM AUTHOR]

An abstract of the article "THE CHANGES OF HEART RATE VARIABILITY AFTER SIX-MONTH LONG AEROBIC DANCE- OR STEP-DANCE PROGRAM IN WOMAN 40-65 YEARS OLD: THE INFLUENCE OF DIFFERENT ADHERENCES, INTENSITY AND INITIAL LEVELS," by Aleš Jakubec, Pavel Stejskal, and colleagues is presented.

An abstract of the article "MONITORING OF AUTONOMIC NERVOUS SYSTEM ACTIVITY DURING RECOVERY PERIOD AFTER MARATHON RUN BY SPECTRAL ANALYSIS OF HEART RATE VARIABILITY: A CASE STUDY," by Michal Botek, Pavel Stejskal, and Filip Neuls is presented.

Purpose: The purpose of the study was to determine the intraocular pressure response to normobaric hypoxia and the consequent recovery under additional well-controlled ambient conditions. Second, the study attempted to determine if the intraocular pressure changes were dependent on its baseline, initial heart rate, sex and arterial oxygen saturation. Methods: Thirty-eight visually healthy volunteers (23 women and 15 men) of an average age 25.2 ± 3.8 years from 49 recruited participants met the inclusion criteria and performed the complete test. Initial intraocular pressure (baseline), heart rate, and arterial oxygen saturation were measured after 7 min of rest under normal ambient conditions at an altitude 250 m above sea level. Each subject then underwent a 10 min normobaric hypoxic exposure and a subsequent 7 min recovery under normoxic conditions. Within hypoxic period, subjects were challenged to breathe hypoxic gas mixture with fraction of inspired oxygen of 9.6% (~6.200 m above sea level). Intraocular pressure and arterial oxygen saturation were re-measured at 4 and 10 min during the hypoxia and at 7 min after hypoxia termination. Results: Intraocular pressure increased in 1.2 mmHg ± 1.9 mmHg and 0.9 mmHg ± 2.3 mmHg at 4 and 10 min during the hypoxic period and returned approximately to the baseline at 7 min of recovery. The influence of sex was not statistically significant. The arterial oxygen saturation decreased in 14.9 ± 4.2% at min 4 and 18.4 ± 5.8% at min 10 during hypoxia and returned to the resting value at 7 min of recovery. The decrease was slightly higher in the case of women if compared with men. The hypoxia induced changes in intraocular pressure were significantly correlated with the arterial oxygen saturation changes, whereas the relationship with intraocular pressure baseline and initial heart rate were insignificant. Conclusion: There was a significant increase in intraocular pressure as a response to short-term normobaric hypoxia, which returned to the baseline in 7 min after hypoxia. The increase was dependent on the induced oxygen desaturation.