The validity and reliability of a hydraulic resistance device for assessing resisted sprint time.

Introduction: The aim of this study was to assess the validity and reliability of a hydraulic resistance device (HRD) for monitoring sprint split times under different loads within and between sessions. Methods: Three 20-m sprints with low (15 N), medium-low (40 N), medium-high (50 N), and high (130 N) HRD resistance levels (loads) were performed on two separate occasions 14 days apart. Twenty-four student athletes (24.8 ± 3.8 years) participated in the first session and 13 (24.1 ± 3.2 years) of them in the second session. Resisted sprints split times over a distance of 0-20 m (t0-5, t0-10, t0-20, t5-10, t10-15, t15-20) were measured simultaneously with magnetic incremental encoder embedded in the HRD and a system of single-beam timing gates. Results: The results showed acceptable to high within session (ICC3,1 = 0.91-0.99; CV = 0.92%-3.38%) and between session (ICC3,1 = 0.82-0.99; CV = 1.62%-4.84%) reliability of HRD for measuring all split times at all loads. The minimal detectable change between sessions ranged from 3.3% at high load to 9.9% at low load. The HRD systematically underestimated timing gates times at all loads (bias = 2.01-11.08%), yet good to excellent consistency was observed between the HRD and timing gates, specifically for t0-10 and t0-20 (ICC3,k lower 95% CI = 0.84-0.99). Discussion: Due to high reliability and good validity in monitoring resisted sprint times, the HRD holds potential for practical and research applications.

Relationship between Countermovement Jump and Sprint Performance in Professional Football Players.

Objectives: The aim of this study was to assess the relationship between the countermovement jump (CMJ) and sprint performance of professional football players, and to determine which strength and speed elements assessed by the CMJ translate into effective running. Methods: The research sample comprised 87 male professional football players (age 23.7 ± 4.20 years; body mass 82.33 ± 6.56 kg; body height 1.86 ± 0.05 m) who performed the CMJ on a dual-force platform, as well as the 30 m sprint test. The time and velocity of the run were recorded by photocells at 0, 5, 10, and 30 m of the distance. Results: No significant differences were noted in the time or velocity of the sprint over the initial 5 m between the groups of football players with a higher and lower braking rate of force development (RFD) in the CMJ (p > 0.05). However, at subsequent intervals (5-10 m and 10-30 m), players with a higher braking RFD achieved significantly better time and velocity than those with a lower RFD. Significant correlations in the group with a lower braking RFD between the CMJ and sprint variables occurred in the propulsion phase of the CMJ and most of them were in the first interval (0-5 m). In the group with a higher braking RFD, significant relationships were visible in both the propulsion (concentric) and braking (eccentric) phases of the CMJ, mainly during the second and third intervals of the sprint test. Conclusions: The noted observations may suggest that the relationship between strength and running performance is more complex than previously indicated, and that higher strength in the CMJ does not fully correlate with better sprinting. Therefore, it has been hypothesized that training aimed at generally increasing strength may not always be fully beneficial for running performance in football players and hence specific training guidelines are suggested for targeted strengthening of the required muscle performance characteristics. This may possibly contribute to reducing the unnecessary muscle overload during both training and matches, thereby preventing sports-related injuries.

Let's include the ladies: Do morphology-performance relationships vary between sexes in lizards?

An animal's morphology influences its ability to perform essential tasks, such as locomoting to obtain prey or escape predators. While morphology-performance relationships are well-studied in lizards, most conclusions have been based only on male study subjects, leaving unanswered questions about females. Sex-specific differences are important to understand because females carry the bulk of the physiological demands of reproduction. Consequently, their health and survival can determine the fate of the population as a whole. To address this knowledge gap, we sampled introduced populations of common wall lizards (Podarcis muralis) in Ohio, USA. We measured a complete suite of limb and body dimensions of both males and females, and we measured sprint speeds while following straight paths and curved paths on different substrates. Using a multivariate statistical approach, we identified that body dimensions relative to snout-to-vent length in males were much larger compared to females and that body dimensions of P. muralis have changed over time in both sexes. We found that sprint speed along curved paths increased with relative limb size in both males and females. When following straight paths, male speed similarly increased as body dimensions increased; conversely, female speed decreased as body dimensions increased. Female sprint speed was also found to have less variation than that of males and was less affected by changes in body size and hindfoot length compared to males. This study thus provides insights into how selective pressures might shape males and females differently and the functional implications of sexual dimorphism.

Hamstrings on focus: Are 72 hours sufficient for recovery after a football (soccer) match? A multidisciplinary approach based on hamstring injury risk factors and histology.

This study aimed to assess acute and residual changes in sprint-related hamstring injury (HSI) risk factors after a football (soccer) match, focusing on recovery within the commonly observed 72-h timeframe between elite football matches. We used a multifactorial approach within a football context, incorporating optical and ultrastructural microscopic analysis of BFlh (biceps femoris long head) muscle fibres, along with an examination of BFlh fibre composition. Changes in sprint performance-related factors and HSI modifiable risk factors were examined until 3 days after the match (MD +3) in 20 football players. BFlh biopsy specimens were obtained before and at MD +3 in 10 players. The findings indicated that at MD +3, sprint-related performance and HSI risk factors had not fully recovered, with notable increases in localized BFlh fibre disruptions. Interestingly, match load (both external and internal) did not correlate with changes in sprint performance or HSI risk factors nor with BFlh fibre disruption. Furthermore, our study revealed a balanced distribution of ATPase-based fibre types in BFlh, with type-II fibres associated with sprint performance. Overall, the results suggest that a 72-h recovery period may not be adequate for hamstring muscles in terms of both HSI risk factors and BFlh fibre structure following a football match.

Pesticide residues in European sediments: A significant concern for the aquatic systems?

The presence of pesticide residues in waterbed sediments poses a significant concern for aquatic ecosystems' health. This study examined pesticide contamination in sediments of 38 water bodies, embedded in agricultural-dominated regions, across eight European countries. Three indicators were targeted: occurrence, type, and concentrations of multiple pesticide residues in sediments. 196 pesticide residues (including degradation products) were tested in the sediment samples. The analytical results showed that only one sample was 'pesticide-free', three samples contained a single pesticide residue, and the remaining 34 samples contained mixtures of residues. Overall, 99 different residues were found in the sediments, with a maximum of 48 in a single sample. Twenty-seven out of the 99 detected residues were not approved for agricultural use at the time of sampling. The numbers of detected residues and pesticide levels varied among countries. AMPA, glyphosate and DDTs were the most common residues in sediment samples with frequencies of 76, 61, and 52%, respectively. The sediments from the Czech Republic had the highest pesticide concentrations, with total pesticide concentrations ranging between 600 and 1200 µg kg-1. The lowest total pesticide concentrations were found in Slovenia, Switzerland, Croatia, and Denmark, ranging between 80 and 120 µg kg-1. Sediments presented a mix of non-persistent and persistent compounds. Twelve of the detected pesticides are very persistent/stable in sediments, raising concerns about the long-term impacts of pesticides. Our study on the distribution of pesticide residues in European sediments provides valuable insights into the extent of pesticide contamination and possible risks of pesticides to water bodies' health. It also underlines the need for monitoring, research, and policy efforts to mitigate the impacts of pesticides, and to evaluate potential risks of re-use of dredged sediments.

Dose-response effects of caffeine during repeated cycling sprints in normobaric hypoxia to exhaustion.

PURPOSE: With limited studies exploring the dose-response of caffeine consumption on repeated sprint ability in hypoxia, this study aimed to determine the optimal caffeine dose (low, moderate or high) during repeated sprints in hypoxia to exhaustion. METHODS: On separate visits, twelve active males randomly performed four experimental trials in normobaric hypoxia (inspired oxygen fraction: 16.5 ± 0.2%). Participants ingested placebo (PLA) or caffeine capsules (3, 6 or 9 mg/kg or LOW, MOD and HIGH, respectively) 1 h before exercise and then underwent a repeated cycling sprint test (10 s sprint/20 s active recovery) to exhaustion. Total sprint number and work done, peak and mean power output, blood lactate concentration, cardiorespiratory and perceptual responses were recorded. RESULTS: Total sprint number was greater in MOD and HIGH compared to PLA (20 ± 7 and 18 ± 8 vs. 13 ± 4; all P < 0.05), with MOD also higher than LOW (15 ± 6; P = 0.02). Total work done was greater in MOD (111 ± 40 kJ) and HIGH (100 ± 35 kJ) compared to LOW (83 ± 29 kJ) and PLA (76 ± 25 kJ) (all P < 0.05). However, there were no significant differences in total sprint number or total work done between MOD and HIGH (all P > 0.05). Blood lactate concentration was higher in both MOD and HIGH compared to PLA (all P < 0.05). However, peak and mean power outputs, fatigue index, and ratings of perceived exertion did not differ across different caffeine dosages (all P > 0.05). CONCLUSION: A moderate dose of caffeine (6 mg/kg) is the optimal amount for enhancing repeated cycling sprint ability when compared to low and high doses in moderate normobaric hypoxia.

Raw bioelectrical data and physical performance in track and field athletes: Are there differences between the sexes in the relationship?

Objectives: The study aimed to investigate the relationship between raw bioelectrical data and physical performance in track and field athletes. Specifically, the objectives were to determine: 1) whether a regional bioelectrical impedance approach provides additional insights compared to whole-body analysis, 2) the reliability of the Levi Muscle Index (LMI) in this context, and 3) whether there are differences in these relationships between male and female athletes. Design: This study utilized a cross-sectional design involving thirty-one female athletes (mean age 21.4 ± 3.8 years) and thirty male athletes (mean age 21.1 ± 2.6 years) from track and field. On a single day, participants underwent whole-body and regional bioelectrical impedance assessments focusing on the lower limbs, alongside strength and speed performance tests. Results: The study found no significant differences in the relationship between whole-body versus regional bioelectrical impedance and performance tests. Resistance (R) demonstrated an inverse correlation, while phase angle (PhA) and Levi Muscle Index (LMI) showed direct correlations with most performance variables in track and field athletes. Significant differences were observed between male and female athletes across all parameters, with male athletes exhibiting superior performance, higher PhA and LMI values, and stronger correlation coefficients compared to females. Conclusions: In summary, this study highlights the intricate relationship between body composition and physical performance in athletes. It underscores the importance of considering sex differences and the reliability of raw bioelectrical data, whether obtained through regional or whole-body approaches, in assessing athletic performance.

Inter-individual variability in peripheral oxygen saturation and repeated sprint performance in hypoxia: an observational study of highly-trained subjects.

Individual variations in peripheral oxygen saturation (SpO2) during repeated sprints in hypoxia and their impact on exercise performance remain unclear despite fixed external hypoxic stimuli (inspired oxygen fraction: FiO2). This study examined SpO2 individual variations during repeated sprints in hypoxia and their impact on exercise performance. Thirteen highly-trained sprint runners performed 10 × 10-s cycle sprints with 30-s passive recoveries in normobaric hypoxia (FiO2: 0.150). Mean power output (MPO), post-sprint SpO2, and heart rate for each sprint were assessed. Sprint decrement score (Sdec), evaluating fatigue development, was calculated using MPO variables. Participants were categorized into a high saturation group (HiSat, n = 7) or a low saturation group (LowSat, n = 6) based on their mean post-sprint SpO2 (measured 10-15 s after each sprint). Individual mean post-sprint SpO2 ranged from 91.6% to 82.2%. Mean post-sprint SpO2 was significantly higher (P < 0.001, d = 1.54) in HiSat (89.1% ± 1.5%) than LowSat (84.7% ± 1.6%). A significantly larger decrease in Sdec (P = 0.008, d = 1.68) occurred in LowSat (-22.3% ± 2.3%) compared to HiSat (-17.9% ± 2.5%). MPO (P = 0.342 d = 0.55) and heart rate (P = 0.225 d = 0.67) did not differ between groups. There was a significant correlation (r = 0.61; P = 0.028) between SpO2 and Sdec. In highly-trained sprint runners, individual responses to hypoxia varied widely and significantly affected repeated sprint ability, with greater decreases in SpO2 associated with larger performance alterations (i.e., larger decrease in Sdec).

The Determinants of Maximal Speed Adaptation During Preseason in Subelite Female Australian Rules Footballers.

PURPOSE: Maximal speed is an important physical-fitness attribute for female Australian footballers. The effects of sprint training, maximal strength, and technical training have been reported in laboratory studies. However, no study has determined the combined effect and relative contribution of these training modalities on maximal speed adaptation in situ. Therefore, the aim of this study was to determine the training factors affecting maximal speed adaptation during a preseason in subelite female Australian Rules footballers. METHODS: Maximal speed during field training, predicted 1-repetition maximum (1RM) for box squat and hip thrust, and sprint biomechanics were assessed during early and late preseason (∼9 wk apart) in 15 female subelite Australian Rules Football players (age 20 [3] y). On-field training volume and intensity (total distance, high-speed running, very-high-speed running, and maximal speed) were determined using a Global Positioning System. A multivariate regression model was used to determine the factors associated with changes in maximal speed across the preseason. RESULTS: The preseason training program had a small effect on maximal speed and large to very large effects on strength and sprint biomechanics. The multivariate regression with the greatest fit (P < .001, R2 = .939) included change in estimated 1RM box squat (ß = -0.63), total distance per week (ß = -0.55), and change in hip projection (ß = 0.16) as factors. Multivariate regression of biomechanical factors (P = .044, R2 = .717) and maximal strength factors (P = .003, R2 = .676) were also significant. CONCLUSION: The development of maximal speed across a preseason is dependent on (1) total distance per week, (2) maximal strength adaptation, and (3) sprint technique adaptation in female subelite Australian rules football players.

Effects of low-volume court-based sprint interval training on anaerobic capacity and sport-specific performance in competitive tennis players.

Sprint interval training (SIT) is a potent exercise strategy to enhance athletes' anaerobic capacity in a time-efficient manner. This study aimed to investigate the impact of low-volume, court-based SIT on the anaerobic capacity and sport-specific performance in competitive tennis players. Twenty-four competitive collegiate tennis players were randomly assigned to either the SIT group (n = 12; three sessions per week of court-based repeated-sprint training) or the traditional endurance training (ET) group (n = 12; three sessions per week of 45-min continuous treadmill running, n = 12) for a 6-weeks intervention. Baseline and post-intervention assessments included the Wingate Anaerobic Test, elimination rate of blood lactate (BLAer), tennis-specific repeated sprint ability (RSA), and the Yo-Yo Intermittent Recovery Test Level 2 (YoYo-IR2). The results showed that SIT group demonstrated significant improvements in peak and average power during the Wingate test (p = 0.07; p < 0.001), along with a notable increase in YoYo-IR2 performance (7.8% increase, p = 0.04). Significant decreases were observed in both mean (5.1% decrease, p = 0.02) and sum RSA time (5.2% decrease, p = 0.02) in the tennis-specific RSA assessments. Additionally, the SIT group showed significantly higher effective training time and TRIMP in the 90-100% HRmax zone compared to the ET group (p < 0.01). This study underscores the potential benefits of low-volume, court-based SIT in enhancing anaerobic capacity and sport-specific performance in competitive tennis players, in comparison to traditional ET.

Effect of eight-week high-intensity interval training versus moderate-intensity continuous training programme on body composition, cardiometabolic risk factors in sedentary adolescents.

Objectives: This study aimed to assess and compare the effect of an 8-week high-intensity interval training (HIIT) or moderate-intensity continuous training (MICT) programme on body composition and cardiovascular metabolic outcomes of sedentary adolescents in China. Methods: Eighteen sedentary normal-weight adolescents (age: 18.5 ± 0.3 years, 11 females) were randomized into three groups. HIIT group protocol consisted of three sessions/week for 8-week of "all out" sprints to reach 85%-95% of HRmax, and MICT group protocol undertook three sessions/week for 8-week of continuous running to reach 65%-75% of HRmax. The control group resumed normal daily activities without any intervention. Blood pressure and body composition were measured, and fasting blood samples were obtained at baseline and 48 h post-trial. Mixed-design ANOVA analysis was employed followed by post hoc t-tests and Bonferroni alpha-correction was used to evaluate interaction, between-group, and within-group differences, respectively. Results: Results indicated that HIIT and MICT similarly affected body fat mass (p = 0.021, ES = 0.19; p = 0.016, ES = 0.30, respectively), body fat percentage (p = 0.037, ES = 0.17; p = 0.041, ES = 0.28, respectively), visceral fat area (p = 0.001, ES = 0.35; p = 0.003, ES = 0.49, respectively) of body composition. A positive outcome was observed for waist/hip ratio (p = 0.033, ES = 0.43) in HIIT, but not MICT (p = 0.163, ES = 0.33). No significant differences were found between groups for any clinical biomarkers. However, pairwise comparison within the group showed a significant decrease in systolic blood pressure (p = 0.018, ES = 0.84), diastolic blood pressure (p = 0.008, ES = 1.76), and triglyceride (p = 0.004, ES = 1.33) in HIIT, but no significant differences were found in the MICT and Control group. Conclusion: Both 8-week HIIT and MICT programmes have similar positive effects on reducing body fat mass, fat percentage, and visceral fat area. However, sedentary adolescents may have limited scope to decrease insulin resistance after these 8-week interventions. Notably, the 8-week HIIT intervention was highly effective in increasing cardiometabolic health compared to the MICT. The exercise intensity threshold value and metabolic outcomes of high-intensity interval sprints should be explored further to extend the long-term benefit in this cohort.

Effects of Pull-Up Training on 50-Meter Freestyle Swimming Performance: A Preliminary Analysis.

This study examined the impact of incorporating pull-up exercises into the training routines of competitive swimmers on their performance outcomes. Eight swimmers (average age 21 ± 6.7 years, height 178 ± 5.3 cm, body mass 73 ± 7.0 kg) were selected and participated in a 10-week intervention, during which pull-up exercises were added to their regular strength training sessions. Performance was evaluated through tests measuring the sprint start speed and 50-meter freestyle swim times before and after the intervention. Statistical analyses showed significant improvements in swimming explosive strength, as measured by a 15-meter time trial (p = 0.014). In addition, resistance to explosive strength, as indicated by total time in a 50-meter time trial, improved significantly (p = 0.008), particularly in the first 25 meters (p = 0.014), although not in the second 25 meters (p = 0.078). These findings highlight the critical role of upper body strength and power in enhancing swimming performance, especially in sprint events. In conclusion, incorporating pull-up exercises into training regimens appears promising for improving upper body strength and power among swimmers. Future research should address the study's limitations by using larger, more homogeneous samples and more rigorously controlling variables such as age, gender, and training schedules. These efforts could provide clearer insights into the effectiveness of pull-up exercises in optimizing swimming performance, particularly in sprint disciplines.

Variations in strength-speed-power performance across the season: do true changes occur in elite rugby players?

This study aimed to determine, through the use of a highly sensitive statistical tool, whether real changes in performance were present; and compare the rates of meaningful variations in strength, speed, and power parameters at different time-points during the competitive season in national team rugby players. Thirty-two players were assessed 5 times across the season using the following tests: squat jump and countermovement jump tests; 30-m sprint velocity; and one-repetition maximum (1RM) in the half-squat and bench-press exercises. A repeated-measures analysis of variance was conducted to test for differences between successive time-points. Individual coefficients of variation values were used to set target scores for post-measurements and examine whether changes in performance parameters were greater than the natural test variance, thus providing an indication of whether "true changes" occurred. No significant changes were detected in the vertical jump height, 1RM measures, and sprint velocity and momentum throughout the 11-month period (P > 0.05). True changes occurred much more frequently for strength-power measures than for sprint velocity and momentum. Elite rugby union players did not exhibit significant variations in neuromuscular performance across the competitive period, when a group-based analysis was conducted. However, at the individual level, "true changes" in strength-power-(but not in speed-) related qualities were consistently observed over the competitive season.

Comparative analysis of standard and contrast elastic resistance band training effects on physical fitness in female adolescent handball players.

This study aimed to compare the effects of two elastic band 10-week training programmes on the athletic performance in adolescent female handball players. Participants aged 16.0 ± 0.5 years were randomly assigned to control (CNT, n = 12), standard elastic band (SEB, n = 12), or contrast elastic band (CEB, n = 12) programmes, each performed twice a week supplementing the regular training. The sprint (10 m and 20 m), modified Illinois change-of-direction test (COD), squat jump (SJ), countermovement jump (CMJ), standing long jump (SLJ), back extensor strength (BES), medicine ball throw (MBT), 1-RM bench press, 1-RM half squat, repeated sprint ability, and force-velocity (F-V) tests were measured before and after the intervention. Both CEB and SEB similarly improved sprint (p < 0.01 and p < 0.01) and COD (p < 0.001 and p < 0.01) when compared to CNT. Jumping performance improved significantly (SJ p < 0.01; CMJ p < 0.05) only in CEB, compared to CNT. Strength improved in both experimental groups (p < 0.01; ES: 0.73 < d < 1.59) compared to CNT, and there was a greater increase for CEB than SEB (p < 0.05) in the medicine ball throw (Table 3). Both CEB and SEB increased all RSA scores compared to CNT (p < 0.01; ES: 0.10 < d < 1.22), without significant difference between them. All F-V scores increased significantly in CEB and SEB compared to CNT (p < 0.01; ES: 0.45 < d < 2.47). In addition, CEB showed substantial gains in performance for PPabs, PPrel, and F0 (p < 0.001, p < 0.001 and p < 0.05, respectively) compared to SEB. Ten-week elastic band training conducted within the competitive season improved limb strength, power and F-V profile in female handball players, with a superior effect of the contrast elastic band training mode for upper-limb strength and F-V characteristics.

Effects of Acute Ingestion of Guarana (Paullinia Cupana) on Soccer Player Performance: A Randomized, Cross-over, Placebo-Controlled Study.

OBJECTIVE: To investigate the acute effects of ingesting a beverage containing guarana (Paullinia cupana) seed powder on performance during field tests related to physical capacities that are determinants of soccer performance, such as lower limb power, sprint, agility, and the capacity to carry out intermittent exercise. METHODS: The study was conducted using a randomized, crossover, and counterbalanced design, with a beverage containing guarana or placebo administered in a double-blind manner. Twenty-seven under-17 soccer players of a professional soccer club performed a battery of tests 60 min after the ingestion of guarana (3 g of the fruit seed powder) or placebo. Trials were performed with a 7-day washout period. The battery of tests included a countermovement jump test, sprints of 10 and 20 m, an Illinois agility test, and a Yo-Yo Intermittent Recovery Test level 1 (YYIR1). RESULTS: Guarana ingestion did not improve countermovement jump, sprints, or agility (p > 0.05). However, guarana ingestion increased the distance covered in the YYIR1, compared with placebo ingestion (p = 0.01). CONCLUSION: Acute ingestion of guarana improves the capacity to perform intermittent exercise in soccer players but seems to be ineffective to improve lower limb power, sprint, and agility.

Chronic Kidney Disease Stage and Cardiovascular and Mortality Events Among Older Adults: The SPRINT Trial.

Rationale & Objective: The risk implications of the Kidney Disease: Improving Global Outcomes (KDIGO) chronic kidney disease classification in older adults are controversial. We evaluated the risk of adverse outcomes in this population across categories of estimated glomerular filtration rate (eGFR) and urinary albumin-creatinine ratio (UACR). Study Design: Prospective cohort. Settings & Participants: In total, 2,509 participants aged ≥75 years in the Systolic Blood Pressure Intervention Trial (SPRINT). Exposure: KDIGO eGFR and UACR categories. We combined KDIGO categories G1 and G2, G3b and G4, as well as A2 and A3. Outcomes: Primary SPRINT outcome (composite of myocardial infarction, other acute coronary syndromes, stroke, heart failure, or death from cardiovascular causes), and all-cause death. Analytical Approach: Multivariable Cox proportional hazard models. Results: Mean age was 79.8 years, and 37.4% were female. The mean eGFR was 64.0 mL/min/1.73 m2, and the median UACR was 13.1 mg/g. In multivariable Cox proportional hazard analysis, compared with participants with eGFR ≥ 60 mL/min/1.73 m2 and UACR < 30 mg/g, there was no statistically significant difference in the risk of the primary outcome among participants with eGFR 45-59 or 15-44 mL/min/1.73 m2 and UACR < 30 mg/g. However, those with eGFR 45-59 or 15-44 mL/min/1.73 m2 and UACR ≥ 30 mg/g had higher risk of the primary outcome (HR [95% CI], 1.97 [1.27-3.04] and 3.32 [2.23-4.93], respectively). The risk for all-cause death was higher for each category of abnormal eGFR and UACR, with the highest risk observed among those with eGFR 15-44 mL/min/1.73 m2 and UACR ≥ 30 mg/g (3.34 [2.05-5.44]). Limitations: Individuals with diabetes and urine protein >1 g/day were excluded from SPRINT. Conclusion: Among older adults SPRINT participants, low eGFR without albuminuria was associated with higher mortality but not with increased risk of cardiovascular events. Additional studies are needed to evaluate an adapted chronic kidney disease stage-based risk stratification for older adults.

Using data from participants in the SPRINT trial, we evaluated the association of chronic kidney disease stage with adverse clinical outcomes among adults older than 75 years without diabetes. We found that low level of kidney function determined by a low estimated glomerular filtration rate with moderately or severely increased urine albumin excretion was associated with increased risk for cardiovascular events and all-cause mortality. However, low estimated glomerular filtration rate with normal or mildly increased urinary albumin excretion was not consistently associated with these adverse outcomes. This finding supports the need for additional studies to evaluate an age-adapted classification of chronic kidney disease to improve risk stratification among older adults.

The role of morphometric characteristics in predicting 20-meter sprint performance through machine learning.

The aim of this study was to test the morphometric features affecting 20-m sprint performance in children at the first level of primary education using machine learning (ML) algorithms. In this study, 130 male and 152 female volunteers aged between 6 and 11 years were included. After obtaining demographic information of the participants, skinfold thickness, diameter and circumference measurements, and 20-m sprint performance were determined. The study conducted three distinct experiments to determine the optimal ML technique for predicting outcomes. Initially, the entire feature space was utilized for training the ML models to establish a baseline performance. In the second experiment, only significant features identified through correlation analysis were used for training and testing the models, enhancing the focus on relevant predictors. Lastly, Principal Component Analysis (PCA) was employed to reduce the feature space, aiming to streamline model complexity while retaining data variance. These experiments collectively aimed to evaluate different feature selection and dimensionality reduction techniques, providing insights into the most effective strategies for optimizing predictive performance in the given context. The correlation-based selected features (Age, Height, waist circumference, hip circumference, leg length, thigh length, foot length) has produced a minimum Mean Squared Error (MSE) value of 0.012 for predicting the sprint performance in children. The effective utilization of correlation analysis in the selection of relevant features for our regression model suggests that the features selected exhibit robust linear associations with the target variable and can be relied upon as predictors.

Impact of Anemia on Cardiovascular Events and All-Cause Death Among Participants Who Received Intense Blood Pressure Treatment: A Secondary Analysis of SPRINT.

Background: To investigate whether anemia is associated with incident cardiovascular events and all-cause death among participants who received intensive blood pressure (BP) treatment in the Systolic Blood Pressure Intervention Trial (SPRINT). Methods: A total of 4394 participants who received intensive BP control (systolic BP < 120 mmHg) in SPRINT were included. Anemia status was self-reported. Our primary outcome was a composite of cardiovascular events, and the secondary outcome was all-cause death. Cox regression was used to compare the incidence of outcomes between participants with anemia and non-anemia. In order to balance the baseline characteristics between the 2 groups, inverse probability of treatment weighting (IPTW) was applied. Hazard ratios (HRs), along with 95% confidence intervals (CIs), were then calculated. Results: There were 4394 participants who received intensive BP control (537 participants with anemia). Participants with anemia were older (mean age 68.86 versus 67.75, p = 0.01) and more likely to be female (64.8% versus 31.8%, p < 0.001). The presence of anemia was strongly associated with composite cardiovascular events after adjusting for potential confounders (HR 1.66, 95% CI 1.18-2.34, p = 0.004). The association remained statistically significant even in the population after IPTW (HR 1.55, 95% CI 1.06-2.27, p = 0.024). The secondary outcome revealed that participants with anemia had a higher rate of all-cause death compared to those without anemia. The HR of all-cause death for participants with anemia was 1.61 (95% CI 1.00-2.57, p = 0.049) in the population after IPTW. Conclusions: Anemia appears to be an independent risk factor for composite cardiovascular events and all-cause death among participants who received intensive BP control in SPRINT. Clinical Trial Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01206062. All SPRINT anonymized data can be found at the National Heart, Lung and Blood Institute (NHLBI) Biologic Specimen and Data Repository (https://biolincc.nhlbi.nih.gov/home/).

Effects of Different Caffeine Dosages on Maximal Physical Performance and Potential Side Effects in Low-Consumer Female Athletes: Morning vs. Evening Administration.

While previous studies have explored a range of factors governing the optimal use of caffeine (CAF) in athletes, limited research has explored how time of day (TOD) affects the ergogenic effects of various CAF dosages on physical performance. This study aimed to increase knowledge about how different recommended CAF doses (3 mg/kg vs. 6 mg/kg) ingested at different TODs affected maximal high-intensity physical performance and the perception of potential side effects in female athletes. In this double-blind, randomized, and counterbalanced study, 15 low CAF consumer athletes (aged 18.3 ± 0.5 y) underwent six trials, including three testing conditions assessed across two TODs: one in the morning (08:00 a.m.) and one in the evening (06:00 p.m.). During each condition, the participants ingested either a placebo, 3 mg/kg CAF (CAF (3 mg)), or 6 mg/kg CAF (CAF (6 mg)) capsules 60 min before each test with an in-between washout period of at least 72 h. In each trial, the participants performed a countermovement jumps test (CMJ), a modified agility t test (MATT), a repeated sprint ability (RSA), a rating of perceived exertion (RPE), and finally, a CAF side effects questionnaire. Our findings indicate the absence of an ergogenic effect on CMJ, MAT, and RSA performance in the evening after administering CAF (3 mg) or CAF (6 mg) compared to a placebo. Likewise, when CAF was ingested in the morning, there was an improvement in these performances with both CAF (3 mg) and CAF (6 mg), with greater improvement observed after CAF (6 mg). Additionally, neither the CAF dosage nor the TOD had a significant effect on the RPE. The occurrence of side effects increased significantly after the evening ingestion of CAF, particularly with a moderate dose of CAF (6 mg). Our findings indicate that the effectiveness of CAF depends on the TOD and CAF dosage. When ingested in the morning, a moderate dose of CAF (6 mg), rather than CAF (3 mg), is more effective in improving short-term physical performance without affecting CAF side effects in female athletes. Nevertheless, when ingested in the evening, neither dose was sufficient to enhance short-term physical performance, and both dosages increased the incidence of CAF side effects, particularly at a moderate dose.

Hydrogen-Rich Gas Enhanced Sprint-Interval Performance: Metabolomic Insights into Underlying Mechanisms.

(1) Background: The diversity of blood biomarkers used to assess the metabolic mechanisms of hydrogen limits a comprehensive understanding of its effects on improving exercise performance. This study evaluated the impact of hydrogen-rich gas (HRG) on metabolites following sprint-interval exercise using metabolomics approaches, aiming to elucidate its underlying mechanisms of action. (2) Methods: Ten healthy adult males participated in the Wingate Sprint-interval test (SIT) following 60 min of HRG or placebo (air) inhalation. Venous blood samples were collected for metabolomic analysis both before and after gas inhalation and subsequent to completing the SIT. (3) Results: Compared with the placebo, HRG inhalation significantly improved mean power, fatigue index, and time to peak for the fourth sprint and significantly reduced the attenuation values of peak power, mean power, and time to peak between the first and fourth. Metabolomic analysis highlighted the significant upregulation of acetylcarnitine, propionyl-L-carnitine, hypoxanthine, and xanthine upon HRG inhalation, with enrichment pathway analysis suggesting that HRG may foster fat mobilization by enhancing coenzyme A synthesis, promoting glycerophospholipid metabolism, and suppressing insulin levels. (4) Conclusions: Inhaling HRG before an SIT enhances end-stage anaerobic sprint capabilities and mitigates fatigue. Metabolomic analysis suggests that HRG may enhance ATP recovery during interval stages by accelerating fat oxidation, providing increased energy replenishment for late-stage sprints.