Young Artistic Gymnasts Drink Ad Libitum Only Half of Their Fluid Lost during Training, but More Fluid Intake Does Not Influence Performance.

To examine the effect of the fluid balance on and performance in young artistic gymnasts during training under ad libitum and prescribed fluid intake conditions, eleven males (12.3 ± 2.6 years, mean ± SD) performed two 3 h identical training sessions. Participants ingested, in a random order, water equivalent to either 50% (LV) or 150% (HV) of their fluid loss. After the 3 h training, the gymnasts performed program routines on three apparatuses. The pre-exercise urine specific gravity (USG) was similar between conditions (LV: 1.018 ± 0.007 vs. HV: 1.015 ± 0.007; p = 0.09), while the post-exercise USG was lower in the HV condition (LV: 1.017 ± 0.006 vs. HV: 1.002 ± 0.003; p < 0.001). Fluid loss corresponding to percentage of body mass was higher in the LV condition (1.2 ± 0.5%) compared to the HV condition (0.4 ± 0.8%) (p = 0.02); however, the sums of the score performances were not different (LV: 26.17 ± 2.04 vs. HV: 26.05 ± 2.00; p = 0.57). Ingesting fluid equivalent to about 50% of the fluid lost, which was the amount that was drunk ad libitum during training, maintained short-term hydration levels and avoided excessive dehydration in artistic preadolescent and adolescent gymnasts. A higher amount of fluid, equivalent to about 1.5 times the fluid loss, did not provide an additional performance benefit.

A lifestyle pattern characterised by high consumption of sweet and salty snacks, sugar sweetened beverages and sedentary time is associated with blood pressure in families at risk for type 2 diabetes mellitus in Europe. The Feel4Diabetes Study.

BACKGROUND: Individuals from families at high-risk for type 2 diabetes mellitus (T2DM) are also at high risk for hypertension (HTN) and cardiovascular disease. Studies identifying lifestyle patterns (LPs) combining dietary, physical activity or sedentary variables and examining their possible role with respect to developing blood pressure (BP) are limited. The present study aimed to examine the association of different LPs with BP levels in families at high risk for T2DM in Europe. METHODS: In total, 1844 adults (31.6% males) at high-risk for T2DM across six European countries were included in this cross-sectional study using data from the baseline assessment of the Feel4Diabetes Study. BP measurements and dietary and physical activity assessments were conducted, and screen times were surveyed. LPs were revealed with principal component analysis of various data regarding diet, physical activity, screen time and smoking. RESULTS: Three LPs were identified. LP3 (high consumption of sweet and salty snacks, sugar sweetened soft drinks and juices, and high amount of screen time) was positively associated with diastolic BP (B, 0.52; 95% confidence interval = 0.05-0.99) and the existence of HTN (odds ratio = 1.12; 95% confidence interval = 1.00-1.25). Participants in the highest tertile of LP3 spent mean 3 h of screen time, consumed 1.5 portions of sweet and/or salty snacks and 1 L of soft drinks on a daily basis, were associated with 12% higher risk of HTN. CONCLUSIONS: Focusing on the combination of eating and lifestyle behaviours may more accurately identify, and therefore guide preventive measures tailored to the specific needs of high-risk populations.

The importance of protein intake in master marathon runners.

OBJECTIVES: The aim of this study was to investigate the relationships between protein intake (during the tapering period and the race), marathon performance, body composition, acute race-induced changes, and selected metabolic- and muscle damage-related blood biomarkers in recreational master runners. METHODS: In 58 experienced master runners (58.28 y ± 1.07 y, 174.06 cm ± 0.72 cm, 78.51 kg ± 0.76 kg body mass, 21.38% ± 0.52% body fat, mean ± SEM), nutritional intake was evaluated 1 wk before the race and during the marathon. Body composition was evaluated before and 2 h after the race. Blood samples were collected at the same time points. RESULTS: Body fat and lean body mass (LBM) were significantly reduced after the marathon (P < 0.01; η2: 0.311-0.888). Significant negative correlations were observed between energy intake from carbohydrates and proteins (expressed per LBM), marathon performance, and race-induced changes of blood metabolic-muscle damage indices (P < 0.05; r: -0.522 to -0.789). Positive correlations were observed between energy from carbohydrates and proteins per LBM, and body mass and LBM changes (P < 0.05; r: 0.485-0.814). The specific contribution of protein intakes per LBM (beta coefficient: -0.789 to 0.615) on race-induced changes of body composition and blood markers was the same as that of carbohydrate intakes per LBM (beta coefficient: -0.777 to 0.559). CONCLUSIONS: Marathon-induced changes in body composition and metabolic blood indices are highly related to protein intake, either during the tapering period or during the race, with runners experiencing the lowest changes when consuming higher protein intakes.

Combining urine color and void number to assess hydration in adults and children.

BACKGROUND/OBJECTIVES: To test the diagnostic ability of two combined practical markers for elevated urine osmolality (underhydration) in free-living adults and children. SUBJECTS/METHODS: One hundred and one healthy adults (females n = 52, 40 ± 14 y, 1.70 ± 0.95 m, 76.7 ± 17.4 kg, 26.5 ± 5.5 kg/m2) and 210 children (females = 105, 1.49 ± 0.13 m, 43.4 ± 12.6 kg, 19.2 ± 3.2 kg m-2) collected urine for 24-h. Urine was analyzed for urine osmolality (UOsm), color (UC), while the number of voids (void) was also recorded. Receiver Operating Characteristic (ROC) analysis was performed for UC, void, and combination of UC and void, to determine markers' diagnostic ability for detecting underhydration based on elevated UOsm (UOsm ≥ 800 mmol kg-1). RESULTS: Linear regression analysis revealed that UC was significantly associated with UOsm in both adults (R2 = 0.38; P < 0.001) and children (R2 = 0.45; P < 0.001). Void was significantly associated with UOsm in both adults (R2 = 0.13; P < 0.001) and children (R2 = 0.15; P < 0.001). In adults, when UC > 3 and void <7 were combined, the overall diagnostic ability for underhydration was 97% with sensitivity and specificity of 100% and 88%, respectively. In children, UC > 3 and void <5 had an overall diagnostic ability for underhydration of 89% with sensitivity and specificity of 100% and 62%, respectively. CONCLUSIONS: Urine color alone and the combination of urine color with void number can a valid and simple field-measure to detect underhydration based on elevated urine osmolality.

Students Living in the Islands are Heavier and have Lower Fitness Levels Compared to their Mainland Counterparts; Results from the National Action for Children's Health (EYZHN) Program.

Few studies have examined variations in obesity by geographic location in youth and its relation with fitness levels. The present study investigated the association between geographic status (islands versus mainland), excess of body weight and fitness levels among 335.810 schoolchildren (male: 51.3%, 6-18 y, during the school year 2014-2015). Students' anthropometric parameters and fitness levels - accessed via the Euro-fit test - were measured by trained physical education teachers and evaluated according to published norms. Prevalence of overweight (23.0 Vs 21.8%) and obese (10.1 Vs 8.0%) was significantly higher for students living in the islands contrary to their mainland counterparts. A significant difference was also observed for centrally obese children (33.5 Vs 28.2%). Except for speed test .408), in all other four fitness tests, the students from the islands presented significantly lower performance (≤25th percentile of published age- and sex-specific normative values) versus their mainland counterparts. Boys and girls living in the islands had 48% and 37% increased odds of low physical fitness (as a total), respectively, compared to their mainland counterparts. Likewise, children living in islands presented increased odds of being overweight or obese by 19% and 15% in boys and girls, respectively, as compared to those living in the mainland. Increased general and abdominal adiposity have a direct negative impact on students' performance in Physical Fitness tests. Our data highlight the problem of excessive body weight that children living in rural areas, face.

Rate of Force Development, Muscle Architecture, and Performance in Elite Weightlifters.

PURPOSE: The purpose of the present study was to investigate the relationship between weightlifting performance and the rate of force development (RFD), muscle architecture, and body composition in elite Olympic weightlifters. METHODS: Six male Olympic weightlifters (age 23.3 [3.4] y, body mass 88.7 [10.2] kg, body height 1.76 [0.07] m, snatch 146.7 [15.4] kg, clean and jerk 179.4 [22.1] kg), all members of the national team, participated in the study. Athletes completed a 16-week periodized training program aiming to maximize their performance at the national competition event. Measurements, including maximal strength (1-repetition maximum) in snatch, clean and jerk, back and front squat, isometric leg press RFD and peak force, countermovement jump, vastus lateralis muscle architecture, and body composition, were performed before and after the training period. RESULTS: Weightlifting performance increased significantly after training (P < .05). Leg press RFD increased only in time windows of 0 to 200 and 0 to 250 milliseconds after training (8.9% [8.5%] and 9.4% [7.7%], respectively, P < .05) while peak force remained unaltered (P < .05). Front squat strength increased significantly (P < .05), while countermovement jump power increased 2.3% (2.1%) (P < .05). No changes were observed for muscle architecture and lean body mass (P > .05). Significant correlations were observed between performance in snatch and clean and jerk with isometric leg press RFD, at all time windows, as well as with lean body mass and squat 1-repetition maximum. CONCLUSIONS: These results suggest that regular examination of RFD, lean body mass, and lower extremities' 1-repetition maximum may be useful performance predictors in elite Olympic weightlifters.

Exercise-Associated Hyponatremia during the Olympus Marathon Ultra-Endurance Trail Run.

Research on hyponatremia during mountain marathons is scarce. The present study aimed to investigate the prevalence of exercise-associated hyponatremia during a 44-km trail running race that reached an altitude of 2780 m (Olympus Marathon). Sixty-two runners (five women) who completed the race participated in the study (age: 34.4 ± 8.6 years; height: 1.77 ± 0.06 m; and weight: 75.3 ± 10.0 kg). Anthropometric characteristics, blood, and urine samples were collected pre- and post-race. Food and fluid intake were recorded at each checkpoint. Due to race regulations, the runners could not carry any additional food and fluids besides the ones provided at specific checkpoints. Five runners (8%) exhibited asymptomatic hyponatremia (serum sodium <135 mmol∙L-1). Serum sodium in the hyponatremic runners decreased from 138.4 ± 0.9 (pre) to 131.4 ± 5.0 mmol∙L-1 (post), p < 0.05. Plasma osmolality increased only in the eunatremic runners (pre: 290 ± 3; post: 295 ± 6 mmol∙kg-1; p < 0.05). Plasma volume decreased more in the hyponatremic compared to eunatremic runners (-4.4 ± 2.0 vs. -3.2 ± 1.4%, p < 0.05). Lastly, dietary sodium intake was lower in the hyponatremic runners compared to eunatremic (789 ± 813 vs. 906 ± 672 mg; p < 0.05). The incidence of hyponatremia among the athletes was relatively low, possibly due to race conditions.

Fiber Type Composition and Rate of Force Development in Endurance- and Resistance-Trained Individuals.

Methenitis, S, Spengos, K, Zaras, N, Stasinaki, A-N, Papadimas, G, Karampatsos, G, Arnaoutis, G, and Terzis, G. Fiber type composition and rate of force development in endurance- and resistance-trained individuals. J Strength Cond Res 33(9): 2388-2397, 2019-The purpose of the study was to investigate the relationship between muscle fiber composition and the rate of force development (RFD) in well-trained individuals with different training background. Thirty-eight young men with different training background participated: 9 endurance runners, 10 power-trained individuals, 9 strength-trained individuals, and 10 sedentary individuals. They performed maximal isometric leg press for the measurement of RFD. Body composition (dual x-ray absorptiometry) and vastus lateralis fiber type composition were also evaluated. When all participants were examined as a group, moderate correlations were found between the percent of type II muscle fibers and RFD between 100 and 600 milliseconds (r = 0.321-0.497; p ≤ 0.05). The correlation coefficients were higher for the cross-sectional area (CSA) and the %CSA of type II and IIx muscle fibers (r = 0.599-0.847; p < 0.001). For the power group, RFD up to 250 milliseconds highly correlated with % type IIx muscle fibers and type IIx fiber CSA (r = 0.670-0.826; p ≤ 0.05), as well as with %CSA of type IIx fibers (r = 0.714-0.975; p ≤ 0.05). Significant correlations were found between the relative RFD (·kg lower extremities lean mass) and CSA-%CSA of type II and IIx fibers for the power group (r = 0.676-0.903; p ≤ 0.05). No significant correlations were found between muscle morphology and RFD for the other groups. In conclusion, the present data suggest that there is a strong link between the type IIx muscle fibers and early RFD and relative RFD in power-trained participants. Type II fibers seem to be moderately linked with RFD in non-power-trained individuals.

Association of Anthropometric and Lifestyle Parameters with Fitness Levels in Greek Schoolchildren: Results from the EYZHN Program.

OBJECTIVE: The aim of the study was to evaluate physical fitness (PF) and identify its anthropometric and lifestyle determinants in a sample of Greek schoolchildren. METHODS: The study sample consisted of 335,810 schoolchildren (♂: 51.3%, 6-18 years old). Students' anthropometric parameters and PF levels-assessed via the Eurofit test battery-were measured by trained physical education teachers and evaluated according to the available norms, while their lifestyle habits were assessed through a questionnaire. RESULTS: In all applied PF tests, students' performance was negatively associated with the presence of obesity and central obesity, defined through international criteria for body mass index and waist to height ratio, respectively. According to multiple logistic regression analysis, the presence of overweight/obesity [odds ratio (OR): 4.43, 95% confidence interval (CI): 3.98-4.93], low adherence to the MD (KIDMED ≤ 3) (OR: 1.27, 95% CI: 1.09-1.48), and increased time spent in sedentary activities (>2 h per day) (OR: 1.16, 95% CI: 1.03-1.29) were positively associated with poor PF, after adjusting for age and sex. In contrast, for every 1 day increase in the weekly frequency of engagement in athletic activity, the probability of poor PF decreased by 26% (OR: 0.74, 95% CI: 0.72-0.77). In a similar model, the presence of central obesity emerged as an even stronger possible predictor of poor PF (OR: 5.20, 95% CI: 4.66-5.78), compared to the presence of general obesity. CONCLUSION: Higher general or abdominal adiposity, as well as the adoption of a low-quality diet and a sedentary lifestyle, is strongly associated with low PF levels during childhood.

The Importance of Lean Body Mass for the Rate of Force Development in Taekwondo Athletes and Track and Field Throwers.

The rate of force development (RFD) is vital for power athletes. Lean body mass (LBM) is considered to be an essential contributor to RFD, nevertheless high RFD may be achieved by athletes with either high or low LBM. The aim of the study was to describe the relationship between lower-body LBM and RFD, and to compare RFD in taekwondo athletes and track and field (T&F) throwers, the latter having higher LBM when compared to taekwondo athletes. Nine taekwondo athletes and nine T&F throwers were evaluated for countermovement jumping, isometric leg press and leg extension RFD, vastus lateralis (VL), and medial gastrocnemius muscle architecture and body composition. Lower body LBM was correlated with RFD 0-250 ms (r = 0.81, p = 0.016). Taekwondo athletes had lower LBM and jumping power per LBM. RFD was similar between groups at 30-50 ms, but higher for throwers at 80-250 ms. RFD adjusted for VL thickness was higher in taekwondo athletes at 30 ms, but higher in throwers at 200-250 ms. These results suggest that lower body LBM is correlated with RFD in power trained athletes. RFD adjusted for VL thickness might be more relevant to evaluate in power athletes with low LBM, while late RFD might be more relevant to evaluate in athletes with higher LBM.

Progressive Dehydration in Junior Laser Class Sailors During World Championship.

The purpose of this article is to assess the hydration status of elite young sailing athletes during World Championship competition. Twelve young, elite, male, Laser Class sailors (age: 15.8 ± 1.1 y, height: 1.74 ± 0.1 m, weight: 65.1 ± 1.5 kg, body fat: 12.5 ± 3.1%, training experience: 7.0 ± 1.2 y) participated in this descriptive study. After three-day baseline bodyweight measurements, hydration status was assessed via pre- and post-race body weights, urine-specific gravity, and thirst ratings via a visual analog scale during four consecutive days of racing. Measurements and data collection took place at the same time each racing day, with mean environmental temperature, humidity, and wind speed at 23.0 ± 0.8°C, 64-70%, and 9 ± 1 knots, respectively. Average racing time was 130 ± 9 min. Body weight was significantly decreased following each race-day as compared to prerace values (Day 1: -1.1 ± 0.2, Day 2: -2.5 ± 0.1, Day 3: -2.8 ± 0.1, and Day 4: -3.0 ± 0.1% of body weight; p < 0.05). The participants exhibited dehydration of -2.9 ± 0.2 and -5.8 ± 0.2% of body weight before and after the fourth racing day as compared to the three-day baseline body weight. Urine-specific gravity (pre-post → Day 1: 1.014-1.017; Day 2: 1.019-1.024; Day 3: 1.021-1.026; Day 4: 1.022-1.027) and thirst (pre-post → Day 1: 2.0-5.2; Day 2: 3.2-5.5; Day 3: 3.7-5.7; Day 4: 3.8-6.8) were also progressively and significantly elevated throughout the four days of competition. The data revealed progressive dehydration throughout four consecutive days of racing as indicated by decreased body weight, elevated urine concentration, and high thirst.

Fluid consumption pattern and hydration among 8-14 years-old children.

BACKGROUND/OBJECTIVES: Children consume various fluids to meet dietary water intake needs. However, the contribution of different fluid types on hydration is unclear. The purpose of this study was to develop fluid intake patterns and examine their association with hydration, as indicated by 24-h urine osmolality. SUBJECTS/METHODS: Two hundred ten (105 girls) healthy children (height: 1.49 ± 0.13 m, weight: 43.4 ± 12.6 kg, body fat: 25.2 ± 7.8%) recorded their fluid intake for two consecutive days, and collected their urine for 24-h during the 2nd day, while conducting their normal daily activities. Urine samples were analyzed for specific gravity and osmolality. Factor analysis with principal components method was applied to extract dietary patterns from six fluid groups. Linear regression analysis evaluated the associations between the extracted dietary patterns and hydration based on 24-h urine osmolality. RESULTS: The analysis revealed the following six components: 1, characterized by consumption of milk and fresh juice, but not packaged juice; 2, by regular soda and other drinks, but not water; 3, by fresh juice and other drinks; 4, by packaged juice, but not regular soda; 5, by water and milk; and 6, by fresh juice. Component 5 was negatively correlated with urine osmolality (P = 0.001) indicating better hydration, whereas component 2 was positively correlated with urine osmolality (P = 0.001). CONCLUSIONS: A drinking pattern based on water and milk was associated with better hydration, as indicated by lower urine osmolality, whereas drinking regular soda and other drinks but not water was associated with inferior hydration.

Coffee with High but Not Low Caffeine Content Augments Fluid and Electrolyte Excretion at Rest.

BACKGROUND: Low levels of caffeine ingestion do not induce dehydration at rest, while it is not clear if larger doses do have an acute diuretic effect. The aim of the present investigation was to examine the acute effect of low and high levels of caffeine, via coffee, on fluid balance in habitual coffee drinkers (at least one per day) at rest. METHODS: Ten healthy adults (eight males and two females; age: 27 ± 5 years, weight: 89.5 ± 14.8 kg, height: 1.75 ± 0.08 m, and body mass index: 29.1 ± 4.4 kg m-2) ingested 200 mL of water (W), coffee with low caffeine (3 mg kg-1, LCAF), or coffee with high caffeine (6 mg kg-1, HCAF) on three respective separate occasions. All sessions were performed at 09:00 in the morning in a counterbalanced, crossover manner, at least 5 days apart. Subjects remained in the laboratory while urine samples were collected every 60 min for 3 h post ingestion. RESULTS: Absolute caffeine consumption was 269 ± 45 and 537 ± 89 mg for the LCAF and HCAF, respectively. Coffee ingestion at the HCAF trial induced greater diuresis during the 3-h period (613 ± 101 mL, P < 0.05), when compared to W (356 ± 53 mL) and LCAF (316 ± 38 mL). In addition, cumulative urinary osmotic excretion was significantly greater in the HCAF (425 ± 92 mmol, P < 0.05), as compared to the W (249 ± 36 mmol) and LCAF (177 ± 16 mmol) trials. CONCLUSION: The data indicate that caffeine intake of 6 mg kg-1 in the form of coffee can induce an acute diuretic effect, while 3 mg kg-1 do not disturb fluid balance in healthy casual coffee drinking adults at rest.

The effect of hypohydration on endothelial function in young healthy adults.

PURPOSE: Hypohydration has been suggested as a predisposing factor for several pathologies including cardiovascular diseases (CVD). While CVD are the leading cause of death worldwide, no study has investigated whether acute hypohydration affects endothelial function and cardiovascular function. METHODS: Ten young, healthy males participated in this crossover study (age: 24.3 ± 2.3 year; weight: 80.8 ± 5.3 kg; BMI: 24.3 ± 0.4 kg m-2). Each subject completed two measurements of endothelial function by flow-mediated dilation (FMD) in euhydrated and hypohydrated state separated by 24 h. Following baseline assessment of hydration status and FMD, the subjects completed 100 min of low-intensity intermittent walking exercise to achieve hypohydration of -2 % of individual body mass. For the rest of the day, a standardized, low water content diet was provided. The following morning, hydration markers and endothelial function were recorded. RESULTS: Hypohydration by -1.9 ± 0.1 % of body mass resulted in decreased plasma volume by -3.5 ± 1.8 % and increased plasma osmolality by 9 ± 2 mmol kg-1 (P < 0.001). FMD as a response to hypohydration decreased by -26.8 ± 3.9 % (P < 0.05). CONCLUSION: The data suggested that a small degree of hypohydration induced by moderate exercise and fluid restriction significantly impaired endothelial function.

Validation of a urine color scale for assessment of urine osmolality in healthy children.

AIM: Urine color (UC) is a practical tool for hydration assessment. The technique has been validated in adults, but has not been tested in children. PURPOSE: The purpose of the study was to test the validity of the urine color scale in young, healthy boys and girls, as a marker of urine concentration, investigate its diagnostic ability of detecting hypohydration and examine the ability of children to self-assess UC. METHODS: A total of 210 children participated (age: 8-14 years, body mass: 43.4 ± 12.6 kg, height: 1.49 ± 0.13 m, body fat: 25.2 ± 7.8 %). Data collection included: two single urine samples (first morning and before lunch) and 24-h sampling. Hydration status was assessed via urine osmolality (UOsmo) and UC via the eight-point color scale. RESULTS: Mean UC was 3 ± 1 and UOsmo 686 ± 223 mmol kg(-1). UC displayed a positive relationship as a predictor of UOsmo (R (2): 0.45, P < 0.001). Based on the receiver operating curve, UC has good overall classification ability for the three samples (area under the curve 85-92 %), with good sensitivity (92-98 %) and specificity (55-68 %) for detecting hypohydration. The overall accuracy of the self-assessment of UC in the morning or the noon samples ranged from 67 to 78 %. Further threshold analysis indicated that the optimal self-assessed UC threshold for hypohydration was ≥4. CONCLUSIONS: The classical eight-point urine color scale is a valid method to assess hydration in children of age 8-14 years, either by researchers or self-assessment.

Maternal lifestyle characteristics during pregnancy, and the risk of obesity in the offspring: a study of 5,125 children.

BACKGROUND: To investigate the association between gestational weight gain, maternal age and lifestyle habits (e.g., physical activity, smoking, and alcohol consumption) during pregnancy, with Body Mass Index of the offspring at the age of 8. METHODS: Α random sample of 5,125 children was extracted from a national database and matched with their mothers. With the use of a standardised questionnaire, telephone interviews were carried out for the collection of information like: maternal age at pregnancy, gestational weight gain (GWG), exercise levels, smoking and alcohol consumption. The Body Mass Index (BMI) status of the offspring at the age of 8 was calculated from data retrieved from the national database (e.g., height and weight). RESULTS: The odds for being overweight/obese at the age of 8 for 1 kg GWG, for smoking, and for mild exercise during pregnancy compared to sedentary was 1.01 (95%CI: 1.00, 1.02), 1.23 (95%CI: 1.03, 1.47) and 0.77 (95%CI: 0.65, 0.91), respectively. Further analysis revealed that offspring of women who exceeded the Institute of Medicine (IOM) maternal weight gain recommendations were at an increased risk of obesity (OR: 1.45; 95%CI, 1.26, 1.67) compared with offspring of women with GWG within the recommended range. Maternal age and alcohol consumption were not associated with the outcome (p > 0.05). CONCLUSION: GWG, physical activity and smoking status during pregnancy were significantly associated with obesity for the offspring at the age of 8. Health care professionals should strongly advise women to not smoke and to perform moderate exercise during pregnancy to prevent obesity in the offspring in later life.

Fluid Balance During Training in Elite Young Athletes of Different Sports.

Although there are many studies demonstrating a high percentage of adult athletes who start exercise in suboptimal hydration state, limited data concerning hydration levels in athletic youth exist. The purpose of this study was to identify the hydration status of elite young athletes of different sports, during a typical day of training. Fifty-nine young elite male athletes from different sports (basketball, gymnastics, swimming, running, and canoeing) participated in the study (age: 15.2 ± 1.3 years; years of training: 7.7 ± 2.0). Hydration status was assessed in the morning, before and immediately after practice. Data collection took place at the same time of the day, with mean environmental temperature and humidity at the time of the measurements at 27.6 ± 0.9° C and 58 ± 8%, respectively. All athletes trained for approximately 90 minutes, and they were consuming fluids ad libitum throughout their practice. Over 89% of the athletes were hypohydrated (urine specific gravity [USG] ≥1.020 mg·dl) based on their first morning urine sample. Pretraining urine samples revealed that 76.3% of the athletes were hypohydrated, whereas a significant high percent remained hypohydrated even after training according to USG values ≥1.020 mg·dl (74.5%) and urine color scale: 5-6 (76.3%). Mean body weight loss during training was -1.1 ± 0.07%. We concluded that the prevalence of hypohydration among elite young athletes is very high, as indicated by the USG and urine color values. The majority of the athletes was hypohydrated throughout the day and dehydrated even more during practice despite fluid availability.

Mild dehydration and cycling performance during 5-kilometer hill climbing.

CONTEXT: Hydration has been shown to be an important factor in performance; however, the effects of mild dehydration during intense cycling are not clear. OBJECTIVE: To determine the influence of mild dehydration on cycling performance during an outdoor climbing trial in the heat (ambient temperature = 29.0°C ± 2.2°C). DESIGN: Crossover study. SETTING: Outdoor. PATIENTS OR OTHER PARTICIPANTS: Ten well-trained, male endurance cyclists (age = 28 ± 5 years, height = 182 ± 0.4 cm, mass = 73 ± 4 kg, maximal oxygen uptake = 56 ± 9 mL·min(-1)·kg(-1), body fat = 23% ± 2%, maximal power = 354 ± 48 W). INTERVENTION(S): Participants completed 1 hour of steady-state cycling with or without drinking to achieve the desired pre-exercise hydration level before 5-km hill-climbing cycling. Participants started the 5-km ride either euhydrated (EUH) or dehydrated by -1% of body mass (DEH). MAIN OUTCOME MEASURE(S): Performance time, core temperature, sweat rate, sweat sensitivity, and rating of perceived exertion (RPE). RESULTS: Participants completed the 5-km ride 5.8% faster in the EUH (16.6 ± 2.3 minutes) than DEH (17.6 ± 2.9 minutes) trial (t1 = 10.221, P = .001). Postexercise body mass was -1.4% ± 0.3% for the EUH trial and -2.2% ± 0.2% for the DEH trial (t1 = 191.384, P < .001). Core temperature after the climb was greater during the DEH (39.2°C ± 0.3°C) than EUH (38.8°C ± 0.2°C) trial (t1 = 8.04, P = .005). Sweat rate was lower during the DEH (0.44 ± 0.16 mg·m(-2)·s(-1)) than EUH (0.51 ± 0.16 mg·m(-2)·s(-1)) trial (t8 = 2.703, P = .03). Sweat sensitivity was lower during the DEH (72.6 ± 32 g·°C(-1)·min(-1)) than EUH (102.6 ± 54.2 g·°C(-1)·min(-1)) trial (t8 = 3.072, P = .02). Lastly, RPE after the exercise performance test was higher for the DEH (19.0 ± 1.0) than EUH (17.0 ± 1.0) participants (t9 = -3.36, P = .008). CONCLUSIONS: We found mild dehydration decreased cycling performance during a 5-km outdoor hill course, probably due to greater heat strain and greater perceived intensity.

Endurance, explosive power, and muscle strength in relation to body mass index and physical fitness in greek children aged 7-10 years.

We aimed to model endurance, explosive power, and muscle strength in relation to body mass index (BMI) and physical-fitness tests in Greek children aged 7-10 years old. In the present large epidemiological study, anthropometric measurements and physical-fitness tests (i.e., multistage shuttle run, vertical jump, standing long jump, small ball throw and 30-m sprint) from 141,169 children were analyzed. Age- and sex-specific normative values for physical fitness tests were expressed as tabulated percentiles using the LMS statistical method. The correlation coefficients between BMI and performances were negative and significant for both sexes (p < .01) in all physical-fitness tests. The only exception was a positive correlation between ball throw and BMI (p < .01). Only 2.9% and 4.0% of boys and girls respectively, passed the upper quartiles in all tests. The performance in speed may serve as a predictive factor explaining, at least in part, the performance in aerobic endurance and explosive power in children aged 7-10 years. The presented population-based data for physical-fitness tests revealed that only a small percentage of these children are in the upper quartiles in all tests. Furthermore, the data suggests that speed performance can be used to predict physical fitness.