Validity of detrended fluctuation analysis of heart rate variability to determine intensity thresholds in elite cyclists.

Background: The evaluation of performance in endurance athletes and the subsequent individualisation of training is based on the determination of individual physiological thresholds during incremental tests. Gas exchange or blood lactate analysis are usually implemented for this purpose, but these methodologies are expensive and invasive. The short-term scaling exponent alpha 1 of detrended Fluctuation Analysis (DFA-α1) of the Heart Rate Variability (HRV) has been proposed as a non-invasive methodology to detect intensity thresholds. Purpose: The aim of this study is to analyse the validity of DFA-α1 HRV analysis to determine the individual training thresholds in elite cyclists and to compare them against the lactate thresholds. Methodology: 38 male elite cyclists performed a graded exercise test to determine their individual thresholds. HRV and blood lactate were monitored during the test. The first (LT1 and DFA-α1-0.75, for lactate and HRV, respectively) and second (LT2 and DFA-α1-0.5, for lactate and HRV, respectively) training intensity thresholds were calculated. Then, these points were matched to their respective power output (PO) and heart rate (HR). Results: There were no significant differences (p > 0.05) between the DFA-α1-0.75 and LT1 with significant positive correlations in PO (r = 0.85) and HR (r = 0.66). The DFA-α1-0.5 was different against LT2 in PO (p = 0.04) and HR (p = 0.02), but it showed significant positive correlation in PO (r = 0.93) and HR (r = 0.71). Conclusions: The DFA1-a-0.75 can be used to estimate LT1 non-invasively in elite cyclists. Further research should explore the validity of DFA-α1-0.5.HighlightsThe power and heart rate values derived from the DFA-α1-0.75 threshold showed high levels of validity and agreement when they were compared against the first lactate threshold.The second lactate threshold and the DFA-α1-0.5 were different (p < 0.05) but showed high levels of correlation.The detrended fluctuation analysis is a valid method to estimate the first lactate threshold and more studies are needed to verify its validity with the second lactate threshold.

Nutritional Habits of Professional Cyclists during Pre-Season.

The first aim of the present study was to assess the dietary intake of professional cyclists during pre-season. The second aim was to assess the dietary habits of this population during a complete season. Fifteen elite male (age: 23.2 ± 5.4 years) and twenty-three elite female (age: 20.1 ± 7.0 years) cyclists volunteered to participate in the study. Dietary nutrient intake during pre-season was assessed using a 72 h dietary recall interview, and a 136-item food frequency questionnaire was used to assess dietary habits during the year. Protein intake exceeded the PRI's recommendation of 0.83 g/kg/day for all cycling groups. Fat exceeded RI recommendations in females in both road (43.3%) and CXO (39.8%) cycling groups, whilst males were found to follow recommendations for fat intake. CHO intake was below recommendations in all groups. Intake of all vitamins exceeded recommendations, with the exception of B9 in female road cyclists (77.8% RDA) and vitamin D in all groups. With regards to mineral intake, consumption exceeded RDA/AI recommendations in all groups except for iodine in male XCO cyclists (61.6%), female road cyclists (61.6%), and female XCO cyclists (58%) and potassium in female road cyclists (74.6%). Males consumed greater amounts of eggs and non-processed foods than females. Road cyclists consumed greater amounts of fish and seafood and had a lower intake of coffee and tea than XCO cyclists. Better knowledge of food guidelines in terms of serving and food variety is important for professional cyclists at may impact health and performance.

Anthropometric differences between world-class professional track cyclists based on specialty (endurance vs. sprint).

BACKGROUND: Despite previous research suggesting that certain anthropometric characteristics are required to successfully perform in track cycling, current literature fails to describe these characteristics in depth in large cohorts of professional UCI cyclists. The main aims of the present study were to determine the anthropometric characteristics, body composition and somatotype of world-class professional track cyclists (male and female). METHODS: Anthropometric measurements were conducted of the body composition of ninety-eight world-class professional track cyclists in line with the International Society for Advancement of Kinanthropometry protocol. RESULTS: Male sprinters had a significantly larger body mass (85.9±8.3 vs. 74.0±6.5; P<0.001), muscle mass (44.1.9±4.4 vs. 35.3±2.5; P<0.001), body fat percentage (regardless of the formula used) and BMI (26.1±1.5 vs. 22.4±1.2; P<0.001) than endurance male cyclists. Furthermore, in females, sprinters had a higher BMI than endurance cyclists (23.4±2 vs. 1.4±1.6; P<0.01), with no differences in total body mass or body fat (P>0.05). None of the studied anthropometric parameters were found to differ between finalists and non-finalists, with the exception of femur breadth, upper arm girth, thigh girth and thigh skinfold. CONCLUSIONS: Intra-sport differences exist in the anthropometric characteristics of world-class professional track cyclists depending on their discipline (sprinter vs. endurance). Male sprinters showed a greater BMI, muscle mass and limb girth, and lower fat percentage than endurance cyclists. Female sprinters also showed a higher BMI than endurance cyclists, although no differences were seen in fat percentage or muscle mass.

Determination of Second Lactate Threshold Using Near-infrared Spectroscopy in Elite Cyclists.

The use of near-infrared spectroscopy could be an interesting alternative to other invasive or expensive methods to estimate the second lactate threshold. Our objective was to compare the intensities of the muscle oxygen saturation breakpoint obtained with the Humon Hex and the second lactate threshold in elite cyclists. Ninety cyclists performed a maximal graded exercise test. Blood capillary lactate was obtained at the end of steps and muscle oxygenation was continuously monitored. There were no differences (p>0.05) between muscle oxygen oxygenation breakpoint and second lactate threshold neither in power nor in heart rate, nor when these values were relativized as a percentage of maximal aerobic power or maximum heart rate. There were also no differences when men and women were studied separately. Both methods showed a highly correlation in power (r=0.914), percentage of maximal aerobic power (r=0.752), heart rate (r=0.955), and percentage of maximum heart rate (r=0.903). Bland-Altman resulted in a mean difference of 0.05±0.27 W·kg-1, 0.91±4.93%, 0.63±3.25 bpm, and 0.32±1.69% for power, percentage of maximal aerobic power, heart rate and percentage of maximum heart rate respectively. These findings suggest that Humon may be a non-invasive and low-cost alternative to estimate the second lactate threshold intensity in elite cyclists.

Anthropometric Characteristics, Body Composition and Somatotype of Elite Male Young Runners.

The purpose of the present study was to describe the anthropometric characteristics, body composition and somatotype of elite male young runners (EYR), and to compare these variables according to the specialty in which they engaged (middle-distance vs. long-distance). This will enable an anthropometric profile chart to be established for them. Ninety EYR aged 17 to 23 years (18.4 ± 2.0) participated in the study. Athletes were divided into two groups according to the event in which they participated: middle-distance runners (MDR, n = 56) and long-distance runners (LDR, n = 34). Sixteen anthropometric variables were recorded for each participant: Weight, height, eight skinfolds, four girths, and two breadths. Body mass index (BMI), body composition and somatotype were calculated. Comparing MDR with the group of LDR, significant differences were found to exist for height, weight, relaxed upper arm girth, flexed and tensed upper arm girth, total upper arm area, upper arm muscle area, and thigh muscle area. No significant differences were observed in the other variables. MDR are taller, heavier and have larger girths than LDR. Coaches and sports scientists can use the data obtained to better control training, as well as for talent identification and athlete selection.

Anthropometric and Physical Fitness Profiles of World-Class Male Padel Players.

The aims of this study were to describe and compare the anthropometric and physical fitness attributes of male padel players according to their competitive level, and to establish a functional anthropometric and physical profile. A total of 60 males participated in the present study. Athletes were grouped according to competition level, forming an elite group (n = 25) and a subelite group (n = 35). Anthropometric variables, hand grip and lumbar isometric strength, flexibility, and lower-body muscular strength were measured. Elite padel players were significantly older and showed significantly lower values for the thigh and calf skinfolds, the sum of six and eight skinfolds, and the sum of lower-limb skinfolds than the subelite group. Elite padel players also had significantly lower values than subelite players for body fat percentage and thigh fat area, whilst showing significantly higher values for lumbar isometric strength. Somatotype of the elite padel players could be defined as endo-mesomorphic. Results suggest that training and talent identification of padel players should focus on their anthropometric characteristics and physical fitness, with these being different between elite and subelite athletes. Normative data could help coaches throughout the talent identification process and in the design of training programs when seeking to optimise sports performance.

Nutritional intake and body composition changes in a UCI World Tour cycling team during the Tour of Spain.

The aim of this study was to quantify the food intake of an International Cyclist Union (UCI) World Tour professional cyclist team and to analyse changes in body composition during the Tour of Spain. Nine male professional road cyclists (31.3 ± 3.0 years) volunteered to participate in the study. Nutritional data were collected each day throughout the 3-week Tour by two trained investigators who weighed the food ingested by the cyclists. Mean nutritional intake of the cyclists was as follows: carbohydrate, 12.5 ± 1.8 g/kg/day of body weight (BW) (65.0 ± 5.9%); fat, 1.5 ± 0.5 g/kg/day BW (17.9 ± 5.6%); and protein, 3.3 ± 0.3 g/kg/day BW (17.1 ± 1.6%). Intake of all micronutrients, except for folate, vitamin D and potassium (which were 78.7%, 46% and 84% of Recommended Dietary Allowances (RDA), respectively), exceeded the RDA. Height, weight, skinfolds, circumferences and diameters were taken following the guidelines outlined by the International Society for the Advancement of Kinanthropometry. Body density, body fat percentage, muscle mass, total muscle mass and fat mass of the arms and thighs were calculated. Percentage body fat, fat mass and upper arm fat mass significantly decreased (p < .05) after the Tour independent of the equation method used in the calculations. Total muscle mass remained unchanged. Generally, this sample of cyclists consumed more protein and less fat than the recommended amount and had low weight, BMI and fat mass. It is suggested that sports nutritionists design personalised diets in order to maintain a correct proportion of nutrients as well as controlling possible anthropometrical changes that could affect performance.

Effect of induced alkalosis on performance during a field-simulated BMX cycling competition.

OBJECTIVES: The aim of the present study was to test the effect of sodium bicarbonate (NaHCO3-) ingestion on performance during a simulated competition on a Bicycle Motocross (BMX) track. DESIGN: Double-blind cross-over study. METHODS: Twelve elite male BMX cyclists (age: 19.2±3.4 years; height: 174.2±5.3cm; body mass: 72.4±8.4kg) ingested either NaHCO3- (0.3g.kg-1 body weight) or placebo 90min prior to exercise. The cyclists completed three races in a BMX Olympic track interspersed with 15min of recovery. Blood samples were collected to assess the blood acid-base status. Performance, cardiorespiratory, heart rate variability (HRV) as well as subjective variables were assessed. RESULTS: The main effect of condition (NaHCO3- vs. placebo) was observed in pH, bicarbonate concentration and base excess (p<0.05), with a significant blood alkalosis. No changes were found in time, peak velocity and time to peak velocity for condition (p>0.05). The HRV analysis showed a significant effect of NaHCO3- ingestion, expressed by the rMSSD30 (root mean square of the successive differences) (p<0.001). There was no effect of condition on oxygen uptake, carbon dioxide production, or pulmonary ventilation (p>0.05). Finally, there was no effect of condition for any subjective scale (p>0.05). CONCLUSIONS: We present here the first field condition study to investigate the effect of bicarbonate ingestion over performance in BMX discipline. The results showed that NaHCO3--induced alkalosis did not improve performance in a simulated BMX competition in elite BMX cyclists, although future studies should consider the effects of NaHCO3- on autonomic function as a component of recovery.

World and Olympic mountain bike champions' anthropometry, body composition and somatotype.

BACKGROUND: The aim of the study was to describe the anthropometric profile of male Olympic cross country (XCO) mountain bikers. METHODS: Fifty one XCO bikers participated in this study, divided into an elite group who competed in top level international competitions, and a non-elite group who competed at a national level. The elite group was further classified according to whether they had been world or Olympic champion mountain bikers (WOC) or not (NWOC). The anthropometric profiles included the measurements of height, weight, arm span, skinfolds, girths, and breadths. Body Mass Index (BMI), body composition and somatotype were also calculated. Variables was described as mean, standard deviation and range. The standardizing of the variables was carried out using the Shapiro-Wilk with Lillieforts correction and homoscedasticity was analyzed using the Levene Test. After verifying that the variables were normal, the data were analyzed using non-paired t-tests (elite vs. non-elite and WOC vs. NWOC). RESULTS: Elite riders had significantly lower BMI, lower percentage of fat, total thigh area and larger thigh muscle area than the sub-elite riders, and presented significantly lower values for the endomorphic component and higher values for the ectomorphic component. The mean somatotype of the elite riders could be defined as ecto-mesomorphic (1.7-4.6-3.1). CONCLUSIONS: Comparisons between of WOC riders and NWOC, showed that the WOC bikers had a significantly higher value for weight, arm span, upper arm girth relaxed and upper arm girth flexed and tensed, calf girth, total upper arm area, and upper arm muscle area than the NWOC riders group.

Efecto de un programa de intervención sobre el estrés percibido, autoestima y rendimiento en jóvenes pilotos de motociclismo de elite / Effect of an intervention program on perceived stress, self-esteem and performance in young elite motorcyclists

En la especialidad deportiva de motociclismo la literatura científica se ha centrado en aspectos tecnológicos, de seguridad, incluso patrones de lesiones, existiendo poca información sobre variables psicológicas de los deportistas. El objetivo de nuestro estudio fue evaluar si el efecto de una intervención en habilidades técnicas y condición física sobre la percepción de estrés, autoestima, la autovaloración, la valoración de otros, y finalmente la ejecución. La muestra estuvo compuesto por 27 pilotos jóvenes de élite, participantes del Red Bull Moto GP Rookies Cup, de los cuales 16 sujetos realizaron un programa de intervención (Grupo Experimental, GE), mientras que el resto fue el Grupo Control (GC), se recogieron diversas variables en la primera y la última carrera de la temporada. Nuestros resultados indican que el GE mantuvo controlado el nivel de estrés, una mejor técnica, condición física y psicológica y además obtuvo mejores resultados en las competiciones, en comparación con el GC. Por tanto, concluimos que el programa de intervención ha sido eficaz para mantener los niveles de estrés, mejorar sus habilidades técnicas, tácticas y psicológicas, y además para mejorar la ejecución a lo largo de la temporada deportiva (AU)

In the motorcycling sport specialty, scientific literature has focused on technology, safety or even on injury variables; however there is little information regarding psychological variables. The aim of our study was to evaluate the effect of a technical and physical intervention on psychological variables such as self-esteem, self-assessment, appraisal of others and, finally, performance. The sample was made up of twenty-seven young elite road-race motorcyclists who competed in the Red Bull Moto GP Rookies Cup. 16 of whom completed an intervention program (Experimental Group, EG), while the other 14 belonged to the Control Group (CG). We collected the measurements in the first and last race of the season. Our results indicate the EG had controlled the stress level, had a better technique, physical, and psychological conditions, besides better competition performance, in comparison with the CG. We conclude that our intervention program has been effective at maintaining stress levels, bettering technical, tactical and psychological skills, and also improving performance throughout the competition period (AU)

La actividad física en adolescentes no muestra relación con el consumo máximo de oxígeno / Physical activity is not associated with maximum consumption of oxygen in adolescents

Introducción y objetivos: La capacidad aeróbica es un potente factor de riesgo cardiovascular e indicador de salud. La actividad física es también reconocida como un importante componente del estilo de vida saludable. Sin embargo, la relación entre capacidad aeróbica y actividad física no está muy clara en adolescentes. Por ello, el objetivo del presente estudio fue examinar la asociación entre el VO2max como medida objetiva de la capacidad aeróbica y la actividad física, medida con el International Physical Activity Questionnaire (IPAQ), en adolescentes. Método: En el estudio participaron un total de 155 adolescentes (79 chicos y 76 chicas) de 15-18 años de edad. El VO2max fue medido de manera directa a través de un analizador de gases portátil (K4b2, Cosmed) durante la realización del 20 Meter Shuttle Run test. El grado de actividad física y el gasto energético se estimaron mediante el IPAQ en su versión corta autoadministrada. Resultados: Los chicos mostraron una mayor capacidad aeróbica y nivel de actividad física con respecto a las chicas (p≤0.001). No se encontraron relaciones significativas entre el gasto energético estimado (MET) y las variables de capacidad aeróbica, tanto en chicos como en chicas. Conclusiones: El nivel de actividad física medido a través del IPAQ no se relaciona consistentemente con la capacidad aeróbica (VO2max), por lo que recomendamos la utilización de otros métodos de medida más objetivos, fiables y factibles de ser utilizados en el ámbito educativo y sanitario. En base a los resultados que muestran una baja capacidad aeróbica de los adolescentes estudiados, coincidimos con la tendencia actual de demandar el desarrollo de programas específicos para mejorar la capacidad aeróbica de la población, con objeto de prevenir enfermedades cardiovasculares en la edad adulta (AU)

Introduction and objectives: Aerobic capacity is a potent factor of cardiovascular risk and health index. Physical activity is recognized also as an important component of healthy wayof life. Nevertheless, the relation between aerobic capacity and physical activity is not very clear in adolescents. The main purpose of this study was to examine the relationship between VO2max, as objective measure of the aerobic capacity, and the physical activity measured by means of the International Physical Activity Questionnaire (IPAQ), in adolescents. Method: A total of 155 adolescents of 15-18 years-old (79 boys and 76 girls) participated in the study. VO2max was objectively assessed using a portable gas analyzer (K4b2, Cosmed) during the 20 m Shuttle Run Test. Physical activity level and energy expenditure were estimated using the short IPAQ form. Results: Boys showed significantly bigger aerobic capacity and physical activity level than girls (p≤0.001). No relationships were found between energy expenditure measured by the IPAQ and variables of aerobic capacity in any gender. Conclusions: Physical activity level assessment by means of IPAQ (short auto-administered version) is not very reliable as predictive factor of aerobic capacity (VO2max) in adolescents. Therefore it is recommended to use other more objective measure methods, reliable and feasible that can be used in the educational and sanitary area. Finally, on the basis of the results that show a low aerobic capacity of the studied adolescents, we coincide with the current trend of demanding the development of specific programs to improve the aerobic capacity of the population, in order to prevent cardiovascular diseases in adult age (AU)

Physiological Responses to On-Court vs Running Interval Training in Competitive Tennis Players.

The aim of this study was to compare heart rate (HR), blood lactate (LA) and rate of perceived exertion (RPE) responses to a tennis-specific interval training (i.e., on-court) session with that of a matched-on-time running interval training (i.e., off-court). Eight well-trained, male (n = 4) and female (n = 4) tennis players (mean ± SD; age: 16.4 ± 1.8 years) underwent an incremental test where peak treadmill speed, maximum HR (HRmax) and maximum oxygen uptake (VO2max) were determined. The two interval training protocols (i.e., off- court and on-court) consisted of 4 sets of 120 s of work, interspersed with 90 s rest. Percentage of HRmax (95.9 ± 2.4 vs. 96.1 ± 2.2%; p = 0.79), LA (6.9 ± 2.5 vs. 6.2 ± 2.4 mmol·L(-1); p = 0.14) and RPE (16.7 ± 2.1 vs. 16.3 ± 1.8; p = 0.50) responses were similar for off-court and on-court, respectively. The two interval training protocols used in the present study have equivalent physiological responses. Longitudinal studies are still warranted but tennis-specific interval training sessions could represent a time-efficient alternative to off-court (running) interval training for the optimization of the specific cardiorespiratory fitness in tennis players. Key pointsOn-court interval training protocol can be used as an alternative to running interval trainingTechnical/tactical training should be performed under conditions that replicate the physical and technical demands of a competitive matchDuring the competitive season tennis on-court training might be preferred to off-court training.

Antioxidant defence and inflammatory response in professional road cyclists during a 4-day competition.

Cycling competitions represent an important physical overload even for well-trained individuals. In six professional cyclists, we studied the adaptive oxidative and anti-inflammatory response to a 4-day road cycling competition and its relationship with melatonin, an antioxidant and anti-inflammatory stress hormone. Blood and urine samples were collected before and after the competition. Plasma lipid peroxidation, cytokines (interleukin-1beta, interleukin-6, and tumour necrosis factor-alpha), creatine kinase and other metabolic markers, melatonin, erythrocyte glutathione, and glutathione peroxidase and reductase activities were measured. Urinary excretion of 6-sulphatoxymelatonin was analysed. Lipid peroxidation increased after the competition, but the erythrocyte glutathione pool remained unchanged. Changes in both glutathione peroxidase and reductase activities probably account for the recycling of glutathione after exercise. Interleukin-6 (216%) and tumour necrosis factor-alpha (159%) but not interleukin-1beta increased after exercise. A parallel increase in plasma melatonin concentrations was detected, whereas metabolic markers, including creatine kinase, showed minor modifications. Thus, professional cyclists display an adaptative response to the physical overloads in the competitions for which they are trained. Consequently, they seem to be able to regulate efficiently the intracellular oxidative stress, and prevent an exaggerated pro-inflammatory cytokines induction. A modulator role of melatonin in these adaptive responses is also supported.

A comparison of the activity profile and physiological demands between advanced and recreational veteran tennis players.

The aim of the study was to examine whether differences in playing level influence the activity profile and physiological demands of advanced and recreational veteran men's tennis players during an hour of tennis match play. Ten advanced (International Tennis Number [ITN] 3-5, 45.3 +/- 5.1 years) and 10 recreational (ITN 7-9, 44.8 +/- 4.7 years) veteran men's tennis players participated in 4 experimental sessions: (1) an ITN on-court assessment, (2) a laboratory incremental treadmill test, (3) an hour of simulated tennis match play, and (4) 30 minutes of tennis match play using a portable gas analyzer. Subjects' VO2 and heart rate (HR) were recorded by portable analyzers. Moreover, energy expenditure was evaluated by indirect calorimetry. Temporal structure and distance covered were determined from video recordings. Subjects' VO2 (24.5 +/- 4.1 vs. 23.3 +/- 3 ml x kg x min), HR (148.3 +/- 11.5 vs. 149.8 +/- 8.4 bpm), duration of rallies (DR) (6.3 +/- 4.1 vs. 7.6 +/- 5.5 seconds), and effective playing time (EPT) (21.7 +/- 5.0 vs. 23.6 +/- 5.4%), HR (148.3 +/- 11.5 vs. 149.8 +/- 8.4 bpm), and energy expenditure (263.1 +/- 49.4 and 281.3 +/- 61.8 kcal x min) during play did not differ significantly (p > 0.05) between advanced and recreational players. The advanced players covered significantly more meters than the recreational players during their 1-hour tennis matches (mean +/- SD: 3568.8 +/- 532.2 vs. 3173.8 +/- 226 m, p < 0.01) at lower running speeds. The results indicate that, independently of ability, tennis match play satisfies the American College of Sports Medicine recommendations for quantity and quality of exercise for the development and maintenance of cardiovascular fitness in healthy adults and seems to be a viable and highly popular mode of healthy activity.

Effects of the administration of feedback on performance of the bmx cycling gate start.

The aim of the present study was to determine the effect of the administration of external feedback (FB) on the time used to execute the gate start skill in BMX cycling discipline. The sample used was n = 6 riders from the Spanish national team (19.3 ± 2.1 years). An intragroup experimental design with repeated measures was used to compare the evolution of the skill developed by the participants before and after treatment, as well as the degree of retention of the possible learning. The results showed that there were no significant differences between the 2 first pre-test sessions (PRE), nor between any of the other treatment, post-test or re-test sessions (TREAT, POS and RET, respectively). Nevertheless, significant differences were observed between either of the PRE sessions and any of the TREAT, POS or RET sessions (p ≤ 0.028), showing a significant reduction of the time needed to perform this skill after TREAT (1.264 ± 0.045 ms in PRE, 1.047 ± 0.019 ms in POS, and 1.041 ± 0.021 ms in RET). In conclusion, the use of audiovisual FB and cognitive training of the skill can result in a significant improvement in the execution of the gate start in BMX reducing the time to develop the task. Key pointsThis work provides a practical application of many studies developed around teaching-learning technique in sport. In those studies this kind of applications were suggested as necessary.All the recent theories are applied in the real sport context, and using elite athletes.A successful program is proposed to be used by coaches and athletes just following a few simple guidelines, and this can be a really useful tool to follow.

Effects of sodium bicarbonate ingestion on performance and perceptual responses in a laboratory-simulated BMX cycling qualification series.

The objective of this study was to examine the effect of sodium bicarbonate (NaHCO3-) ingestion on performance and perceptual responses in a laboratory-simulated bicycle motocross (BMX) qualification series. Nine elite BMX riders volunteered to participate in this study. After familiarization, subjects undertook two trials involving repeated sprints (3 x Wingate tests [WTs] separated by 30 minutes of recovery; WT1, WT2, WT3). Ninety minutes before each trial, subjects ingested either NaHCO3- or placebo in a counterbalanced, randomly assigned, double-blind manner. Each trial was separated by 4 days. Performance variables of peak power, mean power, time to peak power, and fatigue index were calculated for each sprint. Ratings of perceived exertion were obtained after each sprint, and ratings of perceived readiness were obtained before each sprint. No significant differences were observed in performance variables between successive sprints or between trials. For the NaHCO3- trial, peak blood lactate during recovery was greater after WT2 (p < 0.05) and tended to be greater after WT3 (p = 0.07), and ratings of perceived exertion were not influenced. However, improved ratings of perceived readiness were observed before WT2 and WT3 (p < 0.05). In conclusion, NaHCO3- ingestion had no effect on performance and RPE during a series of three WT simulating a BMX qualification series, possibly because of the short duration of each effort and the long recovery time used between the three WTs. On the contrary, NaHCO3- ingestion improved perceived readiness before each WT.

Anthropometric characteristics, body composition and somatotype of elite junior tennis players.

OBJECTIVES: The aims of this study were to describe the anthropometric characteristics, body composition and somatotype of elite male and female junior tennis players, to compare the anthropometric data, body composition and somatotype of the first 12 elite junior tennis players on the ranking with the lower ranked players, and to establish an anthropometric profile chart for elite junior tennis players. METHODS: A total of 123 (57 males and 66 females) elite junior tennis players participated in this study. The athletes were divided into two groups, the first 12 and the lower ranked players, according to gender. A total of 17 anthropometric variables were recorded of each subject. RESULTS: There were no significant differences in height and weight between the first 12 and the lower ranked boys, while the first 12 girls were significantly taller than the lower ranked girls (p = 0.009). Significant differences were found for humeral and femoral breadths between the first 12 and the lower ranked girls (p = 0.000; p = 0.004, respectively). The mean (SD) somatotype of elite male junior tennis players could be defined as ectomesomorphic (2.4 (0.7), 5.2 (0.8), 2.9 (0.7)) and the mean (SD) somatotype of elite female junior tennis players evaluated could be defined as endomesomorphic (3.8 (0.9), 4.6 (1.0), 2.4 (1.0)). No significant differences were found in somatotype components between the first 12 and the lower ranked players of both genders. CONCLUSIONS: When comparing the first 12 and the lower ranked elite junior tennis players of both genders, no significant differences were observed in any measured item for the boys. By contrast, significant differences were observed in height and humeral and femoral breadths between the first 12 and the lower ranked girls, whereby the first 12 were taller and had wider humeral and femoral breadths than the lower ranked players. These differences could influence the playing style of junior female players.