As players in high performance youth soccer (HYPS) environments undergo large changes in growth and maturation throughout the course of their development, they require specific nutritional intakes if they are to meet these demands. The purpose of this review was to synthesise current nutritional research conducted within HYPS players.
A systematic approach, following PRISMA guidelines, was employed to capture all articles related to nutrition within HPYS using the databases MEDLINE and SPORTDiscus. Study quality and risk of bias were assessed using a Downs and Black instrument. Observational and intervention studies which investigated an element of nutritional status, knowledge, or intervention in academy aged players (U9 to U23s) within HPYS settings were included.
Fifty-three articles qualified assessing: current nutritional intake and energy balance (n = 21); ergogenic aids/supplements (n = 13); hydration status (n = 6); the influence of Ramadan fasting (n = 4); Vitamin D status (n = 4); female HPYS players (n = 3); nutrition knowledge (n = 2). Outcomes demonstrate a large proportion of HPYS players exhibit insufficient energy and carbohydrate intake, and a lack sufficient periodisation of nutrition to account for varying training/match loads. Large variability in energy intake and expenditure exists between and within chronological age groups, indicating the potential impact on growth and maturation. Female HPYS data is lacking but indicates similar trends to male counterparts.
HYPS players do not currently meet their energy requirements however the impact of growth and maturation is not fully understood. Furthermore, within this demographic future research is required into the barriers and enablers of players achieving adequate energy intake.
Plyometric training has shown to improve vertical jump height, but the design and implementation of a plyometric training programme for adolescents requires consideration of several variables as well as the time of the season. The purpose of this study was to implement a pragmatic programme that improves vertical jump height, and to monitor the effects of a 15 week off-season plyometric and resistance training programme on the vertical jump height in adolescent female volleyball players. Ten adolescent female volleyball players (age: 15.1 ± 0.9 years, height: 1.71 ± 0.04 m, body mass: 63.6 ± 6.0 kg, volleyball training experience: 5.1 ± 1.4 years) underwent 15 weeks of plyometric and resistance training (twice and once a week, respectively). A single-targeted block periodised approach and a linear periodisation model were applied. Vertical jump height was assessed before the programme (T1), after 4 weeks (T2), after 12 weeks (T3) and at the end of the programme (T4). Jump height significantly increased by 8.8% over the full time of the investigation. No significant difference was found between T1 and T2 but for all other pairwise comparisons. Similarly, leg power was observed to increase by 6.5% (P = 0.001). The 15-weeks training programme showed to improve jump height and leg power. In consideration of its practical nature and its results in comparison with similar intervention studies, the programme suggests practical relevance for coaches.
Tracking competition jump data provides a practical approach for assessing external load in volleyball.
The purpose of this study was to analyze competition jump load in collegiate volleyball players.
Data from nine National Collegiate Athletic Association (NCAA) Division I female volleyball players from the 2018 and 2019 competitive seasons were analyzed. Jumps were individually assigned, time-stamped, and recorded for height. Jump count and rate overall and at low, moderate, high, and maximal intensities were calculated. One-way ANOVAs were used to assess the variance in mean jump height from all jumps (HTall) and top five jump heights from each match (HTtop5) across positions (middle blocker vs. outside hitter vs. right-side hitter), timepoint in season (early vs. mid- vs. late), match length (3- vs. 4- vs. 5-set match), and Friday/Sunday matches and two-way ANOVAs were used to analyze jump count and rate differences across intensities.
Significant differences in HTall and HTtop5 across positions (P < 0.001) were shown. Main effects were found for jump count and rate by position (P < 0.001) and for jump count by match length (P < 0.001). Significant intensity × position interactions for jump count and rate by position (P < 0.001) and by timepoint (P < 0.01) and jump count by match length (P < 0.001) were found. No statistically significant variance was observed in HTall or HTtop5 based on timepoint (P > 0.05), HTall, HTtop5, or jump rate by match length (P > 0.05), or HTall, HTtop5, jump count, or jump rate between Friday/Sunday matches (P > 0.05).
Significant differences in competition jump height and load exist in NCAA Division I female volleyball players. Jump load alterations during training sessions may be warranted to maximize athlete readiness and performance.
The bench press is commonly used to measure upper-body strength. While much emphasis has been placed on the upper-body, little is known about how the lower-body can play a role in bench press performance. Leg-drive is a technique that includes flexing the knee so the feet line up posterior to the knee joint, while simultaneously contracting the knee extensors isometrically during the lift. The purpose of this study was to compare strength characteristics of lifters in a standard bench press versus a leg-drive bench press over the course of 5-weeks of training.
Twenty-three recreationally active males (age: 22.4 ± 2.1 years, height: 175.0 ± 5.9 cm, mass: 78.4 ± 9.5 kg) were randomized into a standard bench or leg-drive bench press group. Participants performed four sets to failure, two times per week for five weeks. Variables of interests were training volume and 1-repetition maximum (1RM) strength. For training volume, a 2 × 5 (group × week) repeated measures analysis of variance (RMANOVA) was used. For the 1RM’s, a 2 × 2 × 2 (group × press type × time) RMANOVA was used. A priori alpha levels were set to 0.05.
Over time, both groups showed an approximate 6% increase in 1RM strength. Training volume for week 4 was 5.6% less than week 5, but was not different from weeks 1 through 3. No between-group differences were observed for 1RM strength or training volume.
This results of this work indicates that 5 weeks of leg-drive training is effective in increasing 1RM strength, but was not more effective than standard bench press training. Practically, lifters should choose either lifting style based on personal preference.
To examine and compare the effects of three days of dynamic constant external resistance (DCER) and isokinetic (ISOK) training and subsequent detraining on thigh muscle cross-sectional area (TMCSA) and thigh lean mass (TLM), ISOK peak torque (PT), DCER strength, isometric force, muscle activation, and percent voluntary activation (%VA).
Thirty-one apparently-healthy untrained men (mean ± SD age = 22.2 ± 4.2 years; body mass = 77.9 ± 12.9 kg; height = 173.9 ± 5.4 cm) were randomly assigned to a DCER training group (n = 11), ISOK training group (n = 10) or control (CONT) group (n = 10). Subjects visited the laboratory eight times. The first visit was a familiarization session, the second visit was a pre-training assessment, the subsequent three visits were for unilateral training of the quadriceps (if assigned to a training group), and the last three visits were the post-training assessments conducted at three days, one week, and two weeks after training ended.
DCER strength increased from pre- to post-training assessment 1 in both limbs for the DCER group only, and remained elevated during post-training assessments 2 and 3 (P < 0.05). In addition, surface EMG for the biceps femoris was higher at post-training assessment 3 than at the pre-training assessment, and post-training assessments 1 and 2 (P < 0.05). No other training-related changes were found.
The primary finding of this study was that DCER strength of the trained and untrained limbs can be increased with three days of training. This has important implications for injury rehabilitation, where in the initial period post-injury strength gains on an injured limb can possibly be obtained with short-term contralateral resistance training.
The safety of creatine supplementation has been investigated, however, the safety of a high-dose/short-term or low-dose/long-term supplementation dosing scheme, combined with a resistance training program, a commonly used dosing scheme, has not yet studied. The aim of this study was to evaluate physical performance and the safety of the cited creatine supplementation dosing scheme in a double-blind placebo-controlled study by assessing blood and urine health indicators in subjects undertaking resistance training.
Thirty-four healthy male subjects were randomly assigned to creatine supplement (CREA/7 days, 0.3 g/kg body mass + 21 days, 0.03 g/kg) or placebo (PLA) group and both groups participated in a resistance training intervention (6 exercises, 3 sets of 8–12 repetitions per exercise at 85% of 1RM, 3 d/week). Blood and urine samples were collected pre-, 7 and 30 days post-supplementation. For blood (26 parameters) and urine markers (15), between-group differences were calculated by using 2 groups (CREA and PLA) × 2 measures (“POST7 minus PRE” and “POST30 minus PRE”) terms.
The CREA group exhibited significant body weight and 1RM increase (POST30 minus PRE) of all evaluated exercises, when compared to PLA group. Regarding the blood and urine health markers, only hematocrit, LDL, Uric Acid, Phosphatase Alkaline and Creatinine exhibited between-group differences, but with small magnitude of differences and maintained into the range of clinical reference values.
Our data suggest that creatine supplementation the used dosing scheme, concomitantly with resistance training, improves physical performance with no evident risk or protection to health for young weightlifters.
This study aimed to describe self-selected intensity and its relationship to performance during a high-intensity all-out judo protocol, and to verify whether athletes with different anaerobic speed reserve (ASR) perform differently during a high-intensity all-out interval uchi-komi (judo-specific skill).
We analyzed the performance of 28 judo athletes as a whole group and divided into groups, according to their ASR. They performed several judo-specific protocols using a specific skill: maximal speed sprint (MSS) and maximal aerobic speed (MAS), and high-intensity intermittent uchi-komi protocol (12 × 20 s all-out:10 s passive recovery).
The main results demonstrated a decrease in the number of repetitions and an increase in heart rate across the sets. Athletes with greater ASR performed a higher number of repetitions, compared to the low ASR group, and they were able to exercise at a higher percentage of the MAS (low ASR = 126%; SD = 13%; high ASR = 152%, SD = l9%) and at a lower percentage of MSS compared to the low ASR group (low ASR = 84%, SD = 7%; high ASR = 76%, SD = 11%). However, both groups exercised at a similar percentage of their own ASR during the protocol (low ASR = 50%, SD = 20%; high ASR = 53%, SD = 19%).
Athletes with different ASR seem to set their pace at around 50% of their ASR within an all-out uchi-komi protocol. Therefore, the ASR is useful for predicting performance during high-intensity judo-specific interval exercise intervals.
Left ventricular filling pressure (LVFP) is an important early indicator of heart failure that is more prevalent in Caucasians than Chinese. Exercise-induced change in LVFP may provide more incremental information to assess diastolic function. But it was unknown whether there was difference in LVFP following acute exercise between Caucasians and Chinese.
The purpose of this study was to investigate the change of LVFP following an acute 45-min aerobic exercise in healthy Caucasian and Chinese individuals.
Sixty participants (30 Caucasians and 30 Chinese, half was male, respectively) performed an acute bout of aerobic exercise at 70% of heart rate reserve. Hemodynamics, Left ventricle (LV) morphology and function parameters were measured at baseline, then at 30-min and 60-min post-exercise.
There was a similar LV ejection fraction, LV fraction shorten, lateral E/eʹ and lateral eʹ between Chinese and Caucasians at baseline. There was a significant race-by-time interaction in lateral E/eʹ and lateral eʹ between Chinese and Caucasians from pre-exercise to 30 min and 60 min after acute aerobic exercise. The ΔE/eʹ was significant correlated with baseline systolic blood pressure.
The change of LVFP was different between Chinese and Caucasians following acute aerobic exercise. The racial differences may be primarily caused by the changes of LV relaxation following exercise, baseline systolic blood pressure may also contribute to the differences.
The purpose of the present study was to investigate the association between cardiorespiratory fitness (CRF) measured as peak oxygen uptake (VO2peak, expressed in mL/min) and body mass index (BMI) in a large cohort of apparently healthy subjects.
BMI and VO2peak were measured in a cross-sectional study of 8470 apparently healthy adults. VO2peak (mL/min) was determined by an incremental cycle ergometer test to exhaustion. Linear regression analyses were performed to identify predictors of CRF.
There was no difference in CRF between adults with a normal weight (BMI between 18.5–24.9 kg/m2) and those who were overweight (BMI 25.0–29.9 kg/m2). Subjects who were underweight (BMI < 18.5 kg/m2) as well as females who were obese (BMI ≥ 30.0 kg/m2) showed a reduced CRF compared to the normal and overweight groups. Age, height, and gender were significant predictors of CRF (R 2 = 0.467, P < 0.0001); BMI did not add significantly to this relationship.
Our findings indicate that BMI was not associated with CRF in addition to age, height, and gender. In subjects with a BMI < 18.5 kg/m2, CRF was lower compared to subjects with a BMI between 18.5 and 29.9 kg/m2. In obese subjects, CRF was only lower in females compared to females with a BMI between 18.5 and 29.9 kg/m2. Correcting CRF for BMI may be beneficial for subjects with a low BMI, and females with a BMI ≥ 30.0 kg/m2. The outcome of this study might help to improve the interpretation of exercise testing results in individuals with a low or high BMI.