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.
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.
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.
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.