Impacts of Creatine Supplementation on Body Weight and Running Anaerobic Sprint Performance Test (RAST) Time Performance in Youth Soccer Players

Creatine supplementation commonly increases intracellular water and/or lean mass-associated weight gain and concomitantly improved short-term, high-intensity effort performance such as repeated sprint ability. Research in this regard is both generally sparse but specifically more so in younger soccer athletes. PURPOSE: to determine the effect of 28 days of creatine monohydrate supplementation on body weight and running anaerobic sprint performance (RAST) time in youth soccer players. METHODS: Sixteen male youth soccer players were randomized in double-blinded fashion to either 28 days of creatine supplementation (CRE; 15.9±0.35y) or an equivalently-dosed dextrose (PLA; 15.5±0.54y; 0.3g/kg/d for the first 7 days, followed by 0.03g/kg/d for the remaining period), whereby they maintained their typical diet and training routines throughout the study. Furthermore, all subjects measured their weight and performed two RASTs both prior to (PRE) and following (POST) supplementation, consisting of 10 second rest intervals between six maximal 35m runs. RAST time was determined via a Speed Test FIT CEFISE photocell system. Due to the nonparametric nature of the data, individual Friedman’s ANOVA were employed to assess both within-group PRE-to-POST supplementation results (weight and 35m time within the same ordered RAST sprint), as well as any potential differences between the six maximal 35m runs at a significance level of p\u3c.05. RESULTS: Analyses revealed a significant change in body weight (p\u3e.001; Cohen’s D=.409) in CRE that was not observed in PLA (1.09±0.314kg vs -0.08±0.259kg). Conversely, there were no significant within-group differences between the PRE-to-POST-supplementation sprint times (p\u3e.05), but the sixth sprint was statistically slower than the first in either condition (p\u3c.05). CONCLUSION: Although creatine supplementation did not meaningfully enhance RAST-associated sprint times in the present investigation, it did corroborate previous literature via increased body weight in youth soccer athletes. Notwithstanding our equivocal findings, future research should continue to elucidate the impact of this otherwise extensively studied ergogenic aid in this demographic by employing a standardized training protocol to further eliminate possible extraneous variables

Wind-assisted ship propulsion of a series 60 ship using a static kite sail

Following the International Maritime Organization’s goal to reduce greenhouse gas emissions, the interest in the application of wind-assisted ship propulsion (WASP) in maritime transportation is on the rise. Although a variety of WASP systems exist, the application in maritime shipping is still limited, especially in the case of kite sails. This paper presents a numerical model to carry out a theoretical assessment of the influence of the kite planform area and wind speed on the aerodynamic performance of a kite sail providing propulsive assistance to a 75 m long ship having a Series 60 hull. A static kite sail is assumed, on which a tail wind generates a thrust force to pull the vessel via a tether. While the mass of the kite is neglected, that of the tether is accounted for. A model is implemented for the tensioned tether having a catenary profile. The results generally show a positive correlation between the aerodynamic forces and the kite parameters. As expected, the output parameter values corresponding to the optimal angle of attack for a range of vessel speeds are also found to increase with an increasing relative wind speed. It is concluded that a static 320 m2 kite sail would be sufficient to meet the entire propulsion requirements of the vessel under consideration under appropriate wind conditions.peer-reviewe

Impacts of Creatine Supplementation on Running Anaerobic Sprint Performance Test (RAST) Power and Velocity in Youth Soccer Players

Creatine supplementation commonly enhances short-term, high-intensity effort performance such the soccer-specific ability to perform repeated sprints. Research in this regard is both generally sparse but specifically more so in youth athletes. PURPOSE: to determine the effect of 28 days of creatine monohydrate supplementation on running anaerobic sprint performance (RAST) power and velocity in youth soccer players. METHODS: Sixteen male youth soccer players were randomized in double-blinded, parallel-group fashion to either 28 days of creatine supplementation (CRE; 15.9±0.35y) or an equivalently-dosed dextrose (PLA; 15.5±0.54y; 0.3g/kg/d loading dose for the first seven days, followed by 0.03g/kg/d for the remaining period), whereby they maintained their typical diet and training routines throughout the study. Furthermore, all subjects measured their weight and performed two RAST tests both prior to (PRE) and following (POST) supplementation, consisting of 10 second rest intervals between six maximal 35m runs. RAST peak and mean values for power and velocity were determined via a Speed Test FIT CEFISE photocell system. Due to the data’s distribution, individual appropriate within- and between-group nonparametric analyses were employed to assess PRE-to-POST supplementation mean and peak power (mP and pP) and velocity (mV and pV) at a significance level of p\u3c.05. RESULTS: Neither power parameter (mP and pP) nor pV differed PRE-to-POST or between groups (p\u3e.05). Nevertheless, nonparametric analyses revealed statistically significant mV differences (p=.025), whereby post-supplementation CRE was greater (23.7±1.64km/h) compared to both PRE in either group (CRE-PRE: 22.9±1.81km/h; PLA-PRE: 22.1±0.638km/h) and relative to PLA post-supplementation (22.2±1.15km/h). CONCLUSION: Although creatine supplementation did not meaningfully enhance RAST-associated power nor peak velocity, it did enhance mean velocity in youth soccer athletes. Notwithstanding our limited ability to claim a creatine-mediated performance advantage in this and similar demographics, future research should corroborate and further support these data by employing a standardized training protocol to eliminate additional extraneous variables

Preliminary analysis on the hydrostatic stability of a self-aligning floating offshore wind turbine

There exist vast areas of offshore wind resources with water depths greater than 100 m that require floating structures. This paper provides a detailed analysis on the hydrostatic stability characteristics of a novel floating wind turbine concept. The preliminary design supports an 8 MW horizontal-axis wind turbine with a custom self-aligning single-point mooring (SPM) floater, which is to be constructed within the existing shipyard facilities in the Maltese Islands, located in the Central Mediterranean Sea. The theoretical hydrostatic stability calculations used to find the parameters to create the model are validated using SESAM®. The hydrostatic stability analysis is carried out for different ballast capacities whilst also considering the maximum axial thrust induced by the rotor during operation. The results show that the entire floating structure exhibits hydrostatic stability characteristics for both the heeling and pitching axes that comply with the requirements set by the DNV ST-0119 standard. Numerical simulations using partial ballast are also presented.peer-reviewe

A review of ship-to-ship interactions in calm waters

The hydrodynamic interaction between two or more ships in harbours or inland waterways is a classical maritime engineering research area. In ship manoeuvring practice, ship masters try to determine the speed and gap limit when a ship is passing or encountering others, particularly in confined water ways. This requires an accurate prediction of the interaction force acting on both ships. The pioneer experimental studies showed that the interaction could lead to a very large yaw moment and this moment is strongly time-dependent, which could make the ships veer from their original courses, leading to collisions. Based on the findings on experimental measurements, some empirical formulas are proposed in the literature to predict such interaction forces. However, these formulas could provide a satisfactory estimation only when the ship speed is quite high, and the water depth is shallow and constant. Numerical simulation overcomes this issue by simulating the ship-to-ship problem by considering the effect of the 3D ship hull, variable water depth and ship speed. Numerical simulation has now become the most widely adopted method to investigate the ship-to-ship problem. In the present study, the development of the methodologies of ship-to-ship problems will be reviewed, and the research gap and challenges will be summarized.peer-reviewe

A numerical analysis of dynamic slosh dampening utilising perforated partitions in partially-filled rectangular tanks

Conventional liquefied natural gas (LNG) cargo vessels are imposed with tank-fill limitations as precautions to prevent structural damage and stability-loss due to high-impact sloshing, enforcing cargo volume-fills to be lower than 10% or higher than 70% of the tank height. The restrictions, however, limit commercial operations, specifically when handling spot trades and offshore loading/unloading at multiple ports along a shipping route. The study puts forward a computational fluid dynamic (CFD) sloshing analysis of partially-filled chamfered rectangular tanks undergoing sinusoidal oscillatory kinetics with the use of the explicit volume-of-fluid and non-iterative time-advancement schemes utilising the commercial solver ANSYS-Fluent. Establishing a 20% to 60% fill-range, the sloshing dynamics were acknowledged within an open-bore, partitioned, and perforated-partitioned tank when oscillating at frequencies of 0.5 Hz and 1 Hz. The overall torque and static pressure induced on the tank walls were investigated. High-impact slamming at the tank roof occurred at 40% and 60% fills, however, the implementation of the partition and perforated-partition barriers successfully reduced the impact due to suppression and dissipation of the wave dynamics.peer-reviewe