It is of great importance to be able to unambiguously interpret deoxyribonucleic acid (DNA) profiles, especially with Low Template (LT) DNA and mixture DNA that may contain major and minor contributors. Reducing stochastic effects, such as heterozygote peak imbalance, dropouts, and stutter artifacts have been studied by scientists in order to improve the evaluation of low quality DNA profile. There has been much research on a compatible solute, trehalose, in its effectiveness in enhancing the polymerase chain reaction (PCR), especially with GC-rich templates of DNA, and thermal stabilizing Thermus Aquaticus (Taq) DNA polymerases. Based on previous research, the effect of trehalose on peak heights, peak height ratios, and stutter ratios (n-1) from 15 short tandem repeats (STR) loci of the AmpFℓSTR® Identifiler® Plus PCR Amplification Kit was evaluated with 0.025ng, 0.05ng, 0.1ng, and 1ng of DNA, through the addition of 0M (control), 0.2M, and 0.4M of trehalose for each quantity of DNA. Although there was an observation regarding changes in average peak heights at 1ng of DNA with the addition of 0.2M, and 0.4M of trehalose, no conclusions could be made with the average peak heights for 0.025ng, 0.05ng, 0.1ng, and 1ng of DNA. The reason is that the propagation of pipetting error during the preparation of each batch could have contributed to the difference in the amount of DNA between each conditions which can be directly reflected in peak heights. Furthermore, unexpected discrepancy between the average peak heights for 0.1ng of DNA from the first and the second experiments rendered 0.1ng of DNA incompatible for comparison. With regards to average peak height ratios for 0.025ng, 0.05ng, 0.1ng, and 1ng of DNA, and average reverse stutter ratios for 0.1ng, and 1ng of DNA, there were no evidence to suggest that 0.2M or 0.4M of trehalose had any effects. Consistent trends for 0.1ng (Exp. 1 and 2) and 1ng of DNA from a statistical analysis through one-way ANOVA of individual loci, suggested that trehalose may have varying effects on certain loci. However, this observation must be approached with caution as it is uncertain whether unique trends across each data sets for certain loci were observed by chance due to small sample sizes or due to mechanisms of stutters and trehalose that are currently unknown. Future studies regarding the effect of trehalose on peak heights should be done with more precision through minimizing pipetting error, which can be accomplished by preparing one batch from which aliquots are taken. The result of the research does not show enough evidence to prove the usefulness of trehalose since the addition of trehalose does not yield consistently higher average peak heights and peak height ratios, and lower average reverse stutter ratios across 15 STR loci. Therefore, our results do not support that 0.2M and 0.4M of trehalose are useful within the parameter of forensic DNA analysis as they do not enhance the polymerase chain reaction (PCR) and improve stochastic effects for DNA profiles.

Le but de ce travail est de réaliser une étude approfondie des caractéristiques morphologiques des footballeurs algériens de 15-16 ans en vue d’améliorer les processus de détection et de formation de l’élite nationale. Pour cela, cette thèse repose sur deux études qui permettent d’une part de tracer le profil type des jeunes footballeurs Algériens et d’autre part d’évaluer l’influence de la maturation précoce ou tardive sur la sélection en équipe nationale. L’objectif de la première étude est la détermination du profil morphologique des jeunes footballeurs algériens de 15-16 ans où nous avons pris un échantillon de 146 joueurs ayant une moyenne d’âge de (15,61 ans ± 0,49), dont 25 font partie de l’équipe nationale (U-17) et 121 évoluant dans les quatre régions du pays (Est, Ouest, Centre et Sud). Nous nous sommes basés sur la méthode anthropométrique afin de pouvoir déterminer les différences morphologiques existantes entre les joueurs suivant le niveau de pratique et les compartiments de jeu. La comparaison entre les sélections par régions et les données de l’équipe nationale, nous renseigne sur la différence du niveau du développement morphologique existant. Ce dernier est en faveur de la sélection nationale, exception faite pour la sélection Est qui s’en rapproche. Selon les postes de jeu, nous constatons que résultats des jeunes footballeurs algériens de moins de 17 ans, sont conforment aux exigences du football par poste de jeu, définis par plusieurs auteurs. Cette étude, par rapport aux données internationales exploitées, met en évidence des différences significatives pour les indices du développement physique, ce qui confirme la faiblesse de nos jeunes joueurs. L’analyse en composantes principales a permis de choisir 20 paramètres, estimés comme les plus représentatifs du développement morphologique de nos jeunes joueurs. Cette sélection de paramètres nous a permis de dégager un profil type du jeune footballeur algérien. Le deuxième volet de notre étude s’articule autour de l’influence de l'âge, des dimensions corporelles et des stades de maturation sur la sélection des jeunes footballeurs algériens âgés de moins de 17 ans en équipe nationale en comparant leurs résultats a ceux des équipes régionales du pays. Quatre-vingt onze jeunes footballeurs algériens (28 internationaux et 63 régionaux) ont été étudiés (âge moyen = 16,6 ans). L’âge du pic de croissance (PHV) a été déterminé selon l'équation de Mirwald et al. (2002). Les deux groupes sont d'âge chronologique similaire mais les joueurs appartenant à l'équipe nationale sont significativement plus matures que les joueurs de la sélection régionale (P <0,01). […] Les présents résultats démontrent que dans le football, le développement physique avancé est un avantage certain pour accéder aux meilleures équipes, […] que le développement morphologique précoce est une caractéristique importante que les entraîneurs détectent de façon plus ou moins consciente dans leur recherche des «jeunes talents». D’un point de vue général, ce travail souligne l’importance de l’élaboration du profil morphologique du jeune footballeur algérien de 15-16 ans pour servir de base de référence aux entraineurs et aux scientifiques. L’influence de la croissance et de la maturation sur la performance étant un fait avéré, une des principales conditions de l’efficacité du système de détection et de préparation de nos jeunes footballeurs consisterait en un contrôle rigoureux de l’âge biologique. Une classification rationnelle, prenant compte les stades de maturation et le développement harmonieux des qualités physiques, permettrait de résoudre correctement les questions posées par la sélection sportive et l’orientation des jeunes footballeurs à savoir, la déperdition des talents et les blessures. Une des perspectives de ce travail sera de rechercher les causes physiologiques des lacunes morphologiques du jeune footballeur algérien qui font obstacle au bon déroulement de son processus de formation. / The aim of this work is to perform a comprehensive study of morphological characteristics of Algerian soccer players’ aged 15-16 years to improve the detection process of the national elite. To do this, this thesis is based on two studies that allow one hand to trace the typical profile of young Algerians soccer players and secondly to assess the influence of early and late maturation on selection for of national team.The objective of the first study is to determine the morphological profile of young Algerian soccer players aged 15-16 years where we took a sample of 146 players with an average age (15.61 years ± 0.49), 25 of which are part of the national team (U-17) and 121 stocks in the four regions (Eastern, Western, Central and South). We relied on anthropometric method in order to determine the morphological differences existing between players depending on the level of practice and compartments. The comparison between selections by region and data from the national team, tells us about existing differences in level of morphological development, except for East regional selection. Depending on the position of play, we find that outcomes for young Algerian soccer players less than 17 years shall comply with the requirements of the post football game, set by several authors. This study, compared to international data used, highlights significant differences in the indices of physical development, which confirms the weakness of our young players. Principal component analysis allowed the selection of 20 parameters, estimated as the most representative of the morphological development of our young players. With this selection of parameters we have identified a typical profile of young Algerian soccer players.The second part of our study focuses on the influence of age, body dimensions and stage of maturation on the selection of young Algerian soccer players aged Under-17 national team, by comparing their results to those of regional teams. Ninety-one young Algerian soccer players (28 international and 63 regional) were studied (mean age = 16.6 years). The age of peak height velocity (PHV) was determined by the equation of Mirwald et al. (2002). The two groups are similar chronological age but the players belonging to the national team are significantly more mature than the regional one (P <0.01). [...] These results show that in football, developing advanced physics is an advantage to access the best teams, [...] that the early morphological development is an important feature that coaches detect more or less conscious in their search for "young talent".From a general point of view, this work highlights the importance of the assessment of the morphological profile of young Algerian soccer players aged 15-16 to serve as a baseline for coaches and scientists. The influence of growth and maturation performance is a fact, one of the main conditions for the effectiveness of the detection system and preparing our young players would be a strict monitoring of biological age. A rational classification, taking into account the stages of maturation and harmonious development of physical qualities, would properly resolve the loss of talent and injuries. A perspective of this work is to investigate the physiological causes of morphological gaps of the young Algerian soccer players who impede the smooth functioning of its training process.

Thesis (M. Sc. (Statistics)) -- University of Limpopo, 2018 / TheEllisrasLongitudinalStudy(ELS)openedthepossibilitiesforunderstandingthegrowthvariationsamongchildreninruralSouthAfrica. Theaimofthe study was to analyse the growth spurt in height and weight of children using the ELS. This is part of the on going ELS and this study followed secondary analytical longitudinal study using data collected from November 1996 to November 2003. All children underwent a series of anthropometric measurements of height and weight according to the standard procedures recommended by the International Society for the Advancement of Kinanthropometry. The descriptive statistics was done for age, height, weight, velocity and acceleration by gender amongst rural children in Ellisras. Thelinearmixedmodelwasusedto analyse data. Based on the smallest values of AIC and BIC, the best model to fit the ELS data which was found to be the unstructured covariance structure model was chosen. The interaction between age and gender, which was significant at 5% level suggested that the relationship of age with growth varies depending on gender. There was also a significant positive linear relationship of age with distance. The onset of growth spurt for rural children in Ellisras was at 12.05 years for boys and at 12.32 years for girls, while the Senegalese boys took off earlier at 11.02 years. Ellisras rural boys and USA boys had their onset of growth spurt almost at the same age at 13 years for USA boys and 12.05 years for Ellisras rural boys. USA girls had their onset of growth spurt earlier at 11 years than Ellisras rural girls at 12.32 years. Newcastle upon Tyne adolescents reached ii their PHV at 14 and 12 years for boys and girls respectively, similarly with Ellisras rural children at 14.21 and 11.80 years for boys and girls respectively. Ellisras rural girls had their PHV at 11.80 years earlier than Ellisras rural boys at 14.21 years. Children in rural Ellisras in the ELS and their growth variations do not differ that much compared with other children across the world. Key words: Growth spurt, peak height velocity, boys, girls. / National Research Foundation (NRF)

Aim The aim of this study was to investigate the effect of flywheel resistance training on functional neuromuscular performance in physically active youth.   Method Forty-four healthy and physically active youth between 12-14 years of age (n=19 boys &amp; n=25 girls) volunteered to participate and were randomized into three different groups of flywheel resistance training (FRT) (n=15, body mass = 42,9 ± 8,6 kg, time to Peak Height Velocity (PHV) = - 0,8 ± 1,6), traditional strength training (TST) (n=15, body mass = 44,7 ± 10,3 kg, time to PHV = - 0,8 ± 1,5) and a control group (CON) (n=14, body mass = 43,8 ± 9,0 kg, time to PHV- 0,8 ± 1,5. Squat jump (SQ), Countermovement jump (CMJ), 10-m acceleration, 20-m speed and 30-sprint was assessed pre- and post-intervention. All training groups performed 12 resistance training sessions over a 6-week intervention. The FRT-group performed bilateral flywheel resistance squats with 4 sets of 6 repetitions with 0,025 to 0,05 kgm2 and the TST-group performed bilateral barbell squats with 4 sets of 6 repetitions at a predicted 80 %1RM, while the control group only performed their regular sports training.   Results Repeated measures two way-ANOVA, 3 x 2 (training group x time), showed no significant mean effects between groups after the intervention. A significant increase occurred in the control group for SQ; 2,4 ± 2,5 (cm) p ≤ 0,008 and CMJ; 2,2 ± 3,1 (cm) p ≤ 0,037. Both training groups increased significantly in body mass from pre- to post-tests by 2,0 ± 2,7 kg for the flywheel training group and 1,3 ± 0,9 kg in the traditional strength training group (p ≤ 0,05).   Conclusions This study indicates that flywheel training can be used as a resistance training method for youth athletes without inducing training related injuries. Flywheel resistance training resulted in a small but non-significant increase from pre to post test in squat jump and 10-m sprint. Future studies on flywheel resistance training for youth needs to investigate the implementation of longer training periods, additional training sessions, more experienced youth in resistance training and faster movement speed.

Sammanfattning Syfte och frågeställningar Syftet med denna studie var att undersöka vilken eller vilka somatiska mätmetoder som har störst tillämpbarhet för att praktiskt genomföra en biologisk åldersuppskattning för en tränare. Metod För att besvara studiens frågeställning har sökningar genomförts i databaserna PubMed och Google Scholar. Information har även sökts i relevant facklitteratur inom barn- och ungdomsträning samt i relevanta studiers referenslistor. Resultat Tre somatiska mätmetoder kunde presenteras i form av tid för högst tillväxtspurt (PHV) av Mirwald et al (2002), Fysiskt utvecklingsindex (KEI) av Bauer från 1982 (Tonkonogi &amp; Bellardini 2012, s 25) och uppskattad vuxenlängd mot Tannerkriterierna (PAH) (Khamis &amp; Roche 1995; Cumming et al 2017). Resultatet indikerar att KEI-metoden är den mätmetod som har störst validitet (r &gt; 0,89). För praktisk tillämpbarhet verkar en kombination av PHV och PAH-metoderna vara mest lämpad för en biologisk åldersuppskattning för tränare i en fältmiljö. Slutsats Studiens slutsats är att tränare rekommenderas att använda sig av en kombination av PHV och PAH. De är två metoder som används flitigt inom den internationella litteraturen och verkar kunna användas ihop för att indikera tiden för PHV, som är en frekvent använd indikator för vilka delkapaciteter som är träningsbara för en individ i puberteten. Nyckelord: biologisk ålder, peak height velocity, predictive adult height, tannerkriterierna

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