Competition and training demands of junior Sprint Kayak athletes

University of Technology, Sydney. Faculty of Health.Introduction: Sprint Kayak is an Olympic sport where women race over 200-m and 500-m and men compete over 200 and 1000-m. In 2009 the 200-m event was included into the Olympic Games’ program replacing the men’s 500-m events and providing the women with an additional event. Currently, little research is available on the demands of the 200-m event. With the inclusion of this short distance event, the training practices require review, especially in the case of young developing athletes, as this group may begin to specialise their training toward this new format. Therefore, the overall goals of this thesis were to: 1) gain a better understanding of the racing and physiological demands in Sprint Kayak, 2) develop specific methods for monitoring training and performance and 3) compare methods for training well-trained junior Sprint Kayak athletes. The results of four separate studies were reported in six manuscripts. Study 1: The split –time results from six Sprint Kayak world championships (ntotal = 486) were pooled and the pacing strategies and performance analysed according to race level (Finals A and B) and boat (K1, K2 and K4). Collectively, the world-class Sprint Kayak athletes present different pacing strategy according to final A and B), boat class (K1, K2 and K4) and from year to year. Study 2: Examined the relationships between physiological variables, including VO2max, maximal aerobic power (MAP), lactate threshold (LT2), whole body (VO2kinetics) and muscle oxygen kinetics (MO2kinetics), muscle oxygenation parameters and on-water time-trial performances. The results showed physiological variables correlated with performance in both 200-m and 1000-m events. Furthermore, the muscle oxygenation parameters increased the predictive power of these physiological variables highlighting the importance of muscle oxygen extraction for the 200-m time-trial. Study 3: Tested a specific performance test (SKtest) in the laboratory and in the field for validity (as a performance and fitness measure) and reliability (part A). In addition, the test sensitivity was assessed during a normal training period (part B) in a separate group of well-trained junior Sprint Kayak athletes. Part A - Participants (n = 11) completed a standard incremental kayak step test in the laboratory, a SKtest consisting of two sets of ten 100-m efforts with 20 s rest between efforts and 1000-m between sets in both laboratory and on-water and on-water time trials over 200 and 1000-m. Part B – Another group of athletes (n = 8) performed weekly trials of the short version of the SKtest for four weeks, in their usual training environment. The results showed the SKtest to be valid, reliable and sensitive for monitoring fitness and performance changes. Study 4: Tested the validity of methods for quantifying training load and established the relationships between training loads, physiological variables and on-water performance in well-trained junior Sprint Kayak athletes. The results demonstrated the validity of the session-RPE method for quantifying training loads in Sprint Kayak. Moreover, the inverse relationships between physiological variables, performance and training loads showed that aerobically fitter and faster athletes have lower perceived training loads when external loads are controlled. Study 5: Compared the power outputs and acute physiological responses (i.e. heart rate [HR], blood lactate [BLa¯], VO2, and tissue saturation index [TSI])) of common repeated sprint (RS) and high-intensity aerobic (HIA) interval training sessions in well-trained junior Sprint Kayak athletes. Two different RS training sessions consisting of a shorter 10 s repeat effort session (2 sets of 10 s efforts with 10 s rest between efforts and eight minutes between sets) and a longer 30-s repeat effort session (6 x 30 s efforts with 210 s rest). The HIA sessions included a shorter (2 x 3 min efforts with 3 min rest between efforts, and 5 min between sets) and a longer 2-km (3 x 2 km efforts on a 15 min cycle) interval training sets. The results showed the physiological responses and external loads to the main body the HIA interval sessions were considerably different from RS sessions, with the exception of TSI which was similar for all. Mixed modelling showed significant random variation for the time spent in different training zones for mean power output and VO2. The present study highlighted distinct differences in the HR, VO2, [BLa¯], and perceptual responses to common RS and HIA training, with the shorter RS sessions placing a greater stimulus on glycolytic pathways, and the longer HIA sessions requiring greater energetic demands. Importantly, large inter-individual physiological responses were observed across each of the different training sessions. These findings highlight the need to individualise training programs for Sprint Kayak based on the athletes’ characteristics and demands of competition. Study 6: Compared the effects of 5 weeks of RS and HIA interval training on physiological (VO2max, MAP, LT2, VO2kinetics and MO2kinetics) and performance (200 and 1000-m on water time trial) variables in well-trained junior Sprint Kayak athletes using matched-groups randomised design. The groups were matched for physical fitness and on-water kayak performance. In addition to their usual training, the RS training group completed a shorter 10 s repeat effort session (2 sets of 10 s efforts with 10 s rest between efforts and 8 minutes between sets) and longer 30-s repeat effort session (6 x 30 s efforts with 210 s rest), where each session was completed once per week. Similarly, the HIA interval training group completed a three-minute (2 x 3 min efforts with 3 min rest between efforts and 5 min between sets) and longer 2-km aerobic training (3 x 2 km efforts on a 15 min cycle) session once each week during the study in addition to their usual training. Results showed that the RS and HIA interval training interventions elicited trivial changes in maximal indicators of aerobic fitness (i.e. VO2max and maximal HR) and trivial and small on-water performance (i.e. time trials over 200 and 1000-m, respectively) in both groups. In contrast, submaximal physiological responses (i.e. lactate threshold) were trivial whereas oxygen kinetics presented small-to-moderate improvements after five weeks (~19 training sessions) performed by both RS and HIA groups. This information suggests that physiological and performance characteristics are very stable in well-trained junior Sprint Kayak athletes. It seems that either larger loads of RS or HIA interval training or longer training periods are required to elicit larger changes in specific physiological adaptations in well-trained junior Sprint Kayak athletes

Provocative Tests in the Diagnosis of Childhood Onset Growth Hormone Insufficiency

INTRODUCTION: The incidence of short stature associated with growth hormone deficiency has been estimated to be about 1:4000 to 1:10000. It is the main indication for treatment with recombinant growth hormone. OBJECTIVES: The aims of the study were to evaluate the results of growth hormone stimulation tests and identify the growth hormone deficiency predictors. MATERIAL AND METHODS: A cross-sectional, analytical and observational study was conducted. We studied all the children and adolescents submitted to growth hormone pharmacological stimulation tests between January 2008 and May 2012. Growth hormone deficiency diagnosis was confirmed by two negatives growth hormone stimulation tests (growth hormone peak < 7 ng/ml). The statistical analysis was performed using student t-test, chi-square, Pearson correlation and logistic regression. Statistical significance determined at the 5% level (p ≤ 0.05). RESULTS: Pharmacological stimulation tests were performed in 89 patients, with a median age of 10 [3-17] years. Clonidine (n = 85) and insulin tolerance test (n = 4) were the first growth hormone stimulation tests performed. Growth hormone deficiency was confirmed in 22 cases. In cases with two growth hormone stimulation tests, the growth hormone peak showed a moderate correlation (r = 0.593, p = 0.01). In logistic regression model height (z-score) and the growth hormone peak in first stimulation test were predictors of growth hormone deficiency diagnosis (each one unit increase in z-score decrease the growth hormone deficiency probability). DISCUSSION: Measurement of IGF-1 cannot be used in diagnosing growth hormone deficiency. CONCLUSION: Auxological criteria associated with a positive test seems to be a reliable diagnostic tool for growth hormone deficiency

H? filtering of time-varying systems with bounded rates of variation

In this paper, the problem of robust filter design for time-varying discrete-time polytopic systems with bounded rates of variation is investigated. The design conditions are obtained by using a parameter-dependent Lyapunov function and the Finsler\u27s Lemma. A robust filter, that minimizes an upper bound to the H? performance of the estimation error, is obtained as the solution of an optimization problem. A more precise geometric representation of the parameter time variation was used in order to obtain less conservative design conditions. Robust filters for time-invariant, as well as arbitrarily time-varying, polytopic systems can be obtained as a particular case of the proposed method. Numerical examples illustrate the results

Aplicação de métodos geofísicos em Arqueologia: desenvolvimento de metodologias eficazes de prospecção geofísica aplicadas a diferentes ambientes arqueológicos

The use of geophysical methods applied to Archaeology, in the exploration of buried structures in the sub-surface, is an imperative need in the previous steps to excavations or archaeological surveys, playing an important role in the delimitation of archaeological sites, making it more effective protective actions archaeological heritage. With regard to planning an archaeological exploration, geophysical methods significantly reduce the runtime and operating costs, guiding with acceptable accuracy for local archaeologist digging and what to look for. The development of efficient methods in geophysical exploration, applied to different archaeological environments usually requires the crossing of different geophysical techniques. The methodologies for the application of geophysical surveys shall concern either in the steps of the data acquisition either in the steps of the obtained data processing and in the result representation. This work presents the results for two techniques, georadar and magnetometry, in different archaeological locations, showing the differences between the different archaeological sites, whose features are different

H? robust memory controllers for networked control systems: uncertain sampling rates and time delays in polytopic domains

In this paper, the problem of controller design for networked control systems with time-varying sampling rates and time delays is investigated. By using a memory at the feedback loop, a digital robust controller that minimizes an upper bound to the Hinfin performance of the closed loop system is determined. The design conditions are obtained from the Finsler\u27s Lemma combined with the Lyapunov theory and expressed in terms of bilinear matrix inequalities. Extra variables introduced by the Finsler\u27s Lemma are explored in order to provide a better system behavior. The time-varying uncertainties are modelled using polytopic domains. The controller is obtained by the solution of an optimization problem formulated only in terms of the vertices of the polytope, avoiding grids in the parametric space. Numerical examples illustrate the efficiency of the proposed approach

H? filtering of networked systems with time-varying sampling rates

In this paper, the problem of robust filter design for networked systems with time-varying sampling rate is investigated. The design conditions are obtained by using the Lyapunov theory and the Finsler\u27s Lemma. A robust filter, that minimizes an upper bound to the Hinfin performance of the estimation error, is obtained as the solution of an optimization problem. A path-dependent Lyapunov function is used in order to obtain less conservative design conditions. Robust filters based on affine parameter-dependent Lyapunov functions can be obtained as a particular case of the proposed method. Numerical examples illustrate the results

H? Gain Scheduling for Discrete-Time Systems with Control Delays and Time-Varying Parameters: a BMI Approach

In this paper, the problem of gain scheduling for time-varying systems with time delays is investigated. By using a memory at the feedback loop, a discrete gain scheduled controller which minimizes an upper bound to the ,Hscrinfin performance of the closed loop system is determined. The design conditions, expressed in terms of bilinear matrix inequalities, are obtained from the Finsler\u27s Lemma combined with the Lyapunov theory. The extra variables introduced by the Finsler\u27s Lemma represent an alternative way in the search of better system behavior. The time-varying uncertainties are modeled using polytopic domains. The controller is obtained by the solution of an optimization problem formulated only in terms of the vertices of the polytope. No grids in the parametric space are used. Numerical examples illustrate the efficiency of the proposed approach

Data on metabolic profile of insulin-degrading enzyme knockout mice

Insulin-degrading enzyme (IDE) degrades and inactivates bioactive peptides such as insulin. As insulin is a master regulator of glucose homeostasis, lack of IDE is expected to have a profound impact on both insulin and glucose levels. This article shares data on glucose and insulin homeostasis of control, heterozygous and knockout mice for Ide after 18 weeks of a normal chow diet. This data article is related to a research article entitled “Knockout of insulin-degrading enzyme leads to mice testicular morphological changes and impaired sperm quality” (Meneses et al., 2019).This work was supported by FEDER funds POCI - COMPETE 2020 , Portugal: Project POCI-01-0145-FEDER-007491 ; and by “ Fundação para a Ciência e a Tecnologia ” – FCT to MJM ( PD/BD/114256/2016 ); TRD ( SFRH/BD/109284/2015 ); PFO ( PTDC/BBB-BQB/1368/2014 ; IFCT2015); MPM ( PTDC/DTP-EPI/0207/2012 ; PTDC/BIM-MET/2115/2014 ); MGA ( PTDC/BIM-MET/4712/2014 ; IFCT2015); iNOVA4Health ( UID/Multi/04462/2013 ); and UMIB ( PEst-OE/SAU/UI0215/2014 )