The metabolic syndrome has become a major public health challenge world-wide and, at least in the industrialized world, the prevalence of the metabolic syndrome is increasing. There is evidence to show that biological and lifestyle risk factors for metabolic syndrome are present in adolescence, which suggests that the antecedents of the disease may lie in early life. The period of adolescence is characterized by a decline in physical activity (PA; lack of PA is a lifestyle risk factor for metabolic syndrome) and an increase in fat mass deposition (a biological risk factor for metabolic syndrome). Therefore, investigating how the development of these two variables relates to adult cardiometabolic risk is important to fuel early intervention. A factor which has the potential to influence these two risk factors, and thus ultimately the metabolic syndrome, is the timing of biological maturity (i.e. whether an individual is early, average or late maturing when compared to peers of the same age). The influence of biological maturity has largely been overlooked in previous research; therefore, the general objective of this thesis was to investigate the associations between biological maturity, adolescent PA and fat mass development, and young adult cardiometabolic risk. Three studies were necessary to realize this objective, and together help to elucidate the role of biological maturity in the adolescent decline in physical activity, fat development, and the development of adult metabolic syndrome. Ultimately, this information will aid in the development and implementation of interventions to decrease prevalence of metabolic syndrome.<p> Study 1: The purpose of study 1 was to investigate whether observed gender differences in objectively measured PA in children (8 to 13 years) are confounded by biological maturity differences. Methods: Four hundred and one children (194 boys and 207 girls) volunteered for this study. An Actigraph accelerometer was used to obtain 7 consecutive days of minute-by-minute PA data on each participant. Minutes of moderate to vigorous PA per day (MVPA), continuous minutes of MVPA per day (CMVPA), and minutes of vigorous PA per day (VPA) were derived from the accelerometer data. Age at peak height velocity (APHV), an indicator of somatic maturity, was predicted and individuals aligned by this biological age (years from APHV). Gender differences in the PA variables were analyzed using a two-way (gender X age) ANOVA. Results: Levels of PA decreased with increasing chronological ages in both genders (p<0.05). When aligned on chronological age, boys had a higher MVPA at 10 through 13 years, a higher CMVPA at 9 through 12 years, and a higher VPA at 9 though 13 years (p<0.05). When aligned on biological age, PA declined with increasing maturity (p<0.05); however gender differences between biological age groups disappeared. Conclusion: The observed age-related decline in adolescent boys and girls PA is antithetical to public health goals and as such is an important area of research. In order to fully understand gender disparities in PA, consideration must be given to the confounding effects of biological maturity.<p> Study 2: Understanding the influence of biological age (BA) on the decline in PA would better inform researchers about the effective timing of intervention. The purpose of study 2 was to describe the PA levels and perceived barriers to PA of adolescent girls grouped by school grade and biological maturity status (i.e., early or late maturing) within grades. Methods: 221 girls (aged 8-16 years; grades 4-10) wore an Actical accelerometer for 7 days and then completed a semi-structured, open ended questionnaire on perceived barriers to PA over the 7 day period. Predicted APHV and recalled age at menarche were used to assess maturity among the elementary and high school girls, respectively. Maturity and grade group differences in PA were assessed using MANCOVA and independent sample t-test, and barriers to PA using chi squared statistics. Results: Daily minutes spent in MVPA decreased by 40% between grades 4 to 10. Within grade groupings, no differences in PA were found between early and late maturing girls (p>0.05). Grades 4-6 participants cited more interpersonal (i.e., social) barriers. Grades 9-10 participants cited more institutional barriers to PA, primarily revolving around the institution of school. No differences were found in types of barriers reported between early and late maturing girls. Conclusion: Since PA and types of perceived barriers to PA were dependent on grade, future research should work to identify the most salient (i.e., frequent and limiting) barriers to PA by chronological age in youth.<p> Study 3: Although the metabolic syndrome is thought to be mainly a consequence of obesity, the mechanisms underpinning its development are not that well understood. The purpose of study 3 was to examine total body fat mass (FM), trunk FM and PA developmental trajectories (aligned to BA; years from APHV) of individuals categorized as low and high for cardiometabolic risk at 26 years, while investigating biological and lifestyle risk factors. Methods: The sample were 55 males and 76 females from the Saskatchewan Pediatric Bone Mineral Accrual Study (1991-2007) who were assessed from childhood to young adulthood and had a measure of cardiometabolic risk at young adulthood (26.0 + 2.3 yrs). Height was measured biannually. Total body FM and trunk FM was assessed annually by dual energy-X-ray absorptiometry. PA and dietary intake was evaluated two to three times annually using surveys. Individuals were grouped into maturity status groups (early, average or late) depending on their APHV. Two composite cardiometabolic risk scores were calculated for males and females separately. The first was derived for a sub-sample (N=48) by summing the standardized residuals of inverted high-density lipoprotein cholesterol, homeostasis model assessment for insulin resistance, mean arterial pressure (MAP) and fasting triglyceride levels. A second score was derived for the whole sample by summing the standardized residuals for MAP. Scores for both samples were regressed on to age and adult smoking status. High and low cardiometabolic risk groups were determined based on a sex- specific median split of risk scores. Data were analyzed using random effects models. Models were built in a stepwise procedure with predictor variables added one at a time, using the log likelihood ratio statistic to determine if one model was a significant improvement over the previous one. Results: The final model indicated that once the independent effects of maturity (years from APHV) and height were controlled, the high risk group males and females had significantly (p<0.05) greater total body FM and trunk FM development at all ages. No association was found between young adult cardiometabolic risk and development of PA. Furthermore, in general, timing of biological maturity was not associated with development of PA or FM. Conclusion: Young adults at higher cardiometabolic risk have greater body fat as early as 8 years of age, which lends support to early intervention.<p> General Conclusions: Adolescence has been highlighted as a critical period for the development of adult disease, such as the metabolic syndrome. Results from this thesis support this contention by showing a decrease in PA (by both chronological and biological age) in males and females across adolescence. It further showed that an increase in total and central fatness during adolescence may be critical for the development of the metabolic syndrome in adulthood. Timing of biological maturity, in general, was not shown to have an independent impact on adolescent or young adult PA, adolescent perceived barriers to PA, fat mass development, or young adult cardiometabolic risk. However, further research is required before definitive conclusions can be made about the short and long term impacts of timing of biological maturity on health.

The metabolic syndrome has become a major public health challenge world-wide and, at least in the industrialized world, the prevalence of the metabolic syndrome is increasing. There is evidence to show that biological and lifestyle risk factors for metabolic syndrome are present in adolescence, which suggests that the antecedents of the disease may lie in early life. The period of adolescence is characterized by a decline in physical activity (PA; lack of PA is a lifestyle risk factor for metabolic syndrome) and an increase in fat mass deposition (a biological risk factor for metabolic syndrome). Therefore, investigating how the development of these two variables relates to adult cardiometabolic risk is important to fuel early intervention. A factor which has the potential to influence these two risk factors, and thus ultimately the metabolic syndrome, is the timing of biological maturity (i.e. whether an individual is early, average or late maturing when compared to peers of the same age). The influence of biological maturity has largely been overlooked in previous research; therefore, the general objective of this thesis was to investigate the associations between biological maturity, adolescent PA and fat mass development, and young adult cardiometabolic risk. Three studies were necessary to realize this objective, and together help to elucidate the role of biological maturity in the adolescent decline in physical activity, fat development, and the development of adult metabolic syndrome. Ultimately, this information will aid in the development and implementation of interventions to decrease prevalence of metabolic syndrome.<p> Study 1: The purpose of study 1 was to investigate whether observed gender differences in objectively measured PA in children (8 to 13 years) are confounded by biological maturity differences. Methods: Four hundred and one children (194 boys and 207 girls) volunteered for this study. An Actigraph accelerometer was used to obtain 7 consecutive days of minute-by-minute PA data on each participant. Minutes of moderate to vigorous PA per day (MVPA), continuous minutes of MVPA per day (CMVPA), and minutes of vigorous PA per day (VPA) were derived from the accelerometer data. Age at peak height velocity (APHV), an indicator of somatic maturity, was predicted and individuals aligned by this biological age (years from APHV). Gender differences in the PA variables were analyzed using a two-way (gender X age) ANOVA. Results: Levels of PA decreased with increasing chronological ages in both genders (p<0.05). When aligned on chronological age, boys had a higher MVPA at 10 through 13 years, a higher CMVPA at 9 through 12 years, and a higher VPA at 9 though 13 years (p<0.05). When aligned on biological age, PA declined with increasing maturity (p<0.05); however gender differences between biological age groups disappeared. Conclusion: The observed age-related decline in adolescent boys and girls PA is antithetical to public health goals and as such is an important area of research. In order to fully understand gender disparities in PA, consideration must be given to the confounding effects of biological maturity.<p> Study 2: Understanding the influence of biological age (BA) on the decline in PA would better inform researchers about the effective timing of intervention. The purpose of study 2 was to describe the PA levels and perceived barriers to PA of adolescent girls grouped by school grade and biological maturity status (i.e., early or late maturing) within grades. Methods: 221 girls (aged 8-16 years; grades 4-10) wore an Actical accelerometer for 7 days and then completed a semi-structured, open ended questionnaire on perceived barriers to PA over the 7 day period. Predicted APHV and recalled age at menarche were used to assess maturity among the elementary and high school girls, respectively. Maturity and grade group differences in PA were assessed using MANCOVA and independent sample t-test, and barriers to PA using chi squared statistics. Results: Daily minutes spent in MVPA decreased by 40% between grades 4 to 10. Within grade groupings, no differences in PA were found between early and late maturing girls (p>0.05). Grades 4-6 participants cited more interpersonal (i.e., social) barriers. Grades 9-10 participants cited more institutional barriers to PA, primarily revolving around the institution of school. No differences were found in types of barriers reported between early and late maturing girls. Conclusion: Since PA and types of perceived barriers to PA were dependent on grade, future research should work to identify the most salient (i.e., frequent and limiting) barriers to PA by chronological age in youth.<p> Study 3: Although the metabolic syndrome is thought to be mainly a consequence of obesity, the mechanisms underpinning its development are not that well understood. The purpose of study 3 was to examine total body fat mass (FM), trunk FM and PA developmental trajectories (aligned to BA; years from APHV) of individuals categorized as low and high for cardiometabolic risk at 26 years, while investigating biological and lifestyle risk factors. Methods: The sample were 55 males and 76 females from the Saskatchewan Pediatric Bone Mineral Accrual Study (1991-2007) who were assessed from childhood to young adulthood and had a measure of cardiometabolic risk at young adulthood (26.0 + 2.3 yrs). Height was measured biannually. Total body FM and trunk FM was assessed annually by dual energy-X-ray absorptiometry. PA and dietary intake was evaluated two to three times annually using surveys. Individuals were grouped into maturity status groups (early, average or late) depending on their APHV. Two composite cardiometabolic risk scores were calculated for males and females separately. The first was derived for a sub-sample (N=48) by summing the standardized residuals of inverted high-density lipoprotein cholesterol, homeostasis model assessment for insulin resistance, mean arterial pressure (MAP) and fasting triglyceride levels. A second score was derived for the whole sample by summing the standardized residuals for MAP. Scores for both samples were regressed on to age and adult smoking status. High and low cardiometabolic risk groups were determined based on a sex- specific median split of risk scores. Data were analyzed using random effects models. Models were built in a stepwise procedure with predictor variables added one at a time, using the log likelihood ratio statistic to determine if one model was a significant improvement over the previous one. Results: The final model indicated that once the independent effects of maturity (years from APHV) and height were controlled, the high risk group males and females had significantly (p<0.05) greater total body FM and trunk FM development at all ages. No association was found between young adult cardiometabolic risk and development of PA. Furthermore, in general, timing of biological maturity was not associated with development of PA or FM. Conclusion: Young adults at higher cardiometabolic risk have greater body fat as early as 8 years of age, which lends support to early intervention.<p> General Conclusions: Adolescence has been highlighted as a critical period for the development of adult disease, such as the metabolic syndrome. Results from this thesis support this contention by showing a decrease in PA (by both chronological and biological age) in males and females across adolescence. It further showed that an increase in total and central fatness during adolescence may be critical for the development of the metabolic syndrome in adulthood. Timing of biological maturity, in general, was not shown to have an independent impact on adolescent or young adult PA, adolescent perceived barriers to PA, fat mass development, or young adult cardiometabolic risk. However, further research is required before definitive conclusions can be made about the short and long term impacts of timing of biological maturity on health.

Adolescence is characterized by systematic and dramatic physical and behavioural changes, the most noticeable physical growth is the rapid increase in stature marked by peak height velocity (PHV). Anecdotally, many people are aware that as youth pass through their adolescent growth spurt there is a perceived period of physical awkwardness; however, there is no scientific agreement as to whether a period of awkwardness associated with the adolescent growth actually exists. Previous research has focused on the development of general motor performance or gross motor coordination. Increases in strength during adolescence may mask the effect of a stage of adolescent awkwardness on general motor performance tasks. To detect adolescent awkwardness it is necessary to measure either performance of skills that specifically do not depend on strength, or body awareness. The purpose of this study was to investigate whether female adolescents’ awareness of their body size and movement was influenced by biological maturation, and whether adolescent awkwardness could be detected in performance of sport specific skills independent of strength. An endpoint matching task was used to measure awareness of foot position in space by measuring the distance (mm) between a reference and matching endpoint position (endpoint matching error (EME)) with eyes either open or closed. The Johnson wall volley and a ball juggling task were used to measure soccer specific skill and coordination. Thirty six female youth soccer players, aged 10-14 years, were recruited. Age at PHV was predicted from measures of age, height, leg length and weight. Three groups were identified: pre-PHV (n=6), PHV (n=5) and post –PHV (n=25). Mean group differences were assessed using ANOVA. It was found that when the endpoint matching task was performed with eyes open there was no significant difference in mean EME between groups (p > 0.05). With eyes closed the PHV group performed worse than the pre-PHV and post-PHV groups. The Post-PHV group significantly (p < 0.05) decreased their EME (22.2 ± 13.9) compared to the PHV group (32.8 ± 17.6) but no difference was found with the Pre-PHV group (27.5 ± 15.7). On the wall volley test the Post-PHV group performed significantly (p < 0.05) better compared to the PHV group but not the Pre-PHV group. The Post-PHV group performed significantly (p < 0.05) better on the ball juggling task compared to both the Pre-PHV and the PHV groups. In conclusion, the results suggest that in the year around PHV body awareness, as measured by EME, may plateau or decrease and that soccer skill performance plateaus. This plateau or decrease in body awareness and soccer skills involving coordination is likely temporary; participants in this study who were > 6 months past PHV had significantly better body awareness and soccer skill performance than those participants who were within 6 months of PHV. The results from the endpoint matching task also indicate that a measure of body size and movement awareness has the potential to be used to measure changes in body awareness during the adolescent growth spurt. The results of this study suggest that teenage clumsiness could exists. However, a definitive study with larger maturity groups followed over time is required to confirm this statement.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-02-16T14:49:09Z No. of bitstreams: 1 phelipehenriquecardosodecastro.pdf: 1759606 bytes, checksum: 657f4b655e5a3a0d9a50918c0af70b6f (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-02-26T12:37:36Z (GMT) No. of bitstreams: 1 phelipehenriquecardosodecastro.pdf: 1759606 bytes, checksum: 657f4b655e5a3a0d9a50918c0af70b6f (MD5) / Made available in DSpace on 2016-02-26T12:37:36Z (GMT). No. of bitstreams: 1 phelipehenriquecardosodecastro.pdf: 1759606 bytes, checksum: 657f4b655e5a3a0d9a50918c0af70b6f (MD5) Previous issue date: 2014-04-16 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O conhecimento do perfil esportivo relacionado às variáveis antropométricas, físicas, psicológicas e maturacionais é de grande importância para treinadores terem parâmetros de avaliação e desenvolvimento do jovem atleta durante todo o processo de treinamento a longo prazo. Sabe-se que atletas de diferentes modalidades esportivas devem ser avaliados com testes específicos para a modalidade sendo que em relação ao atletismo não foram encontrados estudos que realizassem uma caracterização ampla dos jovens atletas pertencentes à categoria mirim. Desta forma, foram objetivos do estudo, descrever o perfil e elaborar uma tabela de percentil das variáveis morfológicas, psicológicas, físico/motoras, maturacionais e de provas específicas de atletas mirins masculinos de atletismo, verificar o efeito da maturação somática nas variáveis analisadas e a associação da avaliação do treinador em relação ao potencial de desempenho dos atletas com o ano de nascimento, estágio maturacional e vitórias em competições. Foram avaliados 94 jovens atletas de atletismo, de 8 equipes, pertencentes à categoria mirim. O protocolo foi desenvolvido em dois dias consecutivos. No primeiro dia, foi realizada a anamnese, antropometria (massa corporal, estatura, altura sentada, envergadura e dobras cutâneas), aplicação da escala de motivação para o esporte, teste anaeróbio Running-Based Anaerobic Sprint Test (RAST), prova do arremesso de peso, salto em distância, corrida de 800 m e um questionário para o treinador avaliar as características esportivas de cada atleta. No segundo dia, foi avaliada a flexibilidade (Sentar e Alcançar), impulsão vertical (Salto em Contra Movimento e Squat Jump), velocidade (Corrida de 60 m) e velocidade aeróbia máxima (Teste de Léger- Boucher). Após os testes, um pequeno questionário foi enviado aos pais biológicos para que os mesmos, auto-relatassem as respectivas estaturas. Os principais resultados encontrados foram: a definição das características dos jovens atletas de atletismo de acordo com as variáveis analisadas; a maturação somática influencia o comportamento das variáveis antropométricas (massa corporal, estatura, comprimento dos membros inferiores), físico/motoras (squat jump e salto em contra movimento); provas específicas (corrida de 60 m, arremesso do peso e salto em distância), mas por outro lado, não exerce influência na velocidade aeróbia máxima obtida no teste Léger-Boucher, no percentual de fadiga no RAST e no tempo da corrida de 800 m; a avaliação do potencial de desempenho dos atletas, feita pelo treinador, não está associada ao ano de nascimento ou ao estágio maturacional dos atletas, mas é influenciada pelo número de vitórias em competições. Pode-se concluir que jovens atletas de atletismo, pertencentes à categoria mirim, apresentam características específicas em relação às variáveis analisadas, sendo a maturação um fator interveniente nos resultados. Não existe associação entre o potencial de desempenho dos atletas, avaliados pelo treinador, com o ano de nascimento e estágio maturacional. Sendo que para a ocorrência de vitória em competições há associação. / The Knowledge of sports profile related to anthropometric, physical, psychological and maturity variables is of great importance for coaches have assessment parameters and development of young athletes throughout the process of long-term training. It is known that athletes from different sports should be evaluated By specific tests for the sport and in relation to track and field no studies that carried out an extensive characterization of young athletes belonging to the Mirim category were found. Thus, the objectives of study were to describe the profile and prepare a table of percentile of morphological, psychological, physical / motor, and maturity of specific evidence of male junior track and field athletes variables, evaluating the effect of somatic maturity in those variables and the association evaluation of the coach regarding the potential performance of athletes with year of birth, maturity stage and won competitions. 94 young track and field athletes of 8 teams, belonging to mirim category were evaluated. On the first day, was performed, anamnesis, anthropometric (weight, height, sitting height, arm span and skinfolds), applicated motivation scale for sport, Running-based Anaerobic Sprint Test (RAST) test was performed the shot put, long jump, 800 m run and questionnaire to evaluate the sports coach characteristics of each athlete. On the second day, we evaluated the flexibility (sit and reach), vertical jump (Jump Counter Movement and Squat Jump), Speed (60m run test) and maximal aerobic speed (Test Léger-Boucher). After testing, a short questionnaire was sent to the biological parents so that they selfreported the respective statures. The main findings were: defining the characteristics of young track and field athletes according to the variables analyzed, the somatic maturity influences the behavior of the anthropometric variables (weight, height, leg length), physical / motor (squat jump and countermovement jump), specific abilities (running 60 m, shot put and long jump), but on the other side, does not influence maximal aerobic speed obtained in Léger-Boucher test, the percentage of fatigue in RAST and run time of 800 m; evaluating the performance potential of athletes, taken by coach, is not associated with the year of birth or the maturity stage of the athletes, but is influenced by the number of victories in competitions. It Can be concluded that young track and field athletes, belonging to the Mirim category, has specific characteristics in terms of the variables analyzed, the maturity an intervening factor in the results. There is no association between the athlethes performance, measured by the coach, with birth year and maturity stage. On the other hand, there is association between occurrence of victory and competitions.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-05-09T17:46:15Z No. of bitstreams: 1 ramoncruz.pdf: 1157866 bytes, checksum: 0ae294ff6a73caf5150a4b6b96c5368f (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-06-10T12:00:31Z (GMT) No. of bitstreams: 1 ramoncruz.pdf: 1157866 bytes, checksum: 0ae294ff6a73caf5150a4b6b96c5368f (MD5) / Made available in DSpace on 2016-06-10T12:00:31Z (GMT). No. of bitstreams: 1 ramoncruz.pdf: 1157866 bytes, checksum: 0ae294ff6a73caf5150a4b6b96c5368f (MD5) Previous issue date: 2015-03-19 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O treinamento esportivo de jovens atletas precisa ser subsidiado por informações precisas e fidedignas sobre a intensidade dos treinamentos, estágio de maturação biológica e como diferentes grupos reagem aos estímulos de treinamento. Os objetivos do presente estudo foram: 1) Verificar se há associação entre o nível de desempenho esportivo, maturação biológica e o gênero na Percepção Subjetiva de Esforço (PSE) do treinamento; 2) Verificar se treinadores conseguem estimar com precisão a PSE dos atletas na sessões de treinamento. Participaram do estudo 75 atletas de atletismo, com idade de 14,4 ± 0,8 anos, massa corporal de 55,8 ± 11,7 kg e estatura de 165,6 ± 9,0 cm. Todos tinham, pelo menos, seis meses de prática de atletismo e a maior parte treinava de 5 a 6 vezes por semana. O protocolo experimental durou 7 dias consecutivos, os seguintes testes foram utilizados para avaliar o desempenho esportivo no primeiro dia: Corridas de 75, 250 e 1000 metros, salto em distância e arremesso do peso. 48 horas depois foram prescritas e acompanhadas 5 sessões de treinamento de atletismo, uma para cada teste de desempenho, com intervalo de 24 horas entre elas. O estágio de maturação biológica foi avaliado pelo método do percentual da estatura matura predita (% EMP). Não houve associação estatisticamente significativa entre o nível de desempenho esportivo e a PSE; não houve diferença da PSE entre os grupos normaturos e avançados (meninos) atrasados e normaturos (meninas). Meninas indicam maior valor de PSE nos treinos de 250 e 1000 metros, quando comparadas aos meninos. Não houve diferença na PSE dos atletas com a estimada pelos treinadores (meninos, meninas e grupo todo), entretanto, não ocorreu também a concordância relativa as intensidades leve, moderada e pesada. Não houve concordância entre as intensidades em cada sessão. Treinadores de atletismo subestimam a intensidade leve e superestimam as intensidades moderada e pesada, quanto as meninas tem maior dificuldade para estimar as cargas. Os resultados indicam que a PSE não é influenciada pelo nível de desempenho esportivo e estágio maturacional, em atividades com característica de resistências de velocidade e aeróbia meninas indicam maiores valores de PSE e os treinadores não conseguem estimar com precisão a PSE dos atletas nas sessões de treinamento. / The sports training of young athletes need to be subsidized by accurate and reliable information on the intensity of training, biological maturity stage and how different groups react to training stimuli. The objectives of this study were: 1) Verify if there is an association between the level of sports performance, biological maturity and gender in Rate Perceived Exertion (RPE) training; 2) Make sure coaches can accurately estimate the RPE of athletes in training sessions. The study enrolled 75 athletes from track and field, aged 14.4 ± 0.8 years, body weight 55.8 ± 11.7 kg and 165.6 ± 9.0 cm tall. All were at least six months track and field practice and most practiced 5 to 6 times per week. The experimental protocol lasted 7 consecutive days, the following tests were used to evaluate sports performance on the first day: 75 races, 250 and 1000 meters, long jump and shot put. 48 hours were prescribed and monitored 5 track and field training sessions, one for each performance test, with 24-hour interval between them. The biological maturity stage was evaluated by the percentage of the method of predicted mature height (% PMH). There was no statistically significant association between the level of sports performance and the RPE; there was no difference between the RPE normaturos and advanced groups (boys) and late normaturos (girls). Girls RPE indicate greater value in training of 250 and 1000 meters, compared to boys. No differences in RPE athletes with estimated by the coaches (boys, girls and whole group), however, did not also occur to agreement on the mild, moderate and heavy intensities. There was no agreement between the intensities at each session. Track and Field trainers underestimate and overestimate mild moderate and heavy intensities, the girls find it more difficult to estimate loads. The results indicate that the RPE is not influenced by the level of sports performance and maturity stage, in activities with characteristic speed of resistance and aerobic girls indicate higher RPE values and the coaches can not accurately estimate the RPE athletes in training sessions .

The study was a randomized clinical tria! involving two cohorts (12 and 18 months) of nutritionally at risk Jndonesian children and three types of supplementary feeding: high energy and micronutrients; skimmed milk and micronutrients; and skimmed milk. The hypothesis of the study was that high energy and micronutrient supplements given early to children could delay on physical growing and mental development. The results showed that a combined energy and micronutrient supplement given for ayear to the 12-month-old children had wide range beneficia! effects. The same supplement given to the 18-month-old had only a modest effect. This suggests that if such an intervention is to he effective it needs to begin early in life. / El estudio fue un ensayo clínico aleatorio en el que participaron dos cohortes de niños (12 y 18 meses) indonesios en riesgo nutricional; hubo tres suplementos dietéticos: energía alta y micronutrientes; leche descremada y micronutrientes; y leche descremada. Se puso a prueba la hipótesis de que un suplemento de energía y micronutrientes administrado tempranamente, previene el retardo en el crecimiento físico y el desarrollo mental. Se obtuvo que el efecto de la suplementación con energía y micronutrientes en los bebés de 12 meses fue superior al efecto producido por la suplementación con micronutrientes y leche descremada. Los efectos en el grupo que comenzó a los 18 meses fueron menores. Hubo una interacción entre los efectos. Los resultados sugieren que este tipo de intervención en niños desnutridos debe iniciarse durante el primer año de vida.