The Tumor Microenvironment: The Making of a Paradigm

What has been will be again, what has been done will be done again; there is nothing new under the su

Yo-Yo IR2 test e teste de margaria: validade, confiabilidade e obtenção da frequência cardíaca máxima em jogadores jovens de futebol

Os objetivos do presente estudo foram: i) avaliar a validade de constructo do Yo-Yo Intermittente Recovery Test Level 2 (Yo-Yo IR2) e do teste de Margaria (TM) com o desempenho em alta intensidade de exercício durante jogos oficiais em jogadores de futebol; ii) verificar a confiabilidade (teste-reteste) dos dois testes; iii) comparar os valores da frequência cardíaca máxima (FCM) obtida nesses protocolos e em jogo. Dezoito jogadores (média ± DP; idade 14 ± 0,8 anos, estatura 172 ± 9cm, peso 64,3 ± 8,5kg) pertencentes à mesma equipe foram avaliados em teste-reteste nos referidos protocolos e no percentual de tempo de permanência acima de 85% da FCM individual (PTP>85%FCM) em dois jogos oficiais do Campeonato Mineiro Infantil. Uma alta correlação foi encontrada entre o desempenho no Yo-Yo IR2 e PTP>85%FCM (rs = 0,71; p 85%FCM (rs = 0,44; p = 0,06). O Yo-Yo IR2 se mostrou mais variável e menos reprodutível (CV = 11%; CCI [95% IC] = 0,38) do que TM (CV = 1%; CCI [95% IC] = 0,93). O maior valor de FCM (p < 0,001) ocorreu no jogo (202 ± 8bpm). A FCM no Yo-Yo IR2 (194 ± 4bpm) foi menor (p < 0,006) do que TM (197 ± 6bpm). Conclui-se que o Yo-Yo IR2 pode ser considerado mais válido para predizer a manutenção de alta intensidade de exercício em jogo que é uma importante medida de desempenho no futebol. Porém, há necessidade de padronização rigorosa entre os procedimentos de avaliação para estabilidade da medida. A FCM deve ser observada em diversas situações, principalmente competitiva, para possibilitar que ocorra o maior valor individual

Relationship among explosive power, body fat, fat free mass and pubertal development in youth soccer players: a preliminary study

Purpose: Changes in body size and functional capacities are highly individual during puberty, and the performance of a soccer player is often closely related to their maturity status. The aim of the study was to evaluate the relationships among explosive power, body fat, fat free mass and pubertal development in young soccer players. Methods: Explosive power (countermovement jump-CMJ), body mass index (BMI), percentage of body fat (¿), fat free mass (FFM) and a Self-Administered Rating Scale for pubertal development (PDS) values of 11 "Giovanissimi" (age 13 year), 13 "Allievi" (age 15 year) and 10 "Juniores" (age >17 year) male soccer players were compared. The statistical analysis was performed using an analysis of variance among categories with Fisher's post hoc as appropriate. Furthermore, Pearson correlations among variables were calculated considering all subjects and also within categories. Results: Statistical differences emerged among categories in CMJ (F (2,30) = 28.3, p < 0.01), body fat weight (F (2,31) = 29.2, p < 0.01) and PDS (F (2,29) = 18.5, p < 0.01), while ¿ values showed statistical differences only for "Giovanissimi" and "Juniores" (F (2,31) = 3.4, p = 0.01). CMJ showed significant correlations with FFM (r = 0.68) and PDS (r = 0.63), PDS with FFM (r = 0.66) and BMI with ¿ (r = 0.71) and FFM (r = 0.71). A high correlation was found within categories. Conclusion: Since we found differences between categories and no correlation between chronological age and pubertal status, this study highlights the importance of assessing of puberty in youth soccer team

Characteristics and effect of 8-week soccer training on lactate minimum speed

Purpose: This study aimed to (1) characterize 8 weeks of specific soccer training according to heart rate (HR) zones and speed zones, and (2) verify the effects of 8 weeks of specific soccer training on lactate minimum speed (LMS), and the respective HR (HRLMS) of professional soccer players. Methods: Fourteen professional soccer players (23 [3] years old, 78.4 [7.0] kg, and 6.9 [2.4] % body fat; second national division) underwent a lactate minimum test at two different moments, before and after 8 weeks of specific training. The training was characterized according to time spent at each heart rate zone, and in different speed zones. The comparison between LMS and HRLMS was performed using the Wilcoxon test. An effect-size qualitative analysis was also performed. Results: The training was performed predominantly in zone 1 (<80 % of maximal HR). The time spent at velocities below mean LMS was predominant. The LMS (pre: 10.9 [0.8] km h−1; post: 11.8 [0.7] km h−1), and its corresponding heart rate (pre: 161 [7.0] bpm; post: 163 [9.0] bpm) did not differ significantly between pre and post-training. However, the effect size analysis showed a moderate effect on LMS. Conclusion: Eight weeks of soccer training slightly increased LMS, without changing HRMLS. Since LMS heart rate does not change with training, it can be used as a boundary of soccer training intensity (i.e., above or below anaerobic threshold).Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Graduate Program in Movement Science São Paulo State UniversityDepartment of Physical Education Federal University of PernambucoDepartment of Physical Education São Paulo State UniversityNucleus of High Performance in SportDepartment of Physical Education Alagoas Federal UniversitySchool of Physical Education and Sport, Avenida Bandeirantes, 3900, Vila Monte AlegreNove de Julho UniversityGraduate Program in Movement Science São Paulo State UniversityDepartment of Physical Education São Paulo State UniversityFAPESP: 2013/15322-31CNPq: 401676/2014-