Effects of a 4-week high-intensity interval training on pacing during 5-km running trial

This study analyzed the influence of a 4-week high-intensity interval training on the pacing strategy adopted by runners during a 5-km running trial. Sixteen male recreational long-distance runners were randomly assigned to a control group (CON, n = 8) or a high-intensity interval training group (HIIT, n = 8). The HIIT group performed high-intensity interval-training twice per week, while the CON group maintained their regular training program. Before and after the training period, the runners performed an incremental exercise test to exhaustion to measure the onset of blood lactate accumulation, maximal oxygen uptake (VO2max), and peak treadmill speed (PTS). A submaximal constant-speed test to measure the running economy (RE) and a 5-km running trial on an outdoor track to establish pacing strategy and performance were also done. During the 5-km running trial, the rating of perceived exertion (RPE) and time to cover the 5-km trial (T5) were registered. After the training period, there were significant improvements in the HIIT group of ∼7 and 5% for RE (P = 0.012) and PTS (P=0.019), respectively. There was no significant difference between the groups for VO2max (P = 0.495) or onset of blood lactate accumulation (P = 0.101). No difference was found in the parameters measured during the 5-km trial before the training period between HIIT and CON (P \u3e 0.05). These findings suggest that 4 weeks of HIIT can improve some traditional physiological variables related to endurance performance (RE and PTS), but it does not alter the perception of effort, pacing strategy, or overall performance during a 5-km running trial

Efeito da adubação nitrogenada e do pastejo sobre a frequência de espécies invasoras em ambientes de pastagem cultivada.

Altas doses de nitrogênio e manejo do pastejo mais intensivo tendem a diminuir a freqüência de espécies invasoras, pelo favorecimento do crescimento da espécie principal e efeito do pastejo sobre a presença de espécies invasoras de potencial forrageiro

Prior Low- or High-Intensity Exercise Alters Pacing Strategy, Energy System Contribution and Performance during a 4-km Cycling Time Trial

We analyzed the influence of prior exercise designed to reduce predominantly muscle glycogen in either type I or II fibers on pacing and performance during a 4-km cycling time trial (TT). After preliminary and familiarization trials, in a randomized, repeated-measures crossover design, ten amateur cyclists performed: 1) an exercise designed to reduce glycogen of type I muscle fibers, followed by a 4-km TT (EX-FIB I); 2) an exercise designed to reduce glycogen of type II muscle fibers, followed by a 4-km TT (EX-FIB II) and; 3) a 4-km TT, without the prior exercise (CONT). the muscle-glycogen-reducing exercise in both EX-FIB I and EX-FIB II was performed in the evening, similar to 12 h before the 4-km TT. Performance time was increased and power output (PO) was reduced in EX-FIB I (432.8 +/- 8.3 s and 204.9 +/- 10.9 W) and EX-FIB II (428.7 +/- 6.7 s and 207.5 +/- 9.1 W) compared to CONT (420.8 +/- 6.4 s and 218.4 +/- 9.3 W; P0.05). the PO was lower in EX-FIB I than in CONT at the beginning and middle of the trial (P0.05). the integrated electromyography was unchanged between conditions (P>0.05). Performance may have been impaired in EX-FIB I due a more conservative pacing at the beginning and middle, which was associated with a reduced aerobic contribution. in turn, the PO profile adopted in EX-FIB II was also reduced throughout the trial, but the impairment in performance may be attributed to a reduced glycolytic contribution (i.e. reduced lactate accumulation).Foundation of Aids to Scientific Research of the State of Alagoas (FAPEAL)Univ Fed Pernambuco, CAV, Dept Phys Educ & Sports Sci, Sports Sci Res Grp, Vitoria de Santo Antao, Pernambuco, BrazilUniv São Paulo, Sch Phys Educ & Sport, Endurance Performance Res Grp, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Med, Div Nephrol, São Paulo, BrazilVictoria Univ, Coll Sport & Exercise Sci, Inst Sport Exercise & Active Living, Melbourne, Vic 8001, AustraliaUniversidade Federal de São Paulo, Dept Med, Div Nephrol, São Paulo, BrazilWeb of Scienc

Listening to Music in the First, but not the Last 1.5 km of a 5-km Running Trial Alters Pacing Strategy and Improves Performance

We examined the effects of listening to music on attentional focus, rating of perceived exertion (RPE), pacing strategy and performance during a simulated 5-km running race. 15 participants performed 2 controlled trials to establish their best baseline time, followed by 2 counterbalanced experimental trials during which they listened to music during the first (M-start) or the last (M-finish) 1.5 km. The mean running velocity during the first 1.5 km was significantly higher in M-start than in the fastest control condition (p < 0.05), but there was no difference in velocity between conditions during the last 1.5 km (p > 0.05). The faster first 1.5 m in M-start was accompanied by a reduction in associative thoughts compared with the fastest control condition. There were no significant differences in RPE between conditions (p > 0.05). These results suggest that listening to music at the beginning of a trial may draw the attentional focus away from internal sensations of fatigue to thoughts about the external environment. However, along with the reduction in associative thoughts and the increase in running velocity while listening to music, the RPE increased linearly and similarly under all conditions, suggesting that the change in velocity throughout the race may be to maintain the same rate of RPE increase.Australian Department of Education, Employment and Workplace RelationsAustralian Department of Education, Employment and Workplace Relation

Estabilidade e adaptabilidade da produtividade de feijão caupi no Estado do Tocantins.

O trabalho teve por objetivo avaliar a adaptabilidade e a estabilidade produtiva de genótipos de feijão-caupi no Estado do Tocantins. Os dados desse trabalho foram obtidos de quatro experimentos, conduzidos nas regiões norte e centro-sul do Estado do Tocantins. Foram observadas diferenças significativas na interação genótipo vs locais para a característica produtividade média de grãos (ton. ha-1), evidenciando a existência de variabilidade entre genótipos. A produtividade variou de 1.120,8 a 2.727,5 ton. ha-1, destacando-se como a mais produtiva a cultivar BRS-TUCUMAQUE.CONAC 2012. Disponível em: http://www.conac2012.org/resumos/pdf/233a.pdf. Acesso em: 07 ago. 2013

Entre o querer e o poder: dilemas da agricultura familiar nas trilhas de uma agricultura sustentável.

Resumo: A Embrapa Caprinos e o Banco do Nordeste firmaram convênio no período de dezembro/1999 à maio/2003 para execução do projeto de ?Validação e transferência de tecnologias para sistemas de produção de carne caprina e ovina em áreas de assentamento do Estado do Ceará?, com o objetivo de ?fortalecer sistemas de produção de caprinos e ovinos de áreas de assentamento do Estado do Ceará. Adotando postura metodológica recomendada por Bunch (1994), o projeto privilegiou a realização de experimentos em pequena, tendo em vista evitar riscos em grandes áreas de agricultores (as) que lidam com escassez de recursos em seus sistemas de produção. Assim, para alcançar os objetivos pretendidos e assegurar a continuidade das ações, o projeto teve início em fevereiro de 2000 com a preparação de 18 agricultores (as) multiplicadores (as) nos campos experimentais da Embrapa Caprinos. Em seguida, montou-se os experimentos em áreas coletivizadas de três assentamentos do Estado. Precedeu a implantação dos experimentos a realização de seminários-oficinas para escolha das tecnologias a serem validadas, de acordo com as expectativas dos assentados (as). A presente narrativa relaciona alguns resultados que apontam para ganhos na produção e na comercialização das produções de áreas de assentamento, mas, sobretudo, destaca as dificuldades que se interpõem nos passos a serem trilhados por unidades de produção familiar em busca de uma agricultura sustentável

Efeito do manejo nutricional de cabras leiteiras no início da lactação sobre a produção e os constituintes lácteos.

Resumo: Objetivou-se com este trabalho avaliar o efeito do manejo da alimentação de cabras leiteiras no início de lactação, sobre a produção e os constituintes lácteos. Utilizou-se dez cabras da raça Saanen com cinco dias de lactação, alojadas em baias coletivas. O experimento teve duração de quatro semanas, divididas em dois períodos de duas semanas cada. Foram avaliados a produção e os constituintes lácteos no início de lactação e a produção de leite durante o período experimental e toda a lactação. Os tratamentos consistiram de dois manejos para cabras no início de lactação. O primeiro com concentrado fixo em 400 g/kg de leite produzido e volumoso fornecido ad libitum, e o segundo com dieta completa com mínimo de fibra e consumo ad libitum. A produção média diária e total no início de lactação das cabras recebendo dietas completas foi superior à produção das cabras recebendo concentrado fixo. Por outro lado, não houve efeito dos tratamentos na produção de leite no período pós-experimental e durante toda a lactação. Também não houve efeito dos tratamentos sobre a composição do leite das cabras, mas houve uma redução nos teores dos constituintes nas últimas duas semanas da fase experimental. Nos dois tratamentos, houve uma depressão no teor de gordura. Dietas completas no início da lactação podem maximizar a produção de leite de cabras nesta fase; contudo, devem ser usadas estratégias de manejo ou aditivos para reduzir o impacto destas dietas sobre o teor de gordura no leite. [Effect of nutricional management in the early lactation on milk production and constituents of dairy]. Abstract: This experiment was carried out to evaluate the feeding management of dairy goats in the early lactation on milk production and constituents. Ten Saanen goats with five days milking were used. The experimental period was of four weeks, divided in two periods of two weeks each. The milk production and constituents in the early lactation and the milk production during the lactation were evaluated. The treatments consisted of two nutritional managements in the early lactation. The first one, was fixed concentrate in 400 g/kg of milk production and roughage ad libitum, and the second one was a total mixed ration offer with ad libitum consumption. Daily and total production in the early lactation of the goats fed total mixed rations was higher than the goats receiving fixed amounts of concentrate. On the other hand, it did not have effect of the treatments in the milk production in the post-experimental period. Also it did not have effect of the treatments on the milk goat composition, but it had a reduction in the last two weeks of the experimental period. In both treatments it was found milk fat depression. Total mixed rations in the early lactation can maximize the dairy goats production in this phase; however, strategies to reduce the impact of these diets on milk fat content should be use