Sleep impairment and altered pattern of circadian biomarkers during a long-term Antarctic summer camp.

Antarctic expeditions include isolation and exposure to cold and extreme photoperiods (with continuous natural light during summer) that may influence psychophysiological responses modulated by luminosity and sleep. We assessed changes in night sleep patterns by actigraphy, salivary biomarkers, and perceptual variables in seven participants in the following time points along a 50-day camping expedition in Antarctica (Nelson Island): Pre-Field (i.e., on the ship before camp), Field-1, Field-2, Field-3, Field-4 (from 1st to 10th, 11th to 20th, 21st to 35th and 36th to 50th days in camp, respectively), and Post-Field (on the ship after camp). We also characterized mood states, daytime sleepiness, and sleep quality by questionnaires. Staying in an Antarctic camp reduced sleep efficiency (5.2%) and increased the number of awakenings and wakefulness after sleep onset (51.8% and 67.1%, respectively). Furthermore, transient increases in time in bed (16.5%) and sleep onset latency (4.8 ± 4.0 min, from Pre- to Field-3) was observed. These changes were accompanied by an altered pattern of the emerging circadian marker ß-Arrestin-1 and a trend to reduce nocturnal melatonin [57.1%; P = 0.066, with large effect size (ES) from Pre-Field to Field-2 (ES = 1.2) and Field-3 (ES = 1.2)]. All changes returned to Pre-Field values during the Post-Field. The volunteers reported sleep-related physical complaints (feeling of cold and pain, discomfort to breathe, and cough or loud snoring), excessive daytime sleepiness, and reduced vigor during the camp. Thus, a 50-day camp alters neuroendocrine regulation and induces physical discomfort, which may explain the impaired sleep pattern and the consequent daytime sleepiness and mood changes.

Temporal response of post-activation performance enhancement induced by a plyometric conditioning activity.

Introduction: To better understand the post-activation performance enhancement (PAPE) effect promoted by a plyometric conditioning activity (CA), the aim of this study was to investigate the temporal response of PAPE after a plyometric CA. Methods: Fourteen healthy and active adults visited the laboratory 3 times, with an interval of 7 days between each visit. On the first day they were familiarized with the countermovement jump (CMJ) test and plyometric CA. In the second and third visits, participants performed either plyometric CA or control (remaining seated) in a crossover design. The CMJ test was performed pre and 1-, 3-, 6-, and 9-min post the plyometric CA or control. The comparisons were performed using the repeated measure two-factor ANOVA and Bonferroni adjustment (significance level adopted P ≤ 0.05). Results: Time (P < 0.01), condition (P < 0.01), and interaction (P < 0.01) effects were reported for CMJ comparisons. For the control condition, CMJ increased at 3 min compared to pre (P = 0.03) and at 3 min compared to 1 min (P = 0.03). For the plyometric CA, CMJ increased at 1- (P < 0.01), 3- (P < 0.01), and 6-min (P = 0.02) compared to pre. For condition comparisons, CMJ was different at 1- (P < 0.01), 3- (P < 0.01), 6- (P < 0.01), and 9-min (P = 0.02). The Effect size of the comparisons of all moments compared to pre was null (d < 0.20) for control and small (d < 0.50) for plyometric CA. Discussion: It is possible to conclude that the plyometric CA promoted a PAPE effect for up to 9-min. Strength and conditioning coaches and practitioners may consider multiple sets of plyometric CA to produce immediate enhancement of power in the lower limbs.

Exploring the Predeployment Phase of an Antarctic Expedition and the Brazilian Pre-Antarctic Training.

In Antarctica, human access and presence are complex and require detailed planning and preparation in advance. The personnel of National Antarctic Programs (NAPs, i.e., scientists and support personnel, including military, civilians, and mountaineers) stay in different isolation, confinement, and extreme (ICE) environments such as ships, research stations, and scientific summer camps. Antarctica imposes harsh conditions that influence physiological and psychological responses impacting health, mood, and physical and cognitive performances. In this context, we argue why people should prepare in advance for staying in Antarctica and what to expect in ICE environments. We also spotlighted recommendations shared by different NAPs participant guides, including predeployment training. Next, we present a case study of the Brazilian Pre-Antarctic Training (PAT), a theoretical-practical training that provides technical and logistical information and assesses the adaptability and physical capacity of researchers and military personnel to perform fundamental activities in a polar environment. We evaluated and compared the individual's mood at the beginning and the end of the PAT week and observed group-specific mood changes depending on the sex, functions, and the facilities that participants accessed. Finally, we proposed that conducting training before staying in Antarctica, besides promoting conditions to better plan the voyage and knowledge of the region, can contribute to dealing with the possible mood swings during expeditions and even promote positive affect. Therefore, the psychophysiological effects of PAT are topics for further investigations.

Aerobic Training Modulates the Increase in Plasma Concentrations of Cytokines in response to a Session of Exercise.

Acute physical exercise can modulate immune function. For example, acute exercise is known to increase the circulating concentration of cytokines. Exercise is also known to modulate immune function chronically. It is not known whether exercise training can result in training of the immune system. Here, we investigated the effects of six weeks of aerobic training on cytokine responses induced by acute exercise until fatigue. Twelve healthy men performed a fatiguing exercise at the anaerobic threshold (AT) intensity. After the training period, the participants performed another bout of acute exercise at the same duration and intensity of the pretraining situation. The analysis was made at the beginning, end, and at 10, 30, and 60 minutes during the recovery period. Training at AT induced a gain of 11.2% of exercise capacity. Before training, a single bout of acute exercise induced a significant increase in plasma levels of cytokines, including IL-6, TNF-α, sTNFR1, IL-10, CXCL10, BDNF, leptin, resistin, and adiponectin. After six weeks of aerobic training, levels of IL-6, sTNFR1, BDNF, and leptin increased to a lesser extent after an acute bout exercise at the same absolute intensity as the pretraining period. Responses to the same relative exercise intensity were similar to those observed before exercise. These results show that aerobic training is associated with training of acute immune responses to acute exercise until fatigue.

Official matches and training sessions: physiological demands of elite junior badminton players

Abstract Aim: To evaluate the intensity of training and official badminton matches (international championship) in junior elite players. Methods: Twelve elite players from the Brazilian junior national team (6 male and 6 female) were monitored during 19 training sessions and 50 official men's and women's single and double matches in the XXVII Pan-American Junior Games. Subjects underwent an incremental running step test to determine maximal oxygen uptake (VO2max), and an individual relationship between heart rate (HR) and VO2max was established to estimate exercise intensity and oxygen uptake at official matches (OMs) and training sessions. HR was monitored during multi-shuttlecock (MS), technical-tactical (TT), and physical (PS) training methods, as well as during simulated matches (SMs) and OMs. Variables such as %HRmax, HR zones, %VO2max, and energy expenditure were also calculated. Results: OM was the most intense activity monitored for male and female athletes, followed by SM according to %HRmax (86.8 ± 4.1% and 84.4 ± 5.0% for female and male, respectively, in OM vs. 74.6 ± 2.3% and 75.0 ± 5.0% for female and male, respectively, in SM). OM mean energy expenditure was 10.7 ± 0.5 kcal.min-1 for females and 14.9 ± 4.6 kcal.min−1 for males. Conclusion: MS training has less physiological demand and OM presented higher intensity. SM, on the other hand, had the closest physiological demand to an OM.

Effects of soccer training during preseason on physical and physiological variables in youth soccer players

Abstract Aim: This study aimed to explore the effects of a training program during the pre-season on aerobic and anaerobic performance, hemodynamics, autonomic variables, and sleep quality in youth soccer players. Methods: Nineteen athletes, with an average age of 17 ± 1 years, participated in the study. The multicomponent training protocol was divided into technical, tactical, and physical practice for four weeks. The cardiac autonomic modulation was obtained through an electrocardiogram and blood pressure values were measured by a sphygmomanometer. The athletes answered the Pittsburgh questionnaire that assessed sleep patterns and issues. The VO2max was analyzed using the Intermittent Recovery Test Yo-Yo level 1. The RAST test was used to assess anaerobic power. Results: There was improvement in Heart Rate Variability (HRV) indicated by the increase in indexes, mean square root of the differences between normal cycles (RMSSD), low frequency increase (LF) (p = 0.04; d = 0.70), high frequency decrease (HF) (p = 0.01; d = 1.02) and the LF / HF sympathovagal index (p = 0.03; d = 0.70), variables related to faster recovery. An improvement in the components of sleep duration (p = 0.03) and quality (p = 0.02) of baseline and post-intervention sleep was also observed. Conclusion: The four-week multicomponent protocol contributed to improving VO2max, improving fatigue rates, quality of sleep, and maximum power. Additionally, we observe that youth soccer athletes had physiological and hemodynamic adaptations that resulted in an improvement in cardiac autonomic modulation and sleep patterns after four weeks of training.

Thermoregulatory and metabolic responses to a half-marathon run in hot, humid conditions.

This study describes the thermoregulatory and metabolic responses during a simulated half-marathon (21 km) run performed outdoors in a hot, humid environment. Ten male runners were recruited for the study, The run was carried out individually under solar radiation on a predetermined path in the following environmental conditions (ambient temperature: 27.96 ± 1.70 °C, globe temperature: 28.52 ± 2.51 °C, relative humidity: 76.88 ± 7.49%, wet bulb globe temperature: 25.80 ± 1.18 °C). Core temperature, skin temperature, head temperature, heat storage, heart rate, expired gases, rating of perceived exertion, and speed were measured or calculated before the start, every 3 km, and immediately following the run. Comparisons were made for each dependent variable using one-way repeated measures analysis of variance tests, and a Bonferroni test. Average run time and pace were 101:00 ± 9:52 min and 4:48 ± 00:16 min km-1, respectively. Participants significantly reduced their running speed, oxygen consumption, and heat storage at 9 km (p < 0.05). While core temperature was significantly increased at 6 km (p < 0.05) before plateauing for the remainder of the run. The key finding was that most of the runners reduced their pace when a Tcore of 39 °C was reached which occurred between 6 and 9 km of the run, yet runners were able to increase their speed demonstrating an "end-spurt" near the end of the run.

Correlation between running asymmetry, mechanical efficiency, and performance during a 10 km run.

Running asymmetry is considered a matter of concern for performance and injury, but the association between asymmetry and performance remain unclear. There are different strategies to address asymmetries and its relationship with performance. Here we investigated the correlation between global symmetry index and mechanical efficiency during 10 km running. Thirteen amateur trained athletes (8 men and 5 women) performed a 10 km running at a fixed pace while a 3D accelerometer attached to the pelvic region recorded position data throughout the course of the run and gas exchanges were monitored breath by breath. Global symmetry index was determined for 3 directions, and mechanical efficiency was calculated as the ratio of external work output to energy expenditure determined from gas analysis. Global Symmetry Index and mechanical efficiency decreased (-55.5% and -44.8%, respectively) during the course of the 10 km run (p < 0.01). A positive correlation was observed between global symmetry index and efficiency (r = 0.66, p = 0.01). Asymmetry in the vertical direction had a relatively higher impact on the global symmetry index. The global symmetry index accounted for 43.1% of the variance in mechanical efficiency (p = 0.015). Symmetry, evaluated by the global symmetry index, directly correlates with mechanical efficiency during a 10 km run.

Mental fatigue does not affect heart rate recovery but impairs performance in handball players / Fadiga mental não altera a recuperação da frequência cardíaca, mas afeta o desempenho de jogadores de handebol / Fatiga mental no varía la reparación de frecuencia cardiaca y muda el rendimiento en balonmano

INTRODUCTION: This study involved an analysis of the impact of mental fatigue on heart rate recovery (HRR), subjective measures of fatigue and intermittent running performance in handball players. OBJECTIVE: This study was aimed at (1) examining the effects of an induced state of mental fatigue on the aerobic performance of handball players, as measured by the Yo-Yo IR1 test, and (2) exploring possible changes in heart rate regulation through HRR analysis. METHODS: Twelve handball players (age: 17.50 ± 3.63 years; 5 ± 2.2 years of practice) undertook a Yo-Yo IR1 test on two occasions, separated by an interval of at least 72 hours. The Yo-Yo IR1 test was preceded by a 30-min treatment, consisting of the Stroop Color-Word Test, to induce mental fatigue. Participants in the control condition watched an emotionally neutral video. RESULTS: Higher ratings of mental fatigue and mental effort following the Stroop Test were observed for the experimental group. No differences in motivation were observed between conditions. Moreover, the induction of mental fatigue impaired running performance and led to a higher RPE during the Yo-Yo IR1 test. Notwithstanding, no changes in HRR or blood lactate levels were observed across conditions. CONCLUSION: Altogether, these results suggest that mental fatigue impairs intermittent running performance, without affecting HRR values. Level of Evidence III; Case-Control study.

INTRODUÇÃO: Este estudo envolveu uma análise do impacto da fadiga mental sobre a recuperação da frequência cardíaca (RFC), medidas subjetivas de fadiga e desempenho de corrida intermitente em jogadores de handebol. OBJETIVO: Este estudo visou (1) examinar os efeitos de um estado induzido de fadiga mental no desempenho aeróbico de jogadores de handebol, medido pelo teste Yo-Yo IR1 e (2) explorar possíveis alterações na regulação da frequência cardíaca através da análise da RFC. MÉTODOS: Doze jogadores de handebol (idade: 17,50 ± 3,63 anos, 5 ± 2,2 anos de prática) realizaram um teste Yo-Yo IR1 em duas ocasiões, com pelo menos 72 horas de intervalo. O teste Yo-Yo IR1 foi precedido por tratamento de 30 minutos que consistiu no teste Stroop Color-Word para induzir estado de fadiga mental. Os participantes na condição de controle assistiram a um vídeo emocionalmente neutro. RESULTADOS: Foram observadas taxas mais elevadas de fadiga mental e esforço mental após o teste Stroop para o grupo experimental. Não foram observadas diferenças na motivação entre as condições. Além disso, a indução de fadiga mental prejudicou o desempenho de corrida e levou a maior PSE durante o teste Yo-Yo IR1. Não obstante, não foram observadas alterações na RFC nem nas concentrações de lactato sanguíneo entre as condições. CONCLUSÃO: Em conjunto, esses resultados sugerem que a fadiga mental afeta o desempenho de corrida intermitente, sem alterar os valores de RFC. Nível de Evidência III; Estudo de caso-controle.

INTRODUCCIÓN: En el presente estudio se analizó el impacto de la fatiga mental en la recuperación de la frecuencia cardíaca (RFC), las medidas subjetivas de fatiga y el rendimiento intermitente en atletas de handball. OBJETIVO: los objetivos de este estudio fueron (1) examinar los efectos de un estado inducido de fatiga mental en el rendimiento aeróbico de atletas de handball, medida por el Yo-Yo IR1, y (2) explorar las posibles alteraciones en la regulación de la frecuencia cardíaca a través del análisis RFC. MÉTODOS: Doce atletas (edad: 17,50 ± 3,63 años, 5 ± 2,2 años de práctica) realizaron un test Yo-Yo IR1 en dos ocasiones, separados por un intervalo de al menos 72 horas. El test Yo-Yo IR1 fue precedido por un tratamiento de 30 minutos, consistente en el Stroop Color-Word Test, para inducir un estado de fatiga mental. Los participantes en la condición de control asistieron un video emocionalmente neutro. RESULTADOS: Se observaron altas percepciones de fatiga y esfuerzo mental después del test de Stroop para el grupo experimental. No se observaron diferencias de motivación entre las condiciones. Además, la inducción de fatiga mental perjudicó el desempeño de carrera y llevó a un mayor PSE durante el test Yo-Yo IR1. No obstante, no se observaron alteraciones en la RFC y en las concentraciones de lactato sanguíneo entre las condiciones. CONCLUSIÓN: En conjunto, estos resultados sugieren que la fatiga mental afecta el rendimiento intermitente de la carrera, sin alterar los valores de FCR. Nivel de Evidencia III; Estudio de caso-control.

Mental Fatigue Impairs Physical Performance in Young Swimmers.

PURPOSE: This study aimed to investigate the impact of mental fatigue on heart rate variability, subjective measures of fatigue, and swimming performance in young athletes. METHODS: Sixteen swimmers [15.45 (0.51) y old, 7.35 (2.20) y of swimming experience] performed a 1500-m time trial on 2 occasions separated by an interval of at least 72 hours. The 1500-m swimming was preceded by a 30-minute treatment that consisted of performing the Stroop Color and Word test to induce mental fatigue (experimental trial) or watching an emotionally neutral video (control trial). RESULTS: Participants reported higher ratings of mental fatigue and mental effort following the Stroop test when compared with the control trial, but no differences in motivation were observed. The induction of mental fatigue impaired swimming performance, as evidenced by a slower time (1.2%) to complete the 1500-m trial. No intertrial differences were identified for rating of perceived exertion during the swimming test or in heart rate variability after the Stroop and swimming tests. CONCLUSION: The results indicate that induction of mental fatigue impairs 1500-m swimming performance without changing heart rate variability.

A prior isometric strength training increases muscle power performance of judo athletes / Exercício preparatório de força isométrico aumenta o desempenho de potência muscular de judocas

ABSTRACT Muscular power, a determinant in judo fights, can be developed by high intensity strength exercises through a mechanism known as post-activation potentiation. Thus, the objective of the present study is to verify the effect of isometric squat exercise on the performance of judo athletes. The sample was made up of eight judo athletes (22.3 ± 3.5 years old, 166.0 ± 6.0 cm; 65.4 ± 7.0 kg). The subjects went through four days of tests, one familiarization session, another as a control situation and two others as experimental sessions. In the experimental sessions, exercises in a Smith squat machine prior to the vertical countermovement jump (CMJ) test and a Special Judo Fitness Test (SJFT). In the control session, only SJFT was performed. Student's t test for paired samples was used to compare performances in the different situations. A significant increase was observed in the number of projections in the SJFT (25.5 ± 2.2 vs. 26.8 ± 2.2 projections) after MVIC and in the height in CMJ (31.0 ± 2.2 vs. 33.3 ± 2.2 cm). The MVIC exercise protocol performed as a preparatory activity increased the performance of judo athletes in judo-specific tests/SJFT and CMJ.

RESUMO A potência muscular, determinante nas lutas de judô, pode ser desenvolvida por exercícios de força de alta intensidade através de um mecanismo conhecido como potenciação pós-ativação. Sendo assim, o objetivo do presente estudo é verificar o efeito do agachamento em isometria no desempenho de judocas. A amostra foi composta por oito judocas (22,3 ± 3,5 anos; 166,0 ± 6,0 cm; 65,4 ± 7,0 kg). Foi realizado quatro dias de testes, uma para sessão de familiarização, uma para a situação controle e duas para sessões experimentais. Nas sessões experimentais foi testado o efeito do exercício de agachamento guiado em contração voluntária isométrica máxima (CVIM) no desempenho do Special Judo Fitness test (SJFT) e do salto vertical com contra movimento (SCM). Na sessão controle foi realizado apenas o SJFT. O teste T Student pareado foi utilizado para comparar o desempenho entre as diferentes situações. Após a execução da CVIM foi observado um aumento significativo no número de arremessos no teste SJFT (25,5±2,2 vs. 26,8±2,2 projeções) e na altura do SCM (31,0 ± 2,2 vs. 33,3±2,2 cm). O protocolo de exercício CVIM realizado como atividade preparatória aumentou o desempenho de atletas de judô em teste específicos do Judô / SJFT e de SCM.

Limiar anaeróbico de 4 mM é capaz de estimar a máxima fase estável de lactato de jogadores de futebol em testes de campo / Anaerobic threshold of 4.0mM is able to estimate the maximal lactate steady state of soccer players on the field tests

Diante à importância da capacidade aeróbia para o desempenho de jogadores de futebol, o Limiar Anaeróbio tem sido um parâmetro comumente utilizado para a avaliação desses atletas. Todavia, faltam informações a respeito da validade dos protocolos de campo adotados no meio futebolístico. Portanto, o objetivo do presente estudo foi comparar os valores de velocidade de corrida (VC) e frequência cardíaca (FC) associados à máxima fase estável de lactato (MFEL) e limiar anaeróbico de 4,0mM (OBLA), e verificar se uma concentração fixa de lactato de 4 mM pode ser utilizada para estimar a MFEL em jogadores de futebol em testes de campo. Para tanto 22 jogadores de futebol da categoria sub 20 anos (18,1 ± 0,2 anos) foram avaliados. O OBLA foi considerado como a VC correspondente a lactatemia de 4,0mM e a MFEL foi determinada por meio de exercícios submáximos de intensidade constante com duração de 30 minutos. Os resultados não demonstraram diferenças significativas entre VC e FC identificadas pela MFEL e OBLA e apresentaram correlação significativa entre VC identificada pela MFEL e OBLA (r=0,56; p<0,01). Conclui-se que a concentração fixa de lactato 4mM (OBLA) pode ser utilizada para estimar a VC associada à MFEL em jogadores de futebol em testes de campo. A FC deve ver utilizada com cautela quanto aplicada isoladamente para controle de intensidade.(AU)

Given the importance of aerobic capacity for the performance of soccer players, the Anaerobic Threshold has been a commonly parameter used to assess these athletes. However, there is missing information about the validity of field protocols adopted in the soccer environment. Therefore, the aim of this study was to compare the values of running speed (RS) and heart rate (HR) associated with the maximal lactate steady state (MLSS) and anaerobic threshold of 4.0mM (OBLA), and identify whether a fixed lactate concentration of 4 mM can be used to estimate the MLSS in soccer players in field tests. Twenty two soccer players of under 20 (18.1 ± 0.2 years) were evaluated. OBLA was taken as the RS corresponding to blood lactate concentration of 4.0 mM and MLSS was determined by sub maximal constant intensity exercise with a duration of 30 minutes. The results showed no significant differences between RS and HR identified by the MLSS and OBLA and showed significant correlation between the RS identified by MLSS and OBLA (r=0.56, p< 0.01). It is concluded that fixed concentration of 4 mM lactate (OBLA) can be used to estimate the RS associated with MLSS in soccer players in field tests. HR should be used with caution when applied separately for intensity control.(AU)

Maximal power output estimates the MLSS before and after aerobic training / Potência máxima estima a MFEL antes e após o treinamento aeróbio / Potencia máxima estima el MLSS antes y después del entrenamiento aerobio

The purpose of this study is to present an equation to predict the maximal lactate steady state (MLSS) through a VO2peak incremental protocol. Twenty-six physically active men were divided in two groups (G1 and G2). They performed one maximal incremental test to determine their VO2peak and maximal power output (Wpeak), and also several constant intensity tests to determine MLSS intensity (MLSSw) on a cycle ergometer. Group G2 underwent six weeks of aerobic training at MLSSw. A regression equation was created using G1 subjects Wpeak and MLSSw to estimate the MLSS intensity (MLSSweq) before and after training for G2 (MLSSweq = 0.866 x Wpeak-41.734). The mean values were not different (150±27W vs 148±27W, before training / 171±26W vs 177±24W, after training) and significant correlations were found between the measured and the estimated MLSSw before (r²=0.49) and after training (r²=0.62) in G2. The proposed equation was effective to estimate the MLSS intensity before and after aerobic training...

Este estudo propõe uma equação para predição da máxima fase estável de lactato (MFEL) através de um teste para medida do VO2pico. Vinte e seis homens fisicamente ativos foram divididos em dois grupos (G1 e G2). Eles realizaram um teste máximo para medida do VO2pico e potência máxima (Ppico) e testes submáximos para determinar a intensidade da MFEL (MFELw) em cicloergômetro. O grupo G2 treinou por seis semanas na MFELw. Uma equação de regressão linear foi desenvolvida utilizando os resultados do G1 (Ppico e MFELw) para estimativa da MFEL (MFELweq) antes e após o treinamento no G2 (MFELweq=0,866 x Ppico-41,734). Os valores médios não foram diferentes (150±27W vs 148±27W, pré-treino / 171±26W vs 177±24W, pós-treino) e encontrou-se uma correlação significativa entre a MFELw medida e estimada antes (r²=0,49) e após o treinamento (r²=0,62) no grupo G2. A equação proposta foi efetiva para estimar a MFEL antes e após o treinamento...

Este estudio propone una ecuación para la predicción del máximo estado estable de lactato (MLSS) a través de un test para medir VO2pico. Veintiséis hombres físicamente activos se dividieron en dos grupos (G1 y G2). Ellos realizaron un test máximo para medir el VO2pico y potencia máxima (Ppico) y testes submáximas para determinar la intensidad de la MLSS (MLSSw) en cicloergómetro. El grupo G2 entrenó por seis semanas en la MLSSw. Una ecuación de regresión lineal fue desarrollada utilizando los resultados del G1 (Ppico y MLSSw) para estimar la MLSS (MLSSweq) antes y después del entrenamiento en el G2 (MFELweq=0,866 x Ppico-41,734). Los valores medios no fueron distintos (150±27W vs 148±27W, pre-entrenamiento / 171±26W vs 177±24W, después del entrenamiento) y se encontró una correlación significativa entre la MFELw medida y estimada antes (r²=0,49) y después del entrenamiento (r²=0,62) en el G2. La ecuación propuesta fue eficaz para estimar la MLSS antes y después del entrenamiento...

Efeitos do calor no OBLA: comparação entre ambiente quente e temperado / Effects of heat on OBLA: comparison between warm and temperate environments

O OBLA (onset of blood lactate accumulation) é um método utilizado para estimar o limiar de lactato (LL). Entretanto, ainda não está claro o efeito da temperatura ambiente sobre o OBLA. O objetivo do presente estudo foi comparar o OBLA em ambiente quente (40ºC) e temperado (22ºC). Nove homens (idade: 23,9±2,4 anos; massa corporal: 75,9±7,3 kg e VO2máx: 47,8±4,9 mL•kg-1•min-1) realizaram teste progressivo em cicloergômetro para determinação da potência máxima (Wmáx) e do OBLA nos dois ambientes. A Wmáx (195±25W vs 225±28W) e a potência no OBLA (153±30W vs 165±32W) foram menores no ambiente quente do que no temperado. A frequência cardíaca no OBLA-40 foi maior do que no OBLA-22 (171±8 vs 153±10 bpm, respectivamente). Não foi observada diferença no consumo de oxigênio no OBLA-22 e OBLA-40 (31,65±5,21 vs 31,12±6,82 mL•kg-1•min-1). Estes resultados indicam que as condições ambientais influenciam a determinação do OBLA.

The OBLA (onset of blood lactate accumulation), is a method used to estimate the lactate threshold (LT). However, It is unclear the effect of ambient temperature on OBLA. The aim of this study was to compare OBLA determined in warm (40°C) and temperate (22ºC) environments. Nine men (age: 23.9±2.4 years, body mass: 75.9±7.3kg and VO2máx: 47.8±4.9 mL•kg-1•min-1) performed an incremental test in cycle ergometer to determine the maximal power output (Wmax) and OBLA in the heat (OBLA-40) and temperate (OBLA-22) environments. The Wmax (195±25W vs 225±28W) and the power output associated with the OBLA (153±30 W vs 165±32W) were lower in warm than in temperate experiments. The heart rate at OBLA-40 was higher than in OBLA-22 (171±8 vs 153±10 bpm, respectively). No difference was found in oxygen uptake at OBLA-22 and OBLA-40 (31.65±5.21 vs 31.12±6.82 mL•kg-1•min-1). The results indicate that environmental conditions influence the OBLA determination.

Six weeks of aerobic training improves VO2max and MLSS but does not improve the time to fatigue at the MLSS.

The purpose of this study was to investigate the effects of a 6-week aerobic training period on the time to fatigue (t lim) during exercise performed at the maximal lactate steady state (MLSS). Thirteen untrained male subjects (TG; age 22.5 ± 2.4 years, body mass 72.9 ± 6.7 kg and VO2max 44.9 ± 4.8 mL kg(-1) min(-1)) performed a cycle ergometer test until fatigue at the MLSS power output before and after 6 weeks of aerobic training. A group of eight control subjects (CG; age 25.1 ± 2.4 years, body mass 70.1 ± 9.8 kg and VO2max 45.2 ± 4.1 mL kg(-1) min(-1)) also performed the two tests but did not train during the 6-week period. There were no differences between the groups with respect to the VO2max or MLSS power output (MLSSw) before the treatment period. The VO2max and the MLSSw of the TG increased by 11.2 ± 7.2 % (pre-treatment = 44.9 ± 4.8 vs. post-treatment = 49.8 ± 4.5 mL kg(-1) min(-1)) and 14.7 ± 8.9 % (pre-treatment = 150 ± 27 vs. post-treatment = 171 ± 26 W), respectively, after 6 weeks of training. The results of the CG were unchanged. There were no differences in t lim between the groups or within groups before and after training. Six weeks of aerobic training increases MLSSw and VO2max, but it does not alter the t lim at the MLSS.

Correlação entre o desempenho de jogadores de futebol no teste de sprint de 30m e no teste de salto vertical / Correlation between performance of soccer players in the 30-meter sprint test and in the vertical jump test

O objetivo do estudo foi determinar o nível de correlação entre o desempenho nos 10m iniciais, dos 20m finais e no tempo total do teste de sprint de 30m, com o do salto vertical com contra-movimento (CMJ) entre jogadores de futebol. Participaram do estudo 167 jogadores das categorias profissional (N. 94) e júnior (N. 73). Foram determinadas as velocidades dos jogadores em 10m (V10), 20m (V20) e no total de 30m (V30). A habilidade de salto foi avaliada através do CMJ. Para correlacionar os dados, foi utilizado o coeficiente de correlação de Pearson com nível de significância de p<0,05. A categoria júnior apresentou maiores valores de V10 e menores valores de V20 em comparação com a categoria profissional (p<0,05). Os valores de correlação entre o CMJ e os parâmetros de velocidade para a categoria júnior foram; r= 0,239, 0,370, 0,408 para V10, V20 e V30 respectivamente e para a categoria profissional foram; r= 0,381, 0,381 e 0,470 para V10, V20 e V30 respectivamente. Quando as duas categorias foram avaliadas em conjunto os valores de correlação foram; r= 0,293, 0,386 e 0,441 para V10, V20 e V30 respectivamente. Foi encontrada uma fraca correlação entre o CMJ e o V10 da categoria júnior sendo a mesma moderada para os demais parâmetros. A categoria profissional apresentou valores de correlação moderada entre o CMJ e todos os outros parâmetros. Maiores valores de correlação do V10 para a categoria profissional pode ser devido a efeitos específicos do treinamento.

The aim of the present study was to determine the association between the results in the counter movement jump (CMJ) and the results in the first 10 meters, in the final 20 meters and the in the total 30 meters of a 30-meter sprint. One-hundred and sixty seven Soccer players from the professional (N. 93) and under twenty (N. 74) categories, from a Brazilian first division Soccer club participated in the study. The sprint test consisted of a 30-meter run timed at the 10-meter and at the 30-meter marks. The jump capacity was assessed through the CMJ. Pearson’s correlation (r) was used to determine the association between these variables. The significance level adopted was p<.05. The U-20 players presented faster V10 and slower V20 than the professionals (p<.05). The correlation (r) between CMJ and V10, V20 and V30 were .239, .370 and .408, respectively, for the U20 group and .381, .381 and .470, respectively, for the professional group. Evaluating the two categories together the correlation were; r= 0,293, 0,386 and 0,441 to V10, V20 and V30 respectively. The correlation between CMJ and V10 was weak and moderate for V20 and V30. In the professional category the correlation between CMJ and all the other parameters was moderate. It is probable that higher correlation values for CMJ and V10 for the professionals could be attributed to specific training effects.