Reliability and Validity of Tethered Swimming Lactate Minimum Test and Their Relationship With Performance in Young Swimmers.

PURPOSE: To test the reliability and validity of tethered swimming lactate minimum test in young swimmers. METHODS: Lactate minimum test was performed twice to test the reliability (experiment 1; n = 13). In addition, the validity was investigated through lactate minimum test relationships with tethered swimming lactate threshold and peak force obtained during graded exercise test (experiment 2; n = 11). Finally, the correlations with mean speeds observed during 200-m (s200m) and 30-minute continuous efforts (s30min) were also analyzed (experiment 3; n = 15). In all experiments, the lactate minimum test began with 3-minute all-out effort to induce lactatemia, followed by an exhaustive graded exercise test. RESULTS: The lactate minimum intensity and mean force during the entire 3-minute all-out effort (MF) showed high reliability (coefficient of variation < 8.9% and intraclass correlation coefficient > .93). The lactate minimum intensity was not different compared with lactate threshold (P = .22), presenting high correlations (r = .92) and agreement (95% limits of agreement = ±7.9 N). The mean force during the entire 3-minute all-out effort was similar to peak force obtained during graded exercise test (P = .41), presenting significant correlations (r = .88) and high indices of agreement (95% limits of agreement = ±11.3 N). In addition, lactate minimum test parameters correlated both with mean speeds observed during 200-m (r > .74) and 30-minute continuous efforts (r > .70). CONCLUSION: Thus, tethered swimming lactate minimum test can be used for training recommendations and to monitor aerobic adaptations in young swimmers.

Acute Oxidative Effect and Muscle Damage after a Maximum 4 Min Test in High Performance Athletes.

The purpose of this investigation was to determine lipid peroxidation markers, physiological stress and muscle damage in elite kayakers in response to a maximum 4-min kayak ergometer test (KE test), and possible correlations with individual 1000m kayaking performances. The sample consisted of twenty-three adult male and nine adult female elite kayakers, with more than three years' experience in international events, who voluntarily took part in this study. The subjects performed a 10-min warm-up, followed by a 2-min passive interval, before starting the test itself, which consisted of a maximum 4-min work paddling on an ergometer; right after the end of the test, an 8 ml blood sample was collected for analysis. 72 hours after the test, all athletes took part in an official race, when then it was possible to check their performance in the on site K1 1000m test (P1000m). The results showed that all lipoproteins and hematological parameters tested presented a significant difference (p≤0.05) after exercise for both genders. In addition, parameters related to muscle damage such as lactate dehydrogenase (LDH) and creatine kinase (CK) presented significant differences after stress. Uric acid presented an inverse correlation with the performance (r = -0.76), while CK presented a positive correlation (r = 0.46) with it. Based on these results, it was possible to verify muscle damage and the level of oxidative stress caused by indoor training with specific ergometers for speed kayaking, highlighting the importance of analyzing and getting to know the physiological responses to this type of training, in order to provide information to coaches and optimize athletic performance.

Efeitos do exercicio agudo sobre biomarcadores sericos de ratos diabeticos / The effects of acute exercise on serum biomarkers in diabetics rats / Efectos del ejercicio agudo sobre biomarcadores de suero em ratones diabeticos

INTRODUÇÃO: As respostas ao exercício agudo dos biomarcadores, como a fosfatase alcalina (FA) e a creatina quinase (CK) séricas têm sido pouco investigadas em ratos diabéticos. OBJETIVOS: Verificar os efeitos do exercício físico aeróbio agudo sobre as concentrações de CK e FA, bem como, avaliar o estado hídrico em ratos diabéticos experimentais. MATERIAIS E MÉTODOS Foram utilizados ratos Wistar machos, adultos jovens, distribuídos em dois grupos: diabéticos (DA) e controles (CA). O diabetes foi induzido por meio da administração de aloxana monoidratado Sigma(r) (32 mg/kg de peso corporal). Duas semanas após confirmação do diabetes, ambos os grupos foram submetidos a uma sessão aguda de natação por 30 min, com carga aeróbia (4,5 % do peso corporal). Foram avaliados: glicose, hematócrito, CK, FA, albumina e a cinética de lactato durante o exercício por meio de coletas 25 µL de sangue da cauda dos animais, nos minutos 0, 10, 20 e 30 de exercício. RESULTADOS: ANOVA de dois fatores para medidas repetidas e o teste post hoc de Tukey apontaram diminuição significativa dos valores de glicemia após o exercício para o grupo DA, aumento significativo de CK pós-exercício para o grupo DA, aumento significativo de hematócrito para ambos os grupos após exercício e manutenção da FA após exercício para o grupo DA. CONCLUSÃO: O exercício agudo aeróbio foi eficiente no controle dos níveis glicêmicos de ratos diabéticos. Entretanto, deve ser aplicado com cautela, pois induziu altos valores de CK, sugerindo possíveis lesões teciduais. .

INTRODUCTION: The responses to acute exercise on biomarkers, such as alkaline phosphatase (ALP) and creatine kinase (CK) serum levels have been little investigated in diabetic rats. OBJECTIVES: To investigate the effects of acute aerobic exercise on the concentrations of CK and ALP as well as evaluating the hydration status in diabetic rats. MATERIALS AND METHODS: Were used male Wistar rats, young adults, divided into two groups: diabetic (DA) and controls (CA). The diabetes was induced in the rats by administration of alloxan monohydrate Sigma(r) (32 mg/kg body weight). Two weeks after confirmation of diabetes, both groups were subjected to an acute swim session for 30 min, with aerobic load (4.5% body weight). Glucose, hematocrit, CK, ALP, albumin and lactate kinetics during exercise were evaluated by collecting 25µL of blood from the tail of the animals in minutes 0, 10, 20 and 30 of exercise. RESULTS: Two-way ANOVA for repeated measures and post hoc Tukey test showed significant decrease of glycemia after exercise for the DA group, significant increase in CK after exercise for the DA group, significant increase in hematocrit for both groups after exercise and maintenance of ALP after exercise for the DA group. CONCLUSION: The acute aerobic exercise was effective in controlling glucose levels in diabetic rats. However, it should be applied with caution, because it induced high CK values, suggesting possible tissue damage. .

INTRODUCCIÓN: Las respuestas al ejercicio agudo de los biomarcadores, como la fosfatasa alcalina (FA) y la creatina quinasa (CK) séricas han sido poco investigadas en ratones diabéticos. OBJETIVOS: Verificar los efectos del ejercicio físico aeróbico agudo sobre las concentraciones de CK y FA, bien como evaluar el estado hídrico en ratones diabéticos experimentales. MATERIALES Y MÉTODOS: Fueron utilizados ratones Wistar machos, adultos jóvenes, distribuidos en dos grupos: diabéticos (DA) y controles (CA). La diabetes fue inducida por medio de la administración de aloxana monohidratado Sigma(r) (32 mg/kg de peso corporal). Dos semanas después de la confirmación de la diabetes, ambos grupos fueron sometidos a una sesión aguda de natación por 30 minutos, con carga aeróbica (4,5% del peso corporal). Fueron evaluados: Glucosa, hematocrito, CK, FA, albumina y La cinética de lactato durante el ejercicio por medio de colectas de 25 µL de sangre de la cola de los animales, en los minutos 0, 10, 20 y 30 de ejercicio. RESULTADOS: ANOVA de dos factores para medidas repetidas y el test post hoc de Tukey apuntaron disminución significativa de los valores de glicemia después del ejercicio para el grupo DA, aumento significativo de CK después del ejercicio para el grupo DA, aumento significativo de hematocrito para ambos grupos después del ejercicio y mantenimiento de la FA después del ejercicio para el grupo DA. CONCLUSIÓN: El ejercicio agudo aeróbico fue eficiente en el control de los niveles glicémicos de ratones diabéticos. Entretanto, debe ser aplicado con cautela, pues indujo altos valores de CK, sugiriendo posibles lesiones tisulares. .

Correlações entre parâmetros aeróbios e desempenho em esforços intermitentes de alta intensidade / Relationship between aerobic parameters and intermittent high-intensity effort performance

O objetivo do presente estudo foi investigar as possíveis correlações entre parâmetros provenientes de um esforço intermitente de alta intensidade (RAST) e variáveis relacionadas ao metabolismo aeróbio (limiar anaeróbio; LAN, consumo máximo de oxigênio;VO2MAX e intensidade correspondente ao VO2MAX;iVO2MAX). Oito jogadores de futebol (16±1 anos) participaram do estudo. Os atletas foram submetidos a um teste progressivo para a determinação dos índices aeróbios e a seis esforços máximos de 35m separados por 10s de recuperação (RAST). As variáveis do RAST não foram correlacionadas ao VO2MAX e ao LAN. Entretanto, as potência média absoluta e relativa ao peso corporal, apresentaram correlações significativas com a iVO2MAX (r=0,79 e r= 0,85, respectivamente). O índice de fadiga e a potência pico relativa também foram significativamente correlacionados com a iVO2MAX (r=-0,57 e r=0,73, respectivamente). Pode-se concluir que em esforços como o RAST, com breves períodos de recuperação, a única variável aeróbia correlacionada ao desempenho foi a iVO2MAX.

The purpose of the study was to examine the relationships between intermittent high-intensity efforts (RAST) parameters and variables related to aerobic metabolism (anaerobic threshold; LAN, maximal oxygen uptake; VO2MAX and velocity correspondent to VO2MAX;iVO2MAX). Eight under-17 (U17) soccer players (16±1 years) participated in the study. The participants were submitted to a graded exercise test and six maximal sprints of 35m with 10 seconds of passive recovery between each effort (RAST). The RAST parameters were not significant correlated with VO-2MAX and LAN. However absolute and relative mean power were significantly correlated with iVO2MAX (r=0.79 e r= 0.85, respectively). Furthermore, the fatigue index and the relative peak power were significantly correlated with the iVO2MAX (r=-0,57 e r=0,73, respectively). In conclusion, the only aerobic variable correlated with performance in consecutive efforts with brief recovery periods, such as RAST, is iVO2MAX.

Comparação da potência anaeróbia mensurada pelo teste de RAST em diferentes condições de calçado e superfícies / Comparison of the anaerobic power measured by the RAST test at different footwear and surfaces conditions

INTRODUÇÃO: O Running Anaerobic Sprint Test (RAST) tem sido considerado um teste válido para avaliação anaeróbia. Entretanto, como a superfície e o calçado podem afetar alguns parâmetros mensurados durante o exercício, isso pode modificar os parâmetros do RAST. OBJETIVO: Comparar as variáveis do RAST mensuradas utilizando chuteiras na grama (RAST CG) e tênis na pista (RAST TP). MÉTODOS: Oito jogadores de futebol (da categoria sub-17) participaram do estudo. Os participantes realizaram dois RAST (intervalo > 24 h). O RAST consistiu em seis corridas máximas de 35m com 10s de intervalo passivo entre cada corrida. O tempo de cada esforço foi registrado para determinação da potência pico (PP), potência média (PM) e índice de fadiga (IF). Após o sexto esforço, amostras sanguíneas foram coletadas para determinação da lactacidemia ([Lac]). RESULTADOS: Durante o RAST TP, a PP (763,1 ± 87,2 W) e PM (621,6 ± 68,1 W) foram significativamente superiores às PP e PM mensuradas em RAST CG (PP = 667,3 ± 67,0 W e PM = 555,9 ± 74,7 W), enquanto que as [Lac] observadas em RAST TP (7,3 ± 1,8 mmol.L-1) foram significativamente inferiores às mensuradas em RAST CG (9,9 ± 3,2 mmol.L-1). No entanto, o IF não foi significativamente diferente (RAST TP = 32,5 ± 8,3%; RAST CG = 34,1 ± 6,6%). Significativas correlações foram observadas entre as PM (r = 0,90) e as [Lac] (r = 0,72). CONCLUSÃO: Podemos concluir que as variáveis do RAST são influenciadas pela superfície e calçado utilizados, com valores superiores observados em RAST TP.

INTRODUCTION: Running Anaerobic Sprint Test (RAST) has been considered a valid test for anaerobic evaluation. However, since the floor surfaces and footwear can affect some outcomes measured during exercise, this also can modify the RAST outcomes. OBJECTIVE: Was to compare the RAST outcomes measured using soccer cleats on grass (RAST SCG) and using shoes on the track (RAST ST). METHODS: Eight young male soccer players (under-17 category; 16±1 years) participated in the study. The subjects performed two RAST on different days (recovery > 24h). The RAST test consisted of six 35-meter maximal running performance with a 10-second recovery between each run. Running time during each effort was recorded to determine peak power (PP), mean power (MP) and fatigue index (FI); and blood samples were collected after each test to determine lactatemia ([Lac]). RESULTS: PP (763.1 ± 87.2 W) and MP (621.6 ± 68.1 W) were higher in RAST ST than RAST SCG (PP = 667.3 ± 67.0 W e PM = 555.9 ± 74.7 W), while [Lac] measured during RAST ST (7.3 ± 1.8 mmol.L-1) was lower than the one measured in RAST SCG (9.9 ± 3.2 mmol.L-1). However, the FI did not statistically differ (RAST ST = 32.5 ± 8.3%; RAST SCG = 34.1 ± 6.6%). Significant correlations were observed between MP values (r = 0.90) and [Lac] values (r = 0.72). CONCLUSION: We can conclude that the RAST variables are affected by floor surface and footwear, with higher values being observed during RAST ST condition.

Feed restriction and a diet's caloric value: The influence on the aerobic and anaerobic capacity of rats.

BACKGROUND: The influence of feed restriction and different diet's caloric value on the aerobic and anaerobic capacity is unclear in the literature. Thus, the objectives of this study were to determine the possible influences of two diets with different caloric values and the influence of feed restriction on the aerobic (anaerobic threshold: AT) and anaerobic (time to exhaustion: Tlim) variables measured by a lactate minimum test (LM) in rats. METHODS: We used 40 adult Wistar rats. The animals were divided into four groups: ad libitum commercial Purina® diet (3028.0 Kcal/kg) (ALP), restricted commercial Purina® diet (RAP), ad libitum semi-purified AIN-93 diet (3802.7 Kcal/kg) (ALD) and restricted semi-purified AIN-93 diet (RAD). The animals performed LM at the end of the experiment, 48 h before euthanasia. Comparisons between groups were performed by analysis of variance (p < 0,05). RESULTS: At the end of the experiment, the weights of the rats in the groups with the restricted diets were significantly lower than those in the groups with ad libitum diet intakes. In addition, the ALD group had higher amounts of adipose tissue. With respect to energetic substrates, the groups subjected to diet restriction had significantly higher levels of liver and muscle glycogen. There were no differences between the groups with respect to AT; however, the ALD group had lower lactatemia at the AT intensity and higher Tlim than the other groups. CONCLUSIONS: We conclude that dietary restriction induces changes in energetic substrates and that ad libitum intake of a semi-purified AIN-93 diet results in an increase in adipose tissue, likely reducing the density of the animals in water and favouring their performance during the swimming exercises.