João Paulo Loures

Specific Determination of Maximal Lactate Steady State in Soccer Players

Abstract Loures, JP, Chamari, K, Ferreira, EC, Campos, EZ, Zagatto, AM, Milioni, F, da Silva, ASR, and Papoti, M. Specific determination of maximal lactate steady state in soccer players. J Strength Cond Res 29(1): 101–106, 2015—The aim of this study was to establish the validity of the anaerobic threshold (AT) determined on the soccer-specific Hoff circuit (ATHoff) to predict the maximal lactate steady-state exercise intensity (MLSSHoff) with the ball. Sixteen soccer players (age: 16.0 ± 0.5 years; body mass: 63.7 ± 9.0 kg; and height: 169.4 ± 5.3 cm) were submitted to 5 progressive efforts (7.0–11.0 km·h−1) with ball dribbling. Thereafter, 11 players were submitted to 3 efforts of 30 minutes at 100, 105, and 110% of ATHoff. The ATHoff corresponded to the speed relative to 3.5 mmol·L−1 lactate concentration. The speed relative to 4.0 mmol·L−1 was assumed to be ATHoff4.0, and the ATHoffBI was determined through bisegmented adjustment. For comparisons, Students t-test, intraclass correlation coefficient (ICC), and Bland and Altman analyses were used. For reproducibility, ICC, typical error, and coefficient of variation were used. No significant difference was found between AT test and retest determined using different methods. A positive correlation was observed between ATHoff and ATHoff4.0. The MLSSHoff (10.6 ± 1.3 km·h−1) was significantly different compared with ATHoff (10.2 ± 1.2 km·h−1) and ATHoffBI (9.5 ± 0.4 km·h−1) but did not show any difference from LAnHoff4.0 (10.7 ± 1.4 km·h−1). The MLSSHoff presented high ICCs with ATHoff and ATHoff4.0 (ICC = 0.94; and ICC = 0.89; p ⩽ 0.05, respectively), without significant correlation with ATHoffBI. The results suggest that AT determined on the Hoff circuit is reproducible and capable of predicting MLSS. The ATHoff4.0 was the method that presented a better approximation to MLSS. Therefore, it is possible to assess submaximal physiological variables through a specific circuit performed with the ball in young soccer players.

Comparação da potência anaeróbia mensurada pelo teste de RAST em diferentes condições de calçado e superfícies

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 (RASTSCG) and using shoes on the track (RASTST). 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 RASTST than RASTSCG (PP = 667.3 ± 67.0 W e PM = 555.9 ± 74.7 W), while [Lac] measured during RASTST (7.3 ± 1.8 mmol.L-1) was lower than the one measured in RASTSCG (9.9 ± 3.2 mmol.L-1). However, the FI did not statistically differ (RASTST = 32.5 ± 8.3%; RASTSCG = 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 RASTST condition

Correlações entre parâmetros aeróbios e desempenho em esforços intermitentes de alta intensidade

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.

The Hoff circuit test is more specific than an incremental treadmill test to assess endurance with the ball in youth soccer players

The assessment of aerobic endurance is important for training prescription in soccer, and is usually measured by straight running without the ball on a track or treadmill. Due to the ball control and technical demands during a specific soccer test, the running speeds are likely to be lower compared to a continuous incremental test. The aim of the present study was to compare the heart rate (HR), rating of perceived exertion (RPE) and speeds corresponding to 2.0 mmol∙L-1, 3.5 mmol∙L-1, lactate threshold (Dmax method) and peak lactate determined in the laboratory and in the Hoff circuit soccer-specific test. Sixteen soccer players (16±1 years) underwent two incremental tests (laboratory and Hoff circuit tests). The speeds were significantly higher in the treadmill test than on the Hoff circuit (2.0 mmol∙L-1: 9.5±1.2 and 8.1±1.0 km∙h-1; 3.5 mmol∙L-1: 12.0±1.2 and 10.2±1.1 km∙h-1; Dmax: 11.4±1.4 and 9.3±0.4 km∙h-1; peak lactate: 14.9±1.6 and 10.9±0.8 km∙h-1). The HR corresponding to 3.5 mmol∙L-1 was significantly higher on the Hoff circuit compared to the laboratory test (187.5±18.0 and 178.2±17.6 bpm, respectively; P <0.001), while the RPE at the last incremental stage was lower on the Hoff circuit (P < 0.01). The speeds during the Hoff specific soccer test and the HR corresponding to 2.0 mmol∙L-1, 3.5 mmol∙L-1 and Dmax/threshold were different compared with the laboratory test. The present study shows that it is possible to assess submaximal endurance related variables specifically in soccer players.

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

BackgroundThe influence of feed restriction and different diets 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.MethodsWe 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).ResultsAt 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.ConclusionsWe 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.

The effects of acute exercise on serum biomarkers in diabetics rats

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 (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.

Efectos del ejercicio agudo sobre biomarcadores de suero em ratones diabeticos

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 (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.

Efeitos do exercicio agudo sobre biomarcadores sericos de ratos diabeticos

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 (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.