Influência da aptidão aeróbia no running anaerobic sprint test (RAST)

The aim of this study was to investigate the possible influence of different levels of aerobic fitness (VO2MAX) on the parameters of the running anaerobic sprint test (RAST). Thirty-eight subjects (Age = 18.1 ± 2.5 years, Height = 173 ± 1 cm and Body mass = 65.1 ± 6.5 kg) were classified into two groups, low and high aerobic fitness (LAF: n = 22 and HAF: n = 16). The VO2MAX was determined by an incremental exercise performed until exhaustion. The RAST was composed of six maximal efforts of 35m separated by 10s passive recovery. The VO2MAX was significantly different between groups (LAF = 51.7 ± 1.9 mL.kg -1.min-1; HAF = 58.6 ± 3.1 mL.kg -1.min-1). The mean power (MP) was significantly higher in the LAF (552.7 ± 132.1 W) in relation to the HAF group (463.6 ± 132.8 W). The impulse (ImP) was significantly correlated with the VO 2MAX in HAF. It can be concluded that there is an indication that the aerobic metabolism exerts an influence on the completion of RAST.

The Positive Effects of Priming Exercise on Oxygen Uptake Kinetics and High-Intensity Exercise Performance Are Not Magnified by a Fast-Start Pacing Strategy in Trained Cyclists

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeito do nadar sobre o desempenho do pedal e corrida no triathlon super-sprint

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The effect of prior exercise intensity on oxygen uptake kinetics during high-intensity running exercise in trained subjects

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Prior Heavy-Intensity Exercise's Enhancement of Oxygen-Uptake Kinetics and Short-Term High-Intensity Exercise Performance Independent of Aerobic-Training Status

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Anaerobic energy provision does not limit Wingate exercise performance in endurance-trained cyclists

[EN] The aim of this study was to evaluate the effects of severe acute hypoxia on exercise performance and metabolism during 30-s Wingate tests. Five endurance- (E) and five sprint- (S) trained track cyclists from the Spanish National Team performed 30-s Wingate tests in normoxia and hypoxia (inspired O(2) fraction = 0.10). Oxygen deficit was estimated from submaximal cycling economy tests by use of a nonlinear model. E cyclists showed higher maximal O(2) uptake than S (72 +/- 1 and 62 +/- 2 ml x kg(-1) x min(-1), P < 0.05). S cyclists achieved higher peak and mean power output, and 33% larger oxygen deficit than E (P < 0.05). During the Wingate test in normoxia, S relied more on anaerobic energy sources than E (P < 0.05); however, S showed a larger fatigue index in both conditions (P < 0.05). Compared with normoxia, hypoxia lowered O(2) uptake by 16% in E and S (P < 0.05). Peak power output, fatigue index, and exercise femoral vein blood lactate concentration were not altered by hypoxia in any group. Endurance cyclists, unlike S, maintained their mean power output in hypoxia by increasing their anaerobic energy production, as shown by 7% greater oxygen deficit and 11% higher postexercise lactate concentration. In conclusion, performance during 30-s Wingate tests in severe acute hypoxia is maintained or barely reduced owing to the enhancement of the anaerobic energy release. The effect of severe acute hypoxia on supramaximal exercise performance depends on training background.

The effect of ego depletion on sprint start reaction time

In the current study, we consider that optimal sprint start performance requires the self-control of responses. Therefore, start performance should depend on athletes' self-control strength. We assumed that momentary depletion of self-control strength (ego depletion) would either speed up or slow down the initiation of a sprint start, where an initiation that was sped up would carry the increased risk of a false start. Applying a mixed between- (depletion vs. nondepletion) and within- (before vs. after manipulation of depletion) subjects design, we tested the start reaction times of 37 sport students. We found that participants' start reaction times decelerated after finishing a depleting task, whereas it remained constant in the nondepletion condition. These results indicate that sprint start performance can be impaired by unrelated preceding actions that lower momentary self-control strength. We discuss practical implications in terms of optimizing sprint starts and related overall sprint performance.

Accuracy of continuous glucose monitoring during differing exercise conditions.

AIM Depending on intensity, exercise may induce a strong hormonal and metabolic response, including acid-base imbalances and changes in microcirculation, potentially interfering with the accuracy of continuous glucose monitoring (CGM). The present study aimed at comparing the accuracy of the Dexcom G4 Platinum (DG4P) CGM during continuous moderate and intermittent high-intensity exercise (IHE) in adults with type 1 diabetes (T1DM). METHODS Ten male individuals with well-controlled T1DM (HbA1c 7.0±0.6% [54±6mmol/mol]) inserted the DG4P sensor 2 days prior to a 90min cycling session (50% VO2peak) either with (IHE) or without (CONT) a 10s all-out sprint every 10min. Venous blood samples for reference glucose measurement were drawn every 10min and euglycemia (target 7mmol/l) was maintained using an oral glucose solution. Additionally, lactate and venous blood gas variables were determined. RESULTS Mean reference blood glucose was 7.6±0.2mmol/l during IHE and 6.7±0.2mmol/l during CONT (p<0.001). IHE resulted in significantly higher levels of lactate (7.3±0.5mmol/l vs. 2.6±0.3mmol/l, p<0.001), while pH values were significantly lower in the IHE group (7.27 vs. 7.38, p=0.001). Mean absolute relative difference (MARD) was 13.3±2.2% for IHE and 13.6±2.8% for CONT suggesting comparable accuracy (p=0.90). Using Clarke Error Grid Analysis, 100% of CGM values during both IHE and CONT were in zones A and B (IHE: 77% and 23%; CONT: 78% and 22%). CONCLUSIONS The present study revealed good and comparable accuracy of the DG4P CGM system during intermittent high intensity and continuous moderate intensity exercise, despite marked differences in metabolic conditions. This corroborates the clinical robustness of CGM under differing exercise conditions. CLINICAL TRIAL REGISTRATION NUMBER ClinicalTrials.gov NCT02068638.

Bicarbonato ingestion has no ergogenic effect on consecutive all out sprint test in MWX elite cyclists

The aim of the present study was to examine the effect of sodium bicarbonate ingestion on consecutive "all out" sprint tests, analyzing the acid-base status and its influence on performance and perceived effort. Ten elite bicycle motocross (BMX) riders (20.7 ± 1.4 years, training experience 8-12 years) participated in this study which consisted of two trials. Each trial consisted of three consecutive Wingate tests (WTs) separated by 15 min recovery. Ninety minutes prior to exercise subjects ingested either NaHCO(3) (-) (0.3 g kg(-1) body weight) or placebo. Blood samples were collected for the assessment of blood acid-base status: bicarbonate concentration ([HCO(3) (-)]), pH, base excess (BE) and blood lactate concentration ([La(-)]). Performance variables of peak power (PP), mean power (MP), time to peak power and fatigue index were calculated for each sprint. Significant differences (p < 0.05) were observed in acid-base variables [pH before WT1: 7.47 ± 0.05 vs. 7.41 ± 0.03; [HCO(3) (-)] before WT1: 29.08 ± 2.27 vs. 22.85 ± 0.24 mmol L(-1) (bicarbonate vs. placebo conditions, respectively)], but there were not significant differences in performance variables between trials [PP WT1: 1,610 ± 373 vs. 1,599 ± 370 W; PP WT2: 1,548 ± 460 vs. 1,570 ± 428 W; PP WT3: 1,463 ± 361 vs. 1,519 ± 364 W. MP WT1: 809 ± 113 vs. 812 ± 108 W; MP WT2: 799 ± 135 vs. 799 ± 124 W; MP WT3: 762 ± 165 vs. 782 ± 118 W (bicarbonate vs. placebo conditions, respectively)]. Rating of perceived effort (RPE) was not influenced nor ratings of perceived readiness. Sodium bicarbonate ingestion modified significantly the blood acid-base balance, although the induced alkalosis did not improve the Wingate test performance, RPE and perceived readiness across three consecutive WTs in elite BMX cyclists.

The reliability of ten-meter sprint time using different starting techniques

Acceleration is an important factor for success in team-sport athletes. The purpose of this investigation was to compare the reliability of 10-m sprint times when using different starting techniques. Junior male rugby players (n=15) were tested for speed over 10 m on 2 different testing sessions. Three trials of 3 different starting techniques (standing, foot, and thumb starts) were assessed. Despite large differences in the time taken to perform 10-m sprints from different starts, there was minimal difference in the typical error (similar to 0.02 seconds, or

Sprint patterns in rugby union players during competition

The purpose of this study was to characterize sprint patterns of rugby union players during competition. Velocity profiles (60 m) of 28 rugby players were initially established in testing from standing, walking, jogging, and striding starts. During competition, the individual sprinting patterns of 17 rugby players were determined from video by using the individual velocity profiles. Forwards commenced sprints from a standing start most frequently (41%), whereas backs sprinted from standing (29%), walking (29%),jogging (29%), and occasionally striding (13%) starts. Forwards and backs achieved speeds in excess of 90% maximal velocity (Vmax) on 5 +/- 4 and 9 +/- 4 occasions (similar to 50% of the sprints performed), respectively, during competition. The higher frequency of sprinting for the backs compared with the forwards highlights the importance of speed training for this positional group. The similar relative distribution of velocities achieved during competition for forwards and backs suggests both positional groups should train acceleration and Vmax qualities. The backs should have a higher total volume of sprint training. Sprinting efforts should be performed from a variety of starting speeds to mimic the movement patterns of competition.