Backward extrapolation technique: analysis of different criteria after supramaximal exercise in cycling.

BACKGROUND: Backward extrapolation technique (BE) was used to estimate V̇O2 from postexercise measuring, eliminating oronasal mask (OM) during the efforts. Despite its advantage, literature presents discrepancy in applied methods. Thus, the first aim of this study was to compare different mathematical criteria to estimate values of V̇O2 during a supramaximal effort (V̇O2PEAK), while the second aim was to verify the effects of OM on cycling performance. METHODS: Twenty-four male cyclists (35±6 years, 81.3±8.9 kg, 180±6 cm) performed three days of tests, with at least 24 h of interval between each test. Firstly, a graded exercise test was applied to determine V̇O2max and your correspondent intensity (MAP). The second and the third day were destined to supramaximal efforts at 120% of MAP, performed with (Supramask) and without (Suprabe) oronasal mask (OM) in a randomized order. After Suprabe, OM was coupled, and BE was applied. Sixty-six values of V̇O2 were obtained based on a linear regression fitting. RESULTS: V̇O2peak can be estimated using different curve lengths. However, only curves between 20 and 60 s with extrapolation to 3 s or lesser shows at least one consistent criterion. The 60 s curve extrapoled to -3 s was the most accurate criteria (P=0.723; ES=-0.055; r=0.824; Bias=-0.36 and LoA=7.72 mL.kg.min-1). Performance was not impaired with OM and was similar in both condition (P=0.84, ES=0.04). CONCLUSIONS: We conclude that it was possible to accurately estimate V̇O2 values of a supramaximal effort without any respiratory apparatus with a time-efficient analysis. Therefore, we recommended the use of a 60 seconds V̇O2 curve analysis with a negative extrapolation for 3 seconds.

Dynamics of Recovery of Physiological Parameters After a Small-Sided Game in Women Soccer Players.

Purpose: Training methods based on small-sided game (SSG) seem to promote physiological and tactical benefits for soccer players as they present characteristics more specific to the game. Thus, the main objective of the present study was to analyze the hormonal, biochemical, and autonomic parameters in an acute manner and the recovery dynamics (up to 72 h after) in a SSG. Methods: Thirteen professional female soccer players participated in the study (18.8 ± 0.8 years, body mass 59.4 ± 6.2 kg, and height 1.68 ± 0.05 m). During and after the SSG session (4 min × 4 min separated by 3 min of passive interval and 120 m2 coverage per player), autonomic modulation was analyzed in the time and frequency domains using heart rate variability, and blood samples (5 ml) were collected before (0 h) and after (10 min and 24, 48, 72 h) the SSG for biochemical and hormonal analysis. Results: The SSG induced an increase effect for LF (low frequency) (92,52%; Very likely increase) and a decrease effect for HF (high frequency) values (-65,72%; Very likely decrease), after 10 min of recovery. The LF/HF increase after 10 min of recovery (386,21%; Very likely increase). The RMSSD (square root of the mean squared differences of the successive N-N intervals) and pNN50 (measure of the number of adjacent NN intervals which differ by more than 50 ms) values presented a decrease effect 10 min after SSG (61,38%; Very likely decrease and-90%; Very likely decrease). The CK (creatine kinase) values presented no changes 10 min after SSG. The LDH (lactate dehydrogenase) values presented an increase effect 10 min after the SSG (19,22%; Likely increase). Both testosterone and cortisol concentrations presented the same behavior after SSG, where no alterations were observed with after 10 min (<0,37%; Most likely trivial). Conclusion: The SSG promoted significant cardiovascular stress that was restored within the first 24 h of recovery. Parasympathetic parameters continued to increase while sympathetic parameters declined significantly during the 72 h of recovery. In addition, the reduced game did not alter biochemical or hormonal responses during the 72 h.

Effect of Endurance Training on The Lactate and Glucose Minimum Intensities.

Due to the controversy about the sensitive of lactate minimum intensity (LMI) to training and the need to develop other tool for aerobic fitness evaluation, the purpose of this study was to analyze the sensitivity of glucose minimum intensity (GMI) and LMI to endurance training. Eight trained male cyclists (21.4 ± 1.9 years, 67.6 ± 7.5 kg and 1.72 ± 0.10 m) were evaluated twice, before and after 12 weeks of training. GMI and LMI were calculated, respectively, by the lowest blood glucose and lactate values attained during an incremental test performed after a hyperlactemia induction, and VO2max was determined during standard incremental effort. The training was prescribed in three different zones and controlled by heart rate (HR). The training distribution was equivalent to 59.7%, 25.0% and 15.3% below, at and above anaerobic threshold HR respectively. The anaerobic threshold evaluated by GMI and LMI improvement 9.89 ± 4.35% and 10.28 ± 9.89 respectively, after training, but the VO2max 2.52 ± 1.81%. No differences were found between GMI and LMI in pre (218.2 ± 22.1 vs 215.0 ± 18.6 W) and post (240.6 ± 22.9 vs 237.5 ± 18.8 W) training situations. LMI and GMI were sensitive to 12-week aerobic training in cyclist; thus, both protocols can be used to assess aerobic adaptation, athletes diagnostic and prescribe training.

Lactacidemic variation and movement patterns during anaerobic power test.

BACKGROUND: After the Running Anaerobic Sprint Test (RAST) high blood lactate concentrations ([La-]) are found. However, no study verified the behavior of this metabolite during RAST. For this, the aim of the present study was to verify the implications of increase [La-] on movement patterns' in RAST performance. METHODS: Six healthy and active individuals (21.8±3.1 years, 70.9±10.8 kg and 179.7±3.3 cm) executed a standardized warm-up. Two minutes later, subjects performed RAST composed of six maximal 35-m bouts separated by 10 s of passive recovery. During RAST, 14 cameras monitored the subjects to determine tridimensional and bi-dimensional mechanics. [La-] were determined before warm-up, between each bout and after RAST. RESULTS: Significant difference in performance were found after the fifth (5.1±0.1 s) and sixth (5.4±0.3 s; P<0.04) bout in relation to the first up to fourth effort. Fatigue indexes (FI% and FIREAL) were higher from fifth bout (19.2±9.4%; 19.3±10.9%; P<0.05). No significant difference was observed in [La-] on fifth and sixth bout (8.2±2.4 mM and 9.2±2.1 mM) however, both were different from all other bouts. Flight time was different between the fifth bout (0.16±0.03 s) when compared with the first (0.12±0.01 s; P=0.01) and second (0.13±0.02s; P=0.03) bouts. CONCLUSIONS: RAST performance can be influenced by physiological changes. Biomechanical behavior does not alter performance without a sum of physiological events.

Construct validity of tests that measure kick performance for young soccer players based on cluster analysis: exploring the relationship between coaches rating and actual measures.

BACKGROUND: The main aim of this study was to verify the relationship between the classification of coaches and actual performance in field tests that measure the kicking performance in young soccer players, using the K-means clustering technique. METHODS: Twenty-three U-14 players performed 8 tests to measure their kicking performance. Four experienced coaches provided a rating for each player as follows: 1: poor; 2: below average; 3: average; 4: very good; 5: excellent as related to three parameters (i.e. accuracy, power and ability to put spin on the ball). RESULTS: The scores interval established from k-means cluster metric was useful to originating five groups of performance level, since ANOVA revealed significant differences between clusters generated (P<0.01). Accuracy seems to be moderately predicted by the penalty kick, free kick, kicking the ball rolling and Wall Volley Test (0.44≤r≤0.56), while the ability to put spin on the ball can be measured by the free kick and the corner kick tests (0.52≤r≤0.61). Body measurements, age and PHV did not systematically influence the performance. The Wall Volley Test seems to be a good predictor of other tests. CONCLUSIONS: Five tests showed reasonable construct validity and can be used to predict the accuracy (penalty kick, free kick, kicking a rolling ball and Wall Volley Test) and ability to put spin on the ball (free kick and corner kick tests) when kicking in soccer. In contrast, the goal kick, kicking the ball when airborne and the vertical kick tests exhibited low power of discrimination and using them should be viewed with caution.

Reproducibility of Running Anaerobic Sprint Test for soccer players.

BACKGROUND: Although the Running Anaerobic Sprint Test (RAST) presents reliability when performed on firmer surfaces (i.e. athletic track), its application on less rigid surfaces can compromise the measure determinations. Thus, the aim of the present study was to evaluate the RAST reliability for soccer players performing on grass, and wearing soccer cleats. METHODS: Fourteen soccer players (16±1 years, 72.3±10.3 kg, 177.2±8.4 cm, 14.5±5.3% of fat mass, and VO2MAX of 52.0±5.1 mL∙kg-1∙min-1) performed six maximal 35-meter effort interspersed by 10s of passive rest (RAST). After 48h the RAST was repeated to test the reliability. The main variables analyzed were the peak power (PP), mean power (MP), fatigue indexes (FI), and impulse (ImP). The reproducibility of test and re-test was tested through the Student's t Test to paired samples, intraclass correlation (ICC), typical error (TE), and coefficient of variation (CV%). RESULTS: The PP (test=701.4±169.5 W; re-test 712.4±142.3 W), MP (test=538.6±111.4 W; re-test=551.9±101.1 W), and the ImP (test=2841.2±461.8 N∙s; re-test=2797.2±575.9 N∙s) were not different, presented significant correlation between the situations (ICC=0.88; 0.96 e 0.93; respectively), and low values of TE (71.9 W; 30.6 W e 191.1 N∙s, respectively) and CV% (10.2%; 5.9% e 6.8%, respectively). The FI (test=40.1±5.8; re-test=38.7±7.7%) were not significantly related between the test and re-test, and presented high TE (5.7%) and CV% (14.4%). CONCLUSIONS: We can conclude that RAST presents high reliability when performed on grass with soccer cleats, just as rigid surfaces. Besides, the ImP is more robust than the.