Reliability of Anaerobic Contributions during a Single Exhaustive Knee-extensor Exercise.

The total anaerobic contribution (AC[La-]+PCr) is a valid and reliable methodology. However, the active muscle mass plays an important role in the AC[La-]+PCr determination, which might influence its reliability. Thus, this study aimed to investigate the effects of two exhaustive intensities on the reliability of the AC[La-]+PCr during a one-legged knee extension (1L-KE) exercise. Thirteen physically active males were submitted to a graded exercise to determine the peak power output (PPO) in the 1L-KE. Then, two constant-load exercises were conducted to task failure at 100% (TTF100) and 110% (TTF110) of PPO, and the exercises were repeated on a third day. The blood lactate accumulation and the oxygen uptake after exercise were used to estimate the anaerobic lactic and alactic contributions, respectively. Higher values of AC[La-]+PCr were found after the TTF100 compared to TTF110 (p=0.042). In addition, no significant differences (p=0.432), low systematic error (80.9 mL), and a significant ICC (0.71; p=0.004) were found for AC[La-]+PCr in the TTF100. However, an elevated coefficient of variation was found (13.7%). In conclusion, we suggest the use of the exhaustive efforts performed at 100% of the PPO with the 1L-KE model, but its elevated individual variability must be carefully considered in future studies.

3-min All-out Test to Evaluate Aerobic and Anaerobic Indexes in Court Team Sports.

This study aimed to test the reproducibility of the 3-min all-out effort applied using shuttle running and compare its values to aerobic parameters. On the first day, 14 futsal players underwent an exhaustive test to determine the maximal incremental speed (MIS) and anaerobic threshold (AnT). On the second day, the participants performed the 3-min all-out effort (n=14), which was repeated after 48 h (third day) to test its reproducibility (n=11). Peak oxygen consumption (V̇ O2PEAK) and peak blood lactate concentrations ([La-]) were determined from 3-min all-out efforts performed through a 20-m shuttle run on the official court. The distance covered, mean speed, and critical speed (CS) during the 3-min all-out presented direct relationships with aerobic parameters determined through the incremental test (r>0.62). The distance covered above CS (D') presented a direct relationship with peak lactate concentrations induced by a 3-min all-out effort (r=0.81). Despite the acceptable levels of reproducibility observed for most of the 3-min all-out variables, the minimal detectable change for D' was high (72%). Our results demonstrated the potential use of mean speed to evaluate aerobic fitness. However, the applicability of the 3-min all-out shuttle run test to monitor training adaptations should be avoided, at least in nonexperienced athletes.

Anaerobic Contribution Determined in Free-Swimming: Sensitivity to Maturation Stages and Validity.

Evaluation of anaerobic contribution is important under swimming settings (training and modification through ages), therefore, it is expected to change during maturation. The accumulated oxygen deficit (AOD) method can be used to determine the contribution of nonoxidative energy during swimming; however, it requires several days of evaluation. An alternative method to estimate anaerobic contribution evaluation (ACALT), which can also be evaluated without snorkel (i.e., free-swimming, ACFS), has been proposed; however, these methods have never been compared. Thus, this study (i) analyzed the effect of maturation stage on ACFS during maximal 400 m swimming (Part I), and (ii) compared AOD with ACALT and ACFS, determined in a maximal 400 m effort (Part II). In Part I, 34 swimmers were divided into three groups, according to maturation stages (early-pubertal, middle-pubertal, and pubertal), and subjected to a maximal 400 m free-swimming to determine ACFS. In Part II, six swimmers were subjected to one 400 m maximal effort, and four submaximal constant efforts. The AOD was determined by the difference between the estimated demand and accumulated oxygen during the entire effort. The ACALT and ACFS (for Part I as well) was assumed as the sum of lactic and alactic anaerobic contributions. ACFS was higher in pubertal (3.8 ± 1.1 L) than early (2.1 ± 0.9 L) and middle pubertal group (2.4 ± 1.1 L). No difference was observed among absolute AOD (3.2 ± 1.3 L), ACALT (3.2 ± 1.5 L), and ACFS (4.0 ± 0.9 L) (F = 3.6; p = 0.06). Relative AOD (51.8 ± 12.2 mL·kg-1), ACALT (50.5 ± 14.3 mL·kg-1), and ACFS (65.2 ± 8.8 mL·kg-1) presented main effect (F = 4.49; p = 0.04), without posthoc difference. The bias of AOD vs. ACALT was 0.04 L, and AOD vs. ACFS was -0.74 L. The limits of agreement between AOD and ACALT were +0.9 L and -0.8 L, and between AOD and ACFS were +0.7 L and -2.7 L. It can be concluded that ACFS determination is a feasible tool to determine anaerobic contribution in young swimmers, and it changes during maturation stages. Also, ACFS might be useful to measure anaerobic contribution in swimmers, especially because it allows greater speeds.

Analysis of goal scoring patterns and match outcome during the Intercontinental Beach Soccer Cup Dubai 2019

Abstract Aim: To characterize the goal-scoring patterns and investigate the goal process on match outcome during the Intercontinental Beach Soccer Cup Dubai 2019. Methods: A set of 35 goal-scoring patterns were grouped into nine macro-categories: Match-period, Court-zone, Set-play, Open-play, Touching by players before the goal, Offensive method, Goalkeeper-line, Number of passes before the goal, and Ball trajectory. Match outcome in regular time was considered the matches resulting in a loss (n=16), draw (n=8), or win (n=16). The offensive sequences that resulted in the goal were analyzed in all 20 matches during the competition (n=138 goals). Results: The most goals were scored in Open-play (69%), during the 2nd and 3rd periods (36% for each), near to goal (Zone 4; 50%), preceded by 1-touch (67%) and 0-pass (29%), using positional attack (46%), without goalkeeper-line (68%), and with high-ball trajectory (51%). In addition, won matches presented a higher number of goals in Zone 4, 1-touch, Counterattack, 4v4 goal-successful, Receiving pass, Sand-touch, and High-ball compared to draw and loss matches (p<0.001−0.03; Effect Size [ES]=1.24−2.58, large). Conclusion: In summary, winning teams scored their goals mainly in open-play situations and without a goalkeeper-line, using counterattacks to achieve zones near the opponent's goals, and implementing a direct offensive style. In addition, goals scored were usually preceded by 1-touch, both through high-ball and sand-touch ball trajectory. Coaches and practitioners may consider these goal processes to train prescription and deep understanding of the process to goal in elite Beach soccer.

Effect of non-nucleoside reverse transcriptase inhibitors and protease inhibitors on serum levels of myeloperoxidase and C-reactive protein in HIV-infected individuals

Abstract It remains unclear whether increased inflammatory and cardiovascular risk biomarkers differ depending on the class of antiretroviral that is used. This study evaluated the plasma levels of inflammatory and cardiovascular risk biomarkers, such as MPO, hs-CRP, glucose, lipid profile, ALT (GPT), AST (GOT), urea and creatinine, as well as the blood count, of all the 164 participants in the study, either infected or un-infected with HIV. Thirty of the 104 HIV-infected individuals did not receive any antiretroviral; twenty-four of them were treated with non-nucleoside reverse transcriptase inhibitor class; and fifty took protease inhibitors. The control group consisted of sixty non-HIV infected individuals. In the case of the HIV-infected volunteers, the CD4+ T lymphocyte counts and viral load were also analyzed. Regardless of the hematological and biochemical changes resulting from the antiretroviral therapy (ART), the MPO and hs-CRP values significantly increased for the HIV-infected individuals (treated or untreated), irrespective of the class of ART that was used. This is important because these biomarkers are designed to be predictors of the risk of cardiovascular disease. The results of this study provide supporting evidence for the hypothesis that HIV-infected individuals are at increased risk of developing cardiovascular disease related to chronic inflammations, despite virological control with ART, and regardless of the class of ART that is used.

Corrigendum: Proposal of a Conditioning Activity Model on Sprint Swimming Performance.

[This corrects the article DOI: 10.3389/fphys.2020.580711.].

Acute Behavior of Oxygen Consumption, Lactate Concentrations, and Energy Expenditure During Resistance Training: Comparisons Among Three Intensities.

Purpose: This study aimed to compare the oxygen consumption, lactate concentrations, and energy expenditure using three different intensities during the resistance training sessions. Methods: A total of 15 men (22.9 ± 2.61 years) experienced in resistance training underwent 3 sessions composed of 8 exercises (chest press, pec deck, squat, lat pull-down, biceps curl, triceps extension, hamstring curl, and crunch machine), which were applied in the same order. The weight lifted differed among the sessions [high session: 6 sets of 5 repetitions at 90% of 1-repetition maximum (1-RM); intermediary session: 3 sets of 10 repetitions at 75% of 1-RM; and low session: 2 sets of 15 repetitions at 60% of 1-RM]. The oxygen consumption (VO2)-during and after (excess post-exercise oxygen consumption (EPOC)) the session, blood lactate concentration, and energy expenditure (i.e., the sum of aerobic and anaerobic contributions, respectively) were assessed. Results: The VO2 significantly decreased in the function of the weight lifting (F (2.28) = 17.02; p < 0.01; η G 2 = 0.32). However, the aerobic contributions significantly increase in the function of the weight lifting (F (2.28) = 79.18; p < 0.01; η G 2 = 0.75). The anaerobic contributions were not different among the sessions (p > 0.05; η G 2 < 0.01). Thus, the total energy expenditure during the session (kcal) significantly increased in the function of the weight lifting (F (2.28) = 86.68; p < 0.01; η G 2 = 0.75). The energy expenditure expressed in time unit (kcal·min-1) was higher in low session than in high session (F (2.28) = 6.20; p < 0.01; η G 2 = 0.15). Conclusion: The weight lifted during resistance training-induced different physiological responses, which induced higher energy expenditure per unit of time during the low session.

Determination of Maximum Accumulated Oxygen Deficit Using Backward Extrapolation.

This study aimed to compare the Maximum Accumulated Oxygen Deficit determined by the conventional method (MAODC) with that determined by the backward extrapolation technique (MAODEXTR) in runners. Fourteen runners underwent a maximal incremental test for determination of iVO2MAX, ten submaximal efforts (50-95% of iVO2MAX for 7 min). During the submaximal efforts oxygen consumption (VO2) values were obtained conventionally and through the backward extrapolation technique (~ 3 s after the end of each effort). A supramaximal effort (110% of iVO2MAX) (tLimC) and five supramaximal bouts (tLimEXTR) were performed. MAODC and MAODEXTR were determined from the difference between the VO2 accumulated during tLimC and tLimEXTR and the predicted values. The tLimC was lower than tLimEXTR (164.06±36.32 s, 200.23±63.78 s, p<0.05). No significant differences were found between absolute and relative MAODC and MAODEXTR values, however, low intraclass correlations (0.26 and 0.24), high typical errors (2.03 L and 24 mL∙kg-1) were observed, and coefficients of variation (46 and 48%), respectively. The graphical analysis of the differences showed agreement and correlation between the methods (r=0.86 and 0.85). Thus, it can be concluded that the MAODEXTR is not a valid method for estimating the anaerobic capacity of runners, moreover, unreliable.

Proposal of a Conditioning Activity Model on Sprint Swimming Performance.

This study aimed to propose a conditioning activity (CA) model to stimulate improvement on neuromuscular responses, mechanical parameters and for the 50-m freestyle swimming. Thirteen male swimmers (19 ± 3 years and performances of 77% in relation to World Championship records) performed four CA protocols followed by a maximum performance in the 50-m freestyle. In the first protocol (P1) swimmers performed a standard warm-up (∼15 min); in the second protocol (P2) lunges (3 × 85% of the one-repetition maximum); in the third (P3) pull-ups (3 maximum repetitions) and box jumps 40 cm high and 60 cm deep (1 × 5 with 10% of the corporal weight); and in the fourth protocol (P4) a combination of exercises from the second and third protocols. CA protocols had no effect on the standard warm-up. However, P2 performance (27.01 ± 1.25 s) was similar to P1 (27.01 ± 1.18 s) and presented higher positive effects in mechanical parameters for the swim start performance in comparison to other protocols, contributing to improvements in the 50-m freestyle. In addition, turnaround time also had a negative effect, mainly in P3 (3.12 ± 0.28 s), signaling the improvement of this variable in all protocols (P1: 3.30 ± 0.38 s; P2: 3.17 ± 0.30 s; P4: 3.17 ± 0.34 s). P2 (after: 80 ± 11%; before: 82.7 ± 9.9%) and P3 (after: 82.7 ± 9.9%; before: 85.1 ± 9.7%) presented a possible positive effect on the percentage of voluntary activation in relation to P1 (after: 79.3 ± 10.7%; before: 76.3 ± 12%). In conclusion, the proposed conditioning activity protocols were not efficient for performance improvement in the 50-m freestyle compared to the standard model and seem to specifically influence each phase of the event.

Effects of Match-Related Contextual Factors on Weekly Load Responses in Professional Brazilian Soccer Players.

This study aimed to quantify the weekly training load distributions according to match location, opponent standard, and match outcome in professional soccer players. Rate-of-perceived-exertion-based training load (sRPE) and distance- and accelerometry-based measures were monitored daily during 52 training sessions and 11 matches performed by 23 players. Athletes who played ≥ 60 min during non-congested weeks were considered for data analysis. The training days close to away matches (e.g., one day before the match = MD-1) presented greater sRPE, distance-based volume measures, and mechanical work (player load) compared to the training days close to home matches (p = 0.001-0.002; effect size (ES) = medium-large). The most distant days of the home matches (e.g., five days before the match = MD-5) presented higher internal and external loads than before away matches (p = 0.002-0.003, ES = medium). Higher sRPE, distance-based volume measures, and mechanical work were found during the middle of the week (e.g., three days before the match, MD-3) before playing against bottom vs. medium-ranking teams (p = 0.001-0.01, ES = small-medium). These metrics were lower in MD-5 before matches against bottom vs. medium-ranking opponents (p = 0.001, ES = medium). Higher values of all external load measures were observed during the training session before winning matches (MD-1) compared to a draw or loss (p < 0.001-0.001, ES = medium-large). In conclusion, the training load distribution throughout the week varied considerably according to match-contextual factors.

The rapid recovery of vertical force propulsion production and postural sway after a specific fatigue protocol in female handball athletes.

BACKGROUND: Muscle fatigue is characterized by a decrease in muscle performance, accompanied by an increase in perceived exertion to produce a desired amount of force. The duration of the fatigue effects is not completely clear regarding postural sway and force production in athletes. RESEARCH QUESTION: What is the effect of a specific fatigue protocol in postural sway and force production in female handball athletes and the recovery time necessary for these variables? METHODS: Twenty female handball athletes participated in this study. Specific handball actions composed the fatigue protocol in the format of a circuit with the gradual increment of laps. They stood upright in one-leg posture on a force plate. For the maximum propulsion force (FMAX), they performed a countermovement jump on the force plate. The center of pressure (COP) and the FMAX were obtained at baseline, immediately after the exhaustion due to the fatigue protocol and every minute during the first 10 min of the recovery phase. RESULTS: The FMAX decreased ∼9.5% after the fatigue protocol, whereas de COP area increased 224%. During the recovery phase, the FMAX and the COP area returned to baseline values after five minutes. SIGNIFICANCE: The first five minutes immediately after the fatigue protocol represent the time interval where the fatigue effects are still present. Future studies willing to investigate the effects of fatigue in athletes should perform the analysis within this short time-window.

Analysis of the heart rate deflection point as a tool for exercise prescription in subjects with COPD - a cross-sectional study.

Background: Prescription of exercise training in subjects with chronic obstructive pulmonary disease (COPD) remains a challenge in clinical practice. The heart rate deflection point (HRDP) is an option to reduce costs, reflects the anaerobic threshold and it is noninvasive; however its applicability in COPD is still unknown. Aim: To compare HRDP with gas exchange threshold values (GET) in subjects with COPD. Methods: Thirty-one subjects were evaluated in this cross-sectional study, diagnosed with COPD. The subjects performed an incremental exercise test on a treadmill to determine the GET, peak oxygen consumption (VO2PEAK), speed corresponding to VO2PEAK (sVO2PEAK), and peak values of heart rate (HRPEAK). To determine HRDP the heart rate values observed were plotted as a function of intensity. Results: The HRDP was visible in 96.77% of subjects. There was no difference between HRDP and GET (p = 0.07) and a moderate intraclass correlation coefficient (ICC): 0.74 [0.52-0.87] and high limits of agreements were presented (±1.1 km·h-1). Conclusion: The HRDP cannot be used to determine the limits between the physiological domains of these subjects. Thus, although significant correlation was found between HRDP and GET, their application for training prescription and monitoring in subjects with COPD proved to be limited.

Relationships Between Aerobic and Anaerobic Parameters With Game Technical Performance in Elite Goalball Athletes.

Our aims were to compare physiological parameters from the laboratory environment (LaB) and simulated goalball games (GaM), test relationships between physiological parameters in the laboratory and game technical performance (GTP), and examine the associations between physiological and technical responses during games. Seven elite athletes from the Brazilian National Team performed in LaB environment; (i) an incremental test to determine peak oxygen consumption (O2PEAK), its corresponding speed, and peak blood lactate concentration and (ii) submaximal and supramaximal efforts to estimate maximal anaerobic contribution (AnC). In GaM condition, simulated games were also performed to determine physiological responses throughout the game, and to analyze the GTP (number of throws, defenses, recovery, and density of actions). No correlations (unclear) were found between laboratory and games analyses for O2PEAK [47.3 (17.2) vs. 25.8 (18.2) mL⋅Kg-1⋅min-1], peak blood lactate concentrations [10.2 (5.4) vs. 2.0 (0.7) mM], and total AnC [21.0 (14.0) vs. 4.8 (6.1) mL Kg-1]. O2PEAK in the laboratory condition presented very likely correlations with throw and recovery frequency in games (r = -0.87 and confidence interval [CI] = 0.41; r = -0.90 and CI = 0.35; respectively). Oxygen consumption remained above baseline while blood lactate concentration remained unchanged during the games. The very likely correlation between anaerobic alactic contribution and action density (r = 0.95 and CI = 0.25) highlights the importance of the alactic metabolism. In general, our study demonstrates that goalball can be characterized as a high-intensity intermittent effort, where athlete performance is based on aerobic metabolism predominance while determinant actions are supplied by the anaerobic alactic metabolism. Specifically, higher values of LaB vs. GaM highlighted the need for standardization of specific protocols for goalball evaluation, mainly for the reproduction of ecologically valid values. In addition, O2PEAK correlated with recovery frequency in the LaB condition, demonstrating that passive or low-intensity recovery between actions is fundamental to maintain performance.

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.

Critical Velocity Determined by a Non-Exhaustive Method in Subjects With COPD.

BACKGROUND: Exercise training is an effective and low-cost tool for COPD rehabilitation. Thus, validating a non-exhaustive method to determine a patient's anaerobic threshold would be a very interesting tool in practical settings. We aimed to test the reproducibility of critical velocity values determined in a non-exhaustive manner (CVNE) and tolerance for exercise performed at this physiological marker in subjects with COPD. METHODS: Twelve subjects with COPD were evaluated in this cross-sectional study. The study was divided into 2 phases: Phase A consisted of reproducibility of CVNE for subjects with COPD, and Phase B determined the tolerance for exercise tests performed at this physiological marker. RESULTS: The proposed protocol for determining CVNE presented fair reproducibility according to blood lactate concentrations (intraclass correlation coefficient = 0.58). However, we cannot consider that the tests were reproducible due to the wide CI (0.03-0.85). Furthermore, moderate and strong correlations were observed between the CVNE determined by lactate concentration, by oxygen consumption (V̇O2 ) (r = 0.66), and by heart rate (r = 0.88). However, a high limit of agreement was observed ±1.45 km/h and ±1.55 km/h, respectively. In the tolerance for exercise test, none of the subjects presented lactate destabilization, whereas 3 tests were interrupted by oxygen saturation decline and 1 test was interrupted by hemodynamic instability. CONCLUSIONS: Although most of the subjects presented good tolerance for exercise at CVNE, fair levels of reproducibility were observed in subjects with COPD, even using lactate. Thus, the use of CVNE determined through double 3-min efforts should be considered with caution.

Relationships among the Tethered 3-min All-Out Test, MAOD and Swimming Performance.

To allow the use of the 3-min all-out parameters for anaerobic evaluation, the aim of the present study was to test its relationships to maximal accumulated oxygen deficit (MAOD) and short/middle distance performances. 9 swimmers (age 19±1 years, height 176.7±6.1 cm and body mass 68.7±6.1 kg) underwent a 3-min all-out test and MAOD procedures (10 submaximal efforts and one exhaustive effort at maximal force attained during a graded exercise test); both were applied using tethered swimming conditions. Short/middle free-swimming performances were assessed at 50, 100 and 200 m distances. Only the peak force (PF) attained during 3-min all-out test exhibited a direct relationship to MAOD (r=0.77; p=0.02). Mean force, mean force until 150 s and total impulse, which were obtained during the 3-min all-out test, exhibited inverse relationship to short/middle performances (r>-0.79; p<0.02). However, no relationship was observed between PF and performances. In addition, MAOD exhibited an inverse relationships to all performances (r>-0.72; p<0.04). Thus, the present study demonstrated that only PF can be used to evaluate the anaerobic metabolism and most of the 3-min all-out test parameters are dependent on force maintenance capacity, which is also important in short/middle performance.

Tethered Swimming for the Evaluation and Prescription of Resistance Training in Young Swimmers.

The aims of the present study were 1) to evaluate the effects of 11 weeks of a typical free-swimming training program on aerobic and stroke parameters determined in tethered swimming (Study 1; n=13) and 2) to investigate the responses of tethered swimming efforts, in addition to free-swimming sessions, through 7 weeks of training (Study 2; n=21). In both studies, subjects performed a graded exercise test in tethered swimming (GET) to determine anaerobic threshold (AnT), stroke rate at AnT (SRAnT), peak force at GET (PFGET) and peak blood lactate ([La-]GET). Participants also swam 100-, 200- and 400-m lengths to evaluate performance. In Study 2, swimmers were divided into control (i. e., only free-swimming; GC [n=11]) and tethered swimming group (i. e., 50% of the main session; GTS [n=10]). The results of Study 1 demonstrate that AnT, PFGET, [La-]GET and 200-m performance were improved with free-swimming training. The SRAnT decreased with training. In Study 2, free-swimming performance and most of the graded exercise test parameters were not altered in either group. However, [La-]GET improved only for GTS. These results demonstrate that aerobic parameters obtained in tethered swimming can be used to evaluate free-swimming training responses, and the addition of tethered efforts during training routine improves the lactate production capacity of swimmers.