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.

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.

Correction to: Beta alanine supplementation effects on metabolic contribution and swimming performance.

An amendment to this paper has been published and can be accessed via the original article.

Beta alanine supplementation effects on metabolic contribution and swimming performance.

BACKGROUND: Investigations of ß-alanine supplementation shows effects on metabolic (aerobic and anaerobic) participation and performance on swimming by a possible blood acidosis buffering. Considering this background, the objective of the present study was to analyze the effects of ß-alanine supplementation on metabolic contribution and performance during 400-m swim. METHODS: Thirteen competitive swimmers underwent a 6-week, double-blind placebo-controlled study, ingesting 4.8 g.day- 1 of ß-alanine or placebo. Before and after the supplementation period, the total anaerobic contribution (TAn) and 30-s all-out tethered swimming effort (30TS) were assessed. Anaerobic alactic (AnAl) and lactic energy (AnLa) was assumed as the fast component of excess post-exercise oxygen consumption and net blood lactate accumulation during exercise (∆[La-]), respectively. Aerobic contribution (Aer) was determined by the difference between total energy demand and TAn. In addition to conventional statistical analysis (Repeated measures ANOVA; p > 0.05), a Bayesian repeated measures ANOVA was used to evidence the effect probability (BFincl). RESULTS: No differences and effects were found between groups, indicating no supplementation effects. Repeated measures ANOVA, with confirmation of effect, was indicate reduce in ∆Lactate (p: 0.001; BFincl: 25.02); absolute AnLa (p: 0.002; BFincl: 12.61), fatigue index (p > 0.001; BFincl: 63.25) and total anaerobic participation (p: 0.008; BFincl: 4.89). CONCLUSIONS: Thus, the results demonstrated that all changes presented were evidenced as a result of exposure to the training period and ß-alanine supplementation doesn't affect metabolic contribution and performance during 400-m freestyle.

Photobiomodulation by light emitting diode applied sequentially does not alter performance in cycling athletes.

Analyze the effects of sequential application of photobiomodulation therapy (PBMT) at different wavelengths on the performance of cycling athletes. Cyclists (48 male, mean age 33.77 years) underwent a performance evaluation through an incremental test, VO2max, blood lactate analysis, perception of effort, infrared thermography, and isokinetic evaluations. Photobiomodulation (180 J) with infrared (IR 940 ± 10 nm), red (RED 620 ± 10 nm), mixed Red, and IR (RED/IR 620 + 940 nm) or Sham (disabled device) intervention occurred on three consecutive days and was applied to the quadriceps femoris bilaterally. Reevaluations were performed 24 h after the last application, with 1 week of follow-up. A significance level of 5% was adopted, and the effect size (ES) was calculated by Cohen's d. Results: There were no significant differences in the analyzed variables under any experimental condition (p > 0.005), but a moderate effect size was observed for torque peak at 60°/s on left lower limb (LLL) (ES = 0.67), average power at 60°/s of the right lower limb (RLL) (0.73), and LLL (ES = 0.65) and a considerable effect size in torque peak at 60°/s of the RLL (ES = 0.98) in the IR/RED group compared with sham 24 h after the last application. Moreover, a large effect size was observed for total time to exhaustion (ES = 1.98) and for VO2max (ES = 6.96), and a moderate effect size was seen for anaerobic threshold (ES = 0.62) in the IR/RED group compared with sham. Photobiomodulation, when not associated with training, was not able to produce a cumulative effect on the performance of cycling athletes. However, the association of two wavelengths seems to be better for increased performance. ClinicalTrials.gov Identifier: NCT03225976.

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.

Uso da estatística na Educação Física: análise das publicações nacionais entre os anos de 2009 e 2011 / Use of statistics in Physical Education: analysis of national publications between 2009 and 2011

O objetivo do presente estudo foi verificar o padrão de uso da estatística em artigos científicos publicados em periódicos nacionais da área da Educação Física. Para tal, foram analisados todos os artigos publicados no triênio 2009-2011 de periódicos da área de Educação Física com estratificação B2 ou superior no QUALIS CAPES (Área 21) vigente. No levantamento bibliográfico foram encontrados 872 artigos nas cinco revistas pesquisadas, que foram classificados em sem estatística, estatística descritiva e estatística analítica. Para as análises, utilizou-se a estatística descritiva e o intervalo de confiança de 95% para comparar a diferença entre as proporções e, quando necessário, o teste qui-quadrado e regressão logística. Observou-se uma menor proporção de trabalhos com análise descritiva (7,1%; IC95% = 5,4%-8,8%) quando comparados com os artigos sem estatística (46,3%; IC95% = 42,9%-49,6%) e com estatística analítica (46,6%; IC95% = 43,2%-49,9%). O padrão de uso de procedimentos estatísticos variou entre as cinco revistas científicas e entre as áreas de concentração (Saúde, Esporte, Lazer, Educação e Outras). A proporção dos artigos que não atenderam aos pressupostos básicos para a utilização de testes paramétricos foi de 43,3%. Essa proporção não apresentou diferença significativa ao longo dos três anos analisados, região de afiliação dos primeiros e últimos autores ou em relação à titulação dos primeiros e últimos autores. O presente estudo aponta um cenário preocupante no que tange à utilização da estatística na área de Educação Física, pois, além do alto índice de trabalhos que não seguem os pressupostos básicos para utilização da estatística, essa situação parece ser comum independente da titulação dos autores, região de afiliação ou revista de publicação.

The purpose of the present study was to verify the pattern of use of statistics in scientific articles published in national journals of the Physical Education area. Thus, all articles published in the 2009-2011triennium of the Physical Education journals stratified at B2 or higher in the current QUALIS CAPES (Field 21) were analyzed. The bibliographic search found 872 articles in the five journals selected, which were classified into no statistics, descriptive statistics and analytical statistics. For the analysis, descriptive statistics was performed and the 95% confidence interval to compare the difference between the proportions and, when necessary, the chi-square test and Logistic Regression. There was a lower proportion of articles with descriptive analysis (7.1%, 95%CI=5.4%-8.8%) compared with those with no statistics (46.3%, 95%CI=42.9%-49.6%) and analytical statistics (46.6%, 95%CI=43.2%-49.9%). The pattern of use of statistical procedures ranged among the five scientific journals and across fields of concentration (Health, Sport, Leisure, Education and Others). The proportion of articles which did not meet the basic assumptions for the use of parametric test was 43.3%. This proportion was not significantly different over the three years analyzed, first and last authors' region of affiliation of or for the first and last authors' degree. The present study points out a worrying scenario regarding the use of statistics in the area of Physical Education, because besides the high amount of work which do not follow the basic assumptions for statistical use , this situation seems to be common regardless of authors' degree, region of affiliation or journal of publication.

Efeito das cargas de treinamento sobre parâmetros fisiológicos de futebolistas / Effect of training loads on physiological parameters of soccer players

O objetivo desse estudo foi verificar os efeitos de três semanas de treinamentos com intensidades monitoradas sobre a capacidade aeróbia de futebolistas profissionais. Quatorze futebolistas integrantes de equipe da primeira divisão do Campeonato Brasileiro de 2010, foram avaliados pré e pós três semanas de treinamento. O limiar anaeróbio (LAn) foi determinado pelo método bi-segmentado, para isso quatro esforços submáximos de 800 metros com intensidades de 10, 12, 14 e 16 km/h foram aplicados. Trinta três sessões de treinamentos foram quantificadas em zonas de acordo com frequência cardíaca referente ao LAn (FC LAn): Z1 - 10% abaixo, Z2 - 90-100% e Z3 - acima da FC LAn. Durante os treinamentos os jogadores permaneceram 31,17±14,86%, 42,96±14,90% e 25,87±16,67% em Z1, Z2 e Z3, respectivamente. Não foram encontradas diferenças significativas no LAn (pré = 13,29 ± 0,71 km∙h-1; pós=12,85 ± 0,90 km∙h-1), percepção subjetiva de esforço correspondente ao LAn (pré = 11,53 ± 1,45 u.a; pós=11,23 ± 1,53 u.a) e FC LAn (pré = 166,64 ± 10,69 bpm; pós = 174,50 ± 10,89 bpm), indicando que três semanas de treinamento são insuficiente para gerar adaptações positivas no LAn de futebolistas.

The aim of this study was to investigate the effects of three weeks of training with intensity monitored on the aerobic capacity of professional soccer players. Fourteen players, members of a first division Brazilian Championship team in 2010, aged 22.78 ± 3.06 years were evaluated pre and post three weeks of training. The anaerobic threshold intensity LAn was determined by bi-segmented method, for this four submaximal efforts of 800 meters with intensities 10, 12, 14 and 16 km/h were applied. Thirty three training sessions were quantified in zones according to heart rate related to the LAn (FC LAn): Z1 - 10% below, Z2 - 90-100% and Z3 - above the FC LAn. During training participants remained 31.17 ± 14.86%, 42.96% and 25.87 ± 14.90 ± 16.67% in Z1, Z2, and Z3 respectively. There were no significant differences in the LAn (pre = 13,29 ± 0,71 km∙h-1; post = 12,85 ± 0,90 km∙h-1), perceived exertion (pre = 11,53 ± 1,45 u.a; post = 11,23 ± 1,53 u.a) and FC LAn (pre = 166,64 ± 10,69 bpm; post = 174,50 ± 10,89 bpm) between conditions before and after training, indicating that three weeks of training are insufficient to generate positive changes in soccer players LAn.