Use of Inter-Effort Recovery Hypoxia as a New Approach to Improve Anaerobic Capacity and Time to Exhaustion.

Putti, Germano Marcolino, Gabriel Peinado Costa, Matheus Silva Norberto, Carlos Dellavechia de Carvalho, Rômulo Cássio de Moraes Bertuzzi, and Marcelo Papoti. Use of inter-effort recovery hypoxia as a new approach to improve anaerobic capacity and time to exhaustion. High Alt Med Biol. 25:68-76, 2024. Background: Although adding hypoxia to high-intensity training may offer some benefits, a significant problem of this training model is the diminished quality of the training session when performing efforts in hypoxia. The purpose of this study was to investigate the effects of training and tapering combined with inter-effort recovery hypoxia (IEH) on anaerobic capacity, as estimated by alternative maximum accumulated oxygen deficit (MAODALT) and time to exhaustion (TTE). Methods: Twenty-four amateur runners performed, for 5 weeks, 3 sessions per week of training consisted of ten 1-minute bouts at 120% (weeks 1-3) and 130% (weeks 4 and 5) of maximum velocity (VMAX) obtained in graded exercise test, separated by a 2-minute interval in IEH (IEH, n = 11, FIO2 = 0.136) or normoxia (NOR, n = 13, fraction of inspired oxygen = 0.209). Before training, after training, and after 1 week of tapering, a graded exercise test and a maximal effort to exhaustion at 120% of VMAX were performed to determine TTE and MAODALT. The results were analyzed using generalized linear mixed models, and a clinical analysis was also realized by the smallest worthwhile change. Results: MAODALT increased only in IEH after training (0.8 ± 0.5 eq.lO2) and tapering (0.8 ± 0.5 eq.lO2), with time x group interaction. TTE increased for the pooled groups after taper (23 ± 11 seconds) and only for IEH alone (29 ± 16 seconds). Clinical analysis revealed a small size increase for NOR and a moderate size increase for IEH. Conclusions: Although the effects should be investigated in other populations, it can be concluded that IEH is a promising model for improving anaerobic performance and capacity. World Health Organization Universal Trial Number: U1111-1295-9954. University's ethics committee registration number: CAAE: 32220020.0.0000.5659.

Metformin anticipates peak of lactate during high-intensity interval training but no changes performance or neuromuscular response in amateur swimmers.

BACKGROUND & AIMS: Metformin demonstrated potential to improve metabolic efficiency in short-intense and prolonged-continuous efforts. The present study investigates the acute effects of metformin intake on performance, rating of perceived exertion (RPE), blood lactate, blood glucose and neuromuscular parameters related to swimming high-intensity interval series. METHODS: A double-blind, crossover, randomized and placebo-controlled study was carried out. Seven healthy swimmers ingested metformin (500 mg) or placebo capsules on different days and performed a typical high-intensity training series (10 bouts of 50 m with a 3-min interval). Performance, RPE, neuromuscular parameters (lower and upper limbs), blood lactate and glucose were analyzed by the Wilcoxon Signed-Rank and Friedman's tests between supplementation situations and moments, respectively (p > 0.05), the moment where glucose and blood lactate peak were found were analyzed by a Student t-test (p > 0.05) and a Bayesian repeated-measures ANOVA for effects analysis (BFincl). RESULTS: The anticipation of blood glucose and peak lactate was signaling by the interaction effect (metformin increased and placebo decreased) between the eighth and the last bout (BFincl: 4.230 and 5.188 respectively). The second interaction effect of blood glucose and lactate (metformin maintained and placebo increased) during recoveries between 5 min and 7 min (BFincl: 3.825 and 3.806 respectively) also signaling the anticipatory behavior of both physiological parameters. The anticipation of blood lactate peak concentration after metformin intake confirms the anticipatory behavior of blood lactate (p: 0.015). CONCLUSIONS: The anticipatory behavior of glucose was not confirmed. Although the anticipatory peak of blood lactate, metformin does not affect neuromuscular responses, RPE and performance. REGISTRATION OF CLINICAL TRIAL: RBR-67wxdw8 Effects of metformin during swimmer training performance.

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.

A New Approach to Evaluate Neuromuscular Fatigue of Extensor Elbow Muscles.

Neuromuscular fatigue evaluation is widely performed on different muscles through the conventional protocol using maximum voluntary contraction (MVC) with electrical stimuli in the analyzed muscle. In an attempt to use this protocol on elbow extensor musculature, previous studies and pilot studies showed co-contraction effects from antagonist musculature during muscular stimulations. The aim of this study was to propose a new neuromuscular fatigue protocol evaluation on elbow extensor musculature. Twenty participants preformed exercises to induce central (CenFat) and peripheral fatigue (PerFat). Neuromuscular fatigue was evaluated on knee extensor muscles by a conventional protocol that provides Twitch Superimposed (TSK) and Twitch Potentiated (TPK), central and peripheral parameters respectively. For elbow extensor muscles, the protocol used sustained submaximal contraction at 10, 20, 30, 40, and 50% of MVC. The neuromuscular fatigue in upper limbs was identified by Twitch Potentiated (TPE) and multiple Twitch Superimposed (TSE) parameters. Using the relationship between MVC (%) and evoked force, the proposed protocol used several TSE to provide slope, y-intercept and R 2. It is proposed that slope, R 2, and y-intercept change may indicate peripheral fatigue and the identified relationship between y-intercept and R 2 may indicate central fatigue or both peripheral and central fatigue. The results were compared using the non-parametric analyzes of Friedmann and Wilcoxon and their possible correlations were verified by the Spearmann test (significance level set at p < 0.05). After PerFat a decrease in TPE (57.1%, p < 0.001) was found but not in any TSE, indicating only peripheral fatigue in upper limbs. After CenFat a decrease in TPE (21.4%, p: 0.008) and TPK (20.9%, p < 0.001) were found but not in TSK, indicating peripheral fatigue in upper and lower limbs but not central fatigue. A non-significant increase of 15.3% after CenFat and a statistical reduction (80.1%, p: 0.001) after PerFat were found by slope. Despite R 2 showing differences after both exercises (p < 0.05), it showed a recovery behavior after CenFat (p: 0.016). Although PerFat provided only peripheral fatigue, CenFat did not provide central fatigue. Considering the procedural limitations of CenFat, parameters resulting from the proposed protocol are sensitive to neuromuscular alteration, however, further studies are required.

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.

Relações entre flexibilidade de membros inferiores e índice de lesões em modalidades de resistência / Lower limb flexibility and injury index relationship on resistance modalities / Relación entre la flexibilidad de los miembros inferiores y el índice de lesiones en las modalidades de resistencia

Resumo O objetivo deste estudo transversal foi analisar as possíveis relações entre a flexibilidade de membros inferiores com histórico de lesões em modalidades de resistência: ciclismo, corrida, natação e triathlon. Vinte atletas de cada modalidade foram submetidos a um questionário e posteriormente a uma avaliação da flexibilidade por meio da goniometria que investigaram articulações que compreendem movimentação de quadril, joelho e tornozelo. Foram encontradas relações significantes entre a flexibilidade e o histórico de lesões. Essas relações foram positivas para corrida e triathlon e negativa para corrida. Também foi evidenciado que a flexibilidade específica de algumas porções referente a membros inferiores tem relações positivas e negativas com o histórico de lesão em regiões específicas do corpo. Conclui-se que a flexibilidade pode ter tido influência no histórico lesivo do praticante e essa relação é diferente entre modalidades de resistência.

Abstract The aim of this cross-section study was to analyze the possible relationships between lower limb flexibility and injury history in resistance modalities: cycling, running, swimming and triathlon. Twenty athletes of each modality were submitted to a questionnaire and later to an evaluation of flexibility through goniometry, investigating joints that comprise movement of: hip, knee and ankle. Significant relationships between flexibility and the history of injuries were found. Being the positive relations for running and triathlon and negative for running. It has also been shown that the specific flexibility of some portions regarding lower limbs has positive and negative relationships with the injury history in specific regions of the body. It is concluded that flexibility may have had an influence on the practitioner's harmful history and this relationship is different between modalities of resistance.

Resumen El objetivo de este estudio transversal fue analizar las posibles relaciones entre la flexibilidad de los miembros inferiores y un historial de lesiones en modalidades de resistencia: ciclismo, atletismo, natación y triatlón. Veinte atletas de cada modalidad respondieron a un cuestionario y, posteriormente, se valoró su flexibilidad por medio de goniometría, para analizar las articulaciones que implican un movimiento de cadera, rodilla y tobillo. Se encontraron relaciones importantes entre la flexibilidad y el historial de lesiones. Estas relaciones fueron positivas en el atletismo y el triatlón, y negativas en el atletismo. También se puso de manifiesto que la flexibilidad específica de algunas partes de los miembros inferiores tiene relaciones positivas y negativas con el historial de lesión en regiones específicas del miembro inferior. Se concluye que la flexibilidad puede haber influido en el historial lesivo del deportista y esta relación es diferente en función de la modalidad de resistencia.