ß-Alanine Plus Sodium Bicarbonate Co-Supplementation Does Not Decrease Neuromuscular Fatigue in Swimming.

This study aimed to investigate the effects of chronic ß-alanine (ßA) plus acute sodium bicarbonate (SB) co-supplementation on neuromuscular fatigue during high-intensity intermittent efforts in swimming. Eleven regional and national competitive-level young swimmers performed a neuromuscular fatigue assessment before and immediately after two 20 × 25-m front crawl maximal efforts every 90 s, performed at pre- and post-4-week co-supplementation. Neuromuscular fatigue was evaluated by percutaneous electrical stimuli through the twitch interpolation technique on the triceps brachii and quadriceps femoris. Performance was defined by the mean time of the 20 efforts and blood samples to lactate concentrations were collected every four efforts. Participants supplemented 3.2-6.4 g·day-1 of chronic ßA or placebo (PL) during four weeks, and acute 0.3 g·kg-1 of SB or PL 60 min before the second assessment (allowing ßA+SB and PL+PL groups). No statistical changes were found in neuromuscular fatigue of triceps brachii. In the quadriceps femoris, a main effect of time was found in potentiated twitch delta values in pooled groups, showing a statistical increase of 19.01% after four weeks (Δ = 13.05 [0.35-25.75] N; p = 0.044), without time × group interactions. No statistical difference was found in the swimming performance. Blood lactate increased by 25.06% only in the ßA+SB group (Δ = 6.40 [4.62-8.18] mM; p Bonf < 0.001) after the supplementation period. In conclusion, 4-week ßA and SB co-supplementation were not able to reduce neuromuscular fatigue levels and improve performance in highintensity intermittent efforts, but statistically increased blood lactate levels.

Four-week experimental plus 1-week taper period using live high train low does not alter muscle glycogen content.

This study aimed to investigate the effects of a 4-week live high train low (LHTL; FiO2 ~ 13.5%), intervention, followed by a tapering phase, on muscle glycogen concentration. Fourteen physically active males (28 ± 6 years, 81.6 ± 15.4 kg, 179 ± 5.2 cm) were divided into a control group (CON; n = 5), and the group that performed the LHTL, which was exposed to hypoxia (LHTL; n = 9). The subjects trained using a one-legged knee extension exercise, which enabled four experimental conditions: leg training in hypoxia (TLHYP); leg control in hypoxia (CLHYP, n = 9); leg trained in normoxia (TLNOR, n = 5), and leg control in normoxia (CLNOR, n = 5). All participants performed 18 training sessions lasting between 20 and 45 min [80-200% of intensity corresponding to the time to exhaustion (TTE) reached in the graded exercise test]. Additionally, participants spent approximately 10 h day-1 in either a normobaric hypoxic environment (14.5% FiO2; ~ 3000 m) or a control condition (i.e., staying in similar tents on ~ 530 m). Thereafter, participants underwent a taper protocol consisting of six additional training sessions with a reduced training load. SpO2 was lower, and the hypoxic dose was higher in LHTL compared to CON (p < 0.001). After 4 weeks, glycogen had increased significantly only in the TLNOR and TLHYP groups and remained elevated after the taper (p < 0.016). Time to exhaustion in the LHTL increased after both the 4-week training period and the taper compared to the baseline (p < 0.001). Although the 4-week training promoted substantial increases in muscle glycogen content, TTE increased in LHTL condition.

Cardiopulmonary exercise test in type 2 diabetes mellitus in absence of chronic heart failure: reduced lung and heart function / Avaliação cardiopulmonar em portadores de diabetes melitus tipo 2 sem doença cardíaca: redução da função caridorespiratória

Was compared exercise tolerance, respiratory and cardiovascular functions between non--diabetics and type 2 diabetics individuals (T2DM) without chronic heart failure. Thirteen normaglycemic men (non-diabetic group ­ NDG) and eight T2DM (diabetic group ­ DG) performed a cardiopulmonary exercise test (CPX) on motor treadmill (test initiated at 3 km.h-1 with an increment of 1 km.h-1 every two minutes) to evaluate respiratory function, cardiovascular parameters and exercise tolerance. Workload and oxygen uptake ( O2) values at ventilatory threshold were signifi cantly lower for DG (DG: 5.6 ± 0.5 km/h and 13.1 ± 3.8 mL.(kg.min)-1; NDG: 6.5 ± 0.5 km/h and 16.4 ± 2.8 mL.(kg.min)-1; p < 0.05). Peak O2 and workload were signifi cantly lower for DG (22.7 ± 5.7 mL.(kg.min)-1;8.2 ± 0.7 km/h) when compared with NDG (30.8 ± 5.4 mL.(kg.min)-1; 11.6 ± 1.5 km/h). Oxygen uptake effi ciency slope (OUES) and circulatory power were signifi cantly lower (p < 0.05) in DG, although no signifi cant alterations were found in functional capacity and ventilatory effi ciency. T2DM in absence of chronic heart failure presented exercise intolerance and lower cardiorespiratory fi tness. Peak circulatory power and OUES were also reduced in these individuals....(AU)

Foi comparar a tolerância ao exercício, funções respiratória e cardiovascular entre indivíduos não diabéticos e diabéticos tipo 2 sem doenças crônicas cardíacas. Treze homens normoglicêmicos (NDG) e oito homens diabéticos tipo 2 (DG) que realizaram um teste cardiopulmonar de esforço (TCPE) em uma esteira motorizada (o teste iniciou-se em 3km.h-1 com incremento de 1km.h-1 a cada dois minutos) que avaliou a função respiratória, parâmetros cardiovasculares e tolerância ao exercício. Valores de consumo de oxigênio e intensidades na intensidade do limiar ventilatório foram signifi cativamente menores para o DG (DG: 5,6 ± 0,5 km/h-1 e 13,1 ± 3,8 ml.(kg.min)-1; NDG: 6,5 ± 0,5 km/h-1 e 16,4 ± 2,8 ml.(kg.min)-1; p < 0,05). Consumo de oxigênio pico e intensidade associada foram signifi cativamente menores para o DG (DG: 22,7 ± 5,7 ml.(kg.min)-1; 8,2 km/h-1 ± 0,7 km/h-1) quando comparado com o NDG (30,8 ± 5,4 ml.(kg.min)-1; 11,6 ± 1,5 km/h). Oxygen uptake effi ciency slope (OUES) e circulatory power foram signifi cativamente menores para o DG (p < 0,05) embora não foram encontradas diferenças signifi cativas na efi ciência ventilatória. Em indivíduos portadores de diabetes tipo 2, mesmo sem a presença conhecida de doenças cardiovasculares, apresentaram menores níveis de condicionamento cardiorrespiratório e tolerância ao exercício. Circulatory power pico e OUES também foram reduzidos nesses indivíduos....(AU)