Ilex paraguariensisA. St.-Hil. (Yerba Mate) Differently Regulates the Lipid Mobilization and, Irisin and Lactate Levels in Sedentary and Chronic Swimming Mice

Healthy mice were submitted or not to daily chronic swimming and/or daily yerba mate (YM) infusion intake and had their bloods analyzed after four weeks. We hypothesized that daily intake of YM may act differently on lipid mobilization and, on the creatine, lactate and irisin levels in sedentary mice and those submitted to chronic exercise. The groups were (n=48): YM-non-treated control (NTC), YM-non-treated swimming control (NSC), non-roasted YM (NRY), roasted YM (RY), swimming plus non-roasted YM (SNRY), swimming plus roasted YM (SRY). No significant (P>0.05) difference was observed concerning creatine phosphoskinase (CPK) value. Lactate level decreased significantly (P<0.05) for SNRY and SRY, suggesting accelerated lipid mobilization and glycogen sparing potential. There was significant (P<0.05) body weight loss in all, except for NTC. Higher weight loss in NRY, RY, SNR and SRY indicated greater lipid mobilization. Thiobarbituric acid reactive substances (TBARS) and irisin had significantly (P<0.05) higher values for RY. This is first report that deals with the effect of YM consumption on serum irisin level. Major amounts of caffeic acid derivatives, slightly increased caffeine and less amount of rutin may be responsible by accelerated lipoperoxidation in sedentary healthy mices chronically treated with roasted YM. Chronically consumed YM plus swimming aid in healthy weight loss. Sedentary lifestyle plus roasted YM chronic consumption may cause accelerated lipid mobilization and increased TBARS production via irisin overexpression leading to an increase in lipoperoxidation.

Carbohydrate Hydrogel Products Do Not Improve Performance or Gastrointestinal Distress During Moderate-Intensity Endurance Exercise

The benefits of ingesting exogenous carbohydrate (CHO) during prolonged exercise performance are well established. A recent food technology innovation has seen sodium alginate and pectin included in solutions of multiple transportable CHO, to encapsulate them at pH levels found in the stomach. Marketing claims include enhanced gastric emptying and delivery of CHO to the muscle with less gastrointestinal distress, leading to better sports performance. Emerging literature around such claims was identified by searching electronic databases; inclusion criteria were randomized controlled trials investigating metabolic and/or exercise performance parameters during endurance exercise >1 hr, with CHO hydrogels versus traditional CHO fluids and/or noncaloric hydrogels. Limitations associated with the heterogeneity of exercise protocols and control comparisons are noted. To date, improvements in exercise performance/capacity have not been clearly demonstrated with ingestion of CHO hydrogels above traditional CHO fluids. Studies utilizing isotopic tracers demonstrate similar rates of exogenous CHO oxidation, and subjective ratings of gastrointestinal distress do not appear to be different. Overall, data do not support any metabolic or performance advantages to exogenous CHO delivery in hydrogel form over traditional CHO preparations; although, one study demonstrates a possible glycogen sparing effect. The authors note that the current literature has largely failed to investigate the conditions under which maximal CHO availability is needed; high-performance athletes undertaking prolonged events at high relative and absolute exercise intensities. Although investigations are needed to better target the testimonials provided about CHO hydrogels, current evidence suggests that they are similar in outcome and a benefit to traditional CHO sources.

Exogenous ketosis impacts neither performance nor muscle glycogen breakdown in prolonged endurance exercise

Exogenous ketosis produced by oral ketone ester ingestion during the early phase of prolonged endurance exercise and against the background of adequate carbohydrate intake neither causes muscle glycogen sparing nor improves performance in the final stage of the event. However, such exogenous ketosis may decrease buffering capacity in the approach of the final episode of the event. Furthermore, ketone ester intake during exercise may reduce appetite immediately after exercise.

Fiber type-specific muscle glycogen sparing due to carbohydrate intake before and during exercise

The effect of carbohydrate intake before and during exercise on muscle glycogen content was investigated. According to a randomized crossover study design, eight young healthy volunteers ( n = 8) participated in two experimental sessions with an interval of 3 wk. In each session subjects performed 2 h of constant-load bicycle exercise (∼75% maximal oxygen uptake). On one occasion (CHO), they received carbohydrates before (∼150 g) and during (1 g·kg body weight−1·h−1) exercise. On the other occasion they exercised after an overnight fast (F). Fiber type-specific relative glycogen content was determined by periodic acid Schiff staining combined with immunofluorescence in needle biopsies from the vastus lateralis muscle before and immediately after exercise. Preexercise glycogen content was higher in type IIa fibers [9.1 ± 1 × 10−2 optical density (OD)/μm2] than in type I fibers (8.0 ± 1 × 10−2 OD/μm2; P < 0.0001). Type IIa fiber glycogen content decreased during F from 9.6 ± 1 × 10−2 OD/μm2 to 4.5 ± 1 × 10−2 OD/μm2 ( P = 0.001), but it did not significantly change during CHO ( P = 0.29). Conversely, in type I fibers during CHO and F the exercise bout decreased glycogen content to the same degree. We conclude that the combination of carbohydrate intake both before and during moderate- to high-intensity endurance exercise results in glycogen sparing in type IIa muscle fibers.

Glycogen sparing effect induced by lipid supplementation in rats submitted to endurance exercise

Diversos estudos relacionam a adoção de dietas hiperlipídicas ao aumento na capacidade de utilização de lipídios e, por conseguinte, à ocorrência do efeito poupador de glicogênio. Além da maior oferta, a qualidade do lipídio oferecido é capaz de alterar sua taxa de oxidação. O objetivo deste estudo foi verificar o efeito da suplementação lipídica com diferentes tipos de óleos sobre a ocorrência do efeito poupador de glicogênio em ratos submetidos ao exercício de “endurance” (60% V 02PiCo Por 60 minutos). Os animais foram divididos em três grupos: grupo controle treinado (CT), grupo treinado suplementado com óleo de fígado de bacalhau (OFBT) e grupo treinado suplementado com óleo de palmiste (OPT). Após o exercício, o conteúdo de glicogênio muscular não diferiu significativamente entre todos os grupos (Gastrocnêmio - CT 0,31 ±0,02, OFBT 0,25 ± 0,02, OPT - 0,26 ± 0,02; Sóleo CT 0,44 ± 0,04, OFBT - 0,39 ± 0,03, OPT - 0,38 ± 0,04 mg. 100 mg' 1 de tecido úmido). O contrário foi observado no estoque hepático de glicogênio. Os grupos suplementados (OFBT 1,21 ± 0,05, OPT 1,02 ± 0,03 mg. 100 mg'1 de tecido úmido) apresentaram uma redução drástica em relação ao CT (2,12 ± 0,14 mg.100 mg' 1 de tecido úmido). Em ratos, conforme demonstrado anteriormente, a redução do conteúdo hepático de glicogênio e a subseqüente hipoglicemia constituem os fatores limitantes para o desempenho; portanto, independentemente do tipo de lipídio oferecido, os animais suplementados apresentaram menor estoque hepático de glicogênio e, conseqüentemente, essa adaptação será deletéria para o desempenho

Skeletal muscle glycogen phosphorylase akinetics: effects of adenine nucleotides and caffeine

This study aimed to determine physiologically relevant kinetic and allosteric effects of Pi, AMP, ADP, and caffeine on isolated skeletal muscle glycogen phosphorylase a (Phos a). In the absence of effectors, Phos a had V max = 221 ± 2 U/mg and K m = 5.6 ± 0.3 mM Pi at 30°C. AMP and ADP each increased Phos a V max and decreased K m in a dose-dependent manner. AMP was more effective than ADP (e.g., 1 μM AMP vs. ADP: V max = 354 ± 2 vs. 209 ± 8 U/mg, and K m = 2.3 ± 0.1 vs. 4.1 ± 0.3 mM). Both nucleotides were relatively more effective at lower Pi levels. Experiments simulating a range of contraction (exercise) conditions in which Pi, AMP, and ADP were used at appropriate physiological concentrations demonstrated that each agent singly and in combination influences Phos a activity. Caffeine (50–100 μM) inhibited Phos a( K m ∼8–14 mM, ∼40–50% reduction in activity at 2–10 mM Pi). The present in vitro data support a possible contribution of substrate (Pi) and allosteric effects to Phos a regulation in many physiological states, independent of covalent modulation of the percentage of total Phos in the Phos a form and suggest that caffeine inhibition of Phos a activity may contribute to the glycogen-sparing effect of caffeine.

Caffeine, Coffee and Ephedrine: Impact on Exercise Performance and Metabolism

This paper addresses areas where there is controversy regarding caffeine as an ergogenic aid and also identifies topics that have not been adequately addressed. It is clear that caffeine, in moderate amounts, can be used orally as an ergogenic aid in aerobic activity lasting for more than 1 min. It increases endurance and speed, but not maximal [Formula: see text] and related parameters. While there are fewer well-controlled studies for resistance exercise, the literature would suggest similar improvements: increased endurance at submaximal tension and power generated in repeated contractions and no change in maximal ability to produce force. It is likely that theophylline (a related methylxanthine) has similar actions and it has been suggested that the combination of caffeine and sympathomimetics may be a more potent erogenic aid. The voids in our understanding of caffeine include the dose (what amount is optimal, what vehicle is used to deliver the drug as well as method, pattern, and mode of administration), the potential side effects (particularly in competitive settings), health implications (insulin resistance and if combined with ephedrine, cardiovascular risks) and mechanisms of action. It appears unlikely that increased fat oxidation and glycogen sparing is the prime ergogenic mechanism.

Effect of fat adaptation and carbohydrate restoration on metabolism and performance during prolonged cycling

For 5 days, eight well-trained cyclists consumed a random order of a high-carbohydrate (CHO) diet (9.6 g · kg−1 · day−1 CHO, 0.7 g · kg−1 · day−1 fat; HCHO) or an isoenergetic high-fat diet (2.4 g · kg−1 · day−1 CHO, 4 g · kg−1 · day−1 fat; Fat-adapt) while undertaking supervised training. On day 6,subjects ingested high CHO and rested before performance testing on day 7 [2 h cycling at 70% maximal O2consumption (SS) + 7 kJ/kg time trial (TT)]. With Fat-adapt, 5 days of high-fat diet reduced respiratory exchange ratio (RER) during cycling at 70% maximal O2 consumption; this was partially restored by 1 day of high CHO [0.90 ± 0.01 vs. 0.82 ± 0.01 ( P < 0.05) vs. 0.87 ± 0.01 ( P < 0.05), for day 1, day 6, and day 7, respectively]. Corresponding RER values on HCHO trial were [0.91 ± 0.01 vs. 0.88 ± 0.01 ( P < 0.05) vs. 0.93 ± 0.01 ( P < 0.05)]. During SS, estimated fat oxidation increased [94 ± 6 vs. 61 ± 5 g ( P < 0.05)], whereas CHO oxidation decreased [271 ± 16 vs. 342 ± 14 g ( P < 0.05)] for Fat-adapt compared with HCHO. Tracer-derived estimates of plasma glucose uptake revealed no differences between treatments, suggesting muscle glycogen sparing accounted for reduced CHO oxidation. Direct assessment of muscle glycogen utilization showed a similar order of sparing (260 ± 26 vs. 360 ± 43 mmol/kg dry wt; P = 0.06). TT performance was 30.73 ± 1.12 vs. 34.17 ± 2.48 min for Fat-adapt and HCHO ( P = 0.21). These data show significant metabolic adaptations with a brief period of high-fat intake, which persist even after restoration of CHO availability. However, there was no evidence of a clear benefit of fat adaptation to cycling performance.