Training in the fasted state facilitates re-activation of eEF2 activity during recovery from endurance exercise.
ABSTRACT Nutrition is an important co-factor in exercise-induced training adaptations in muscle. We compared the effect of 6 weeks endurance training (3 days/week, 1-2 h at 75% VO(2peak)) in either the fasted state (F; n = 10) or in the high carbohydrate state (CHO, n = 10), on Ca(2+)-dependent intramyocellular signalling in young male volunteers. Subjects in CHO received a carbohydrate-rich breakfast before each training session, as well as ingested carbohydrates during exercise. Before (pretest) and after (posttest) the training period, subjects performed a 2 h constant-load exercise bout (~70% of pretest VO(2peak)) while ingesting carbohydrates (1 g/kg h(-1)). A muscle biopsy was taken from m. vastus lateralis immediately before and after the test, and after 4 h of recovery. Compared with pretest, in the posttest basal eukaryotic elongation factor 2 (eEF2) phosphorylation was elevated in CHO (P < 0.05), but not in F. In the pretest, exercise increased the degree of eEF2 phosphorylation about twofold (P < 0.05), and values returned to baseline within the 4 h recovery period in each group. However, in the posttest dephosphorylation of eEF2 was negated after recovery in CHO, but not in F. Independent of the dietary condition training enhanced the basal phosphorylation status of Phospholamban at Thr(17), 5'-AMP-activated protein kinase α (AMPKα), and Acetyl CoA carboxylase β (ACCβ), and abolished the exercise-induced increase of AMPKα and ACCβ (P < 0.05). In conclusion, training in the fasted state, compared with identical training with ample carbohydrate intake, facilitates post-exercise dephosphorylation of eEF2. This may contribute to rapid re-activation of muscle protein translation following endurance exercise.
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ABSTRACT: Diet can significantly influence athletic performance, but recent research developments have substantially changed our understanding of sport and exercise nutrition. Athletes adopt various nutritional strategies in training and competition in the pursuit of success. The aim of training is to promote changes in the structure and function of muscle and other tissues by selective modulation of protein synthesis and breakdown in response to the training stimulus. This process is affected by the availability of essential amino acids in the post-exercise period. Athletes have been encouraged to eat diets high in carbohydrate, but low-carbohydrate diets up-regulate the capacity of muscle for fat oxidation, potentially sparing the limited carbohydrate stores. Such diets, however, do not enhance endurance performance. It is not yet known whether the increased capacity for fat oxidation that results from training in a carbohydrate-deficient state can promote loss of body fat. Preventing excessive fluid deficits will maintain exercise capacity, and ensuring adequate hydration status can also reduce subjective perception of effort. This latter effect may be important in encouraging exercise participation and promoting adherence to exercise programmes. Dietary supplement use is popular in sport, and a few supplements may improve performance in specific exercise tasks. Athletes must be cautious, however, not to contravene the doping regulations. There is an increasing recognition of the role of the brain in determining exercise performance: various nutritional strategies have been proposed, but with limited success. Nutrition strategies developed for use by athletes can also be used to achieve functional benefits in other populations.Proceedings of The Nutrition Society 02/2012; 71(1):112-9. · 3.67 Impact Factor
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ABSTRACT: PURPOSE- In this study we compared the effect of sprint interval training (SIT) in normoxia versus hypoxia on muscle glycolytic and oxidative capacity, monocarboxylate transporter (MCT) content, and endurance exercise performance. Methods - Healthy male volunteers (18-30 yrs) performed 6 weeks of SIT on a cycling ergometer (30s sprints vs. 4.5min rest intervals; 3d/wk) in either normobaric hypoxia (HYP, FiO2=14.4%, n=10) or in normoxia (NOR, FiO2=20.9%, n=9). The control group did not train (CON, n=10). Training load was increased from 4 sprints per session in week-1 to 9 sprints in week-6. Before and after SIT subjects performed a maximal incremental exercise test plus a 10min simulated time trial on a cycle ergometer in both normoxia (MAXnor, TTnor) and hypoxia (MAXhyp, TThyp). A needle biopsy was taken from m.vastus lateralis at rest 5-6 days post the last exercise session. Results - SIT increased muscle phosphofructokinase activity more in HYP (+59%, p<0.05) than in NOR (+17%), whilst citrate synthase activity was similar between groups. Compared with the pretest, power outputs corresponding to 4 mmol blood lactate in HYP during MAXnor (+7%) and MAXhyp (+9%) were slightly increased (p<0.05), whilst values were constant in NOR. VO2max in MAXnor and TT performance in TTnor and TThyp were increased by ~5-7% (p<0.05) in either group. The training elevated MCT1 protein content by ~70%, (p<0.05). In CON all measurements were constant throughout the study. Conclusion - SIT in hypoxia upregulated muscle phosphofructokinase activity and the anaerobic threshold more than SIT in normoxia, but did not enhance endurance exercise performance.Medicine and science in sports and exercise 04/2013; · 3.71 Impact Factor
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ABSTRACT: To examine the time-of-day and Ramadan fasting (RF) effects on serum apolipoprotein-AI (Apo-AI) and B (Apo-B), lipoprotein particles-a (Lp-a), high-sensitive C-reactive-protein (hs-CRP), and homocysteine (Hcy) during the Yo-Yo intermittent recovery test (YYIRT). Performance and biochemical measures were completed at two times-of-day (07:00 and 17:00 h), 1-week before RF (BR), the second week of RF (SWR), and the fourth week of RF (ER). For each session, subjects performed the YYIRT, and blood samples were taken before and 3-min after the test for biochemical measures. Fifteen soccer players. Total distance during the YYIRT, core temperature, body composition, dietary intakes, lipid (HDL-C, LDL-C, Apo-AI, B and Lp-a) and inflammatory (hs-CRP and Hcy) profiles. Performances during the YYIRT were higher in the evening than the morning BR (P < 0.05), but this fluctuation was not observed during RF. Moreover, LDL-C, ApoB, and Lp-a were stable throughout the daytime BR. However, during RF, they decreased at 17:00 h (P < 0.05). Likewise, HDL-C and Apo-AI increased after the exercise and were higher at 17:00 h BR (P < 0.001). Moreover, these parameters increased during RF (P < 0.01). Furthermore, Hcy and hs-CRP increased during the exercise (P < 0.01) with higher evening levels BR. During ER, the diurnal pattern of Hcy was inversed (P < 0.001). This study concluded that caloric restriction induced by RF seems to ameliorate lipid and inflammatory markers of cardiovascular health during intermittent exercise performed in the evening.PLoS ONE 01/2013; 8(11):e79873. · 3.73 Impact Factor