Comparison of carbohydrate and milk-based beverages on muscle damage and glycogen following exercise.
ABSTRACT This study examined effects of carbohydrate (CHO), milk-based carbohydrate-protein (CHO-PRO), or placebo (P) beverages on glycogen resynthesis, muscle damage, inflammation, and muscle function following eccentric resistance exercise. Untrained males performed a cycling exercise to reduce muscle glycogen 12 hours prior to performance of 100 eccentric quadriceps contractions at 120% of 1-RM (day 1) and drank CHO (n = 8), CHO-PRO (n = 9; 5 kcal/kg), or P (n = 9) immediately and 2 hours post-exercise. At 3 hours post-eccentric exercise, serum insulin was four times higher for CHO-PRO and CHO than P (p < .05). Serum creatine kinase (CK) increased for all groups in the 6 hours post-eccentric exercise (p < .01), with the increase tending to be lowest for CHO-PRO (p < .08) during this period. Glycogen was low post-exercise (33+/-3.7 mmol/kg ww), increased 225% at 24 hours, and tripled by 72 hours, with no group differences. The eccentric exercise increased muscle protein breakdown as indicated by urinary 3-methylhistidine and increased IL-6 with no effect of beverage. Quadriceps isokinetic peak torque was depressed similarly for all groups by 24% 24 hours post-exercise and remained 21% lower at 72 hours (p < .01). In summary, there were no influences of any post-exercise beverage on muscle glycogen replacement, inflammation, or muscle function.
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ABSTRACT: Unaccustomed high-intensity eccentric exercise (ECC) can provoke muscle damage including several days of muscle force loss. Post-exercise dietary supplementation may provide a strategy to accelerate rate of force regain by affecting mechanisms related to muscle protein turnover. The aim of the current study was to investigate if protein signaling mechanisms involved in muscle protein turnover would be differentially affected by supplementation with either whey protein hydrolysate and carbohydrate (WPH+CHO) versus isocaloric carbohydrate (CHO) after muscle-damaging ECC. Twenty-four young healthy participants received either WPH+CHO (n = 12) or CHO supplements (n = 12) during post-exercise recovery from 150 maximal unilateral eccentric contractions. Prior to, at 3 h and at 24, 48, 96 and/or 168 h post-exercise, muscle strength, muscle soreness, and Akt-mTOR and FOXO signaling proteins, were measured in an ECC exercising leg and in the contralateral non-exercise control leg (CON). After ECC, muscle force decreased by 23–27 % at 24 h post-exercise, which was followed by gradual, although not full recovery at 168 h post-exercise, with no differences between supplement groups. Phosphorylation of mTOR, p70S6K and rpS6 increased and phosphorylation of FOXO1 and FOXO3 decreased in the ECC leg, with no differences between supplement groups. Phosphorylation changes were also observed for rpS6, FOXO1 and FOXO3a in the CON leg, suggesting occurrence of remote tissue effects. In conclusion, divergent dietary supplementation types did not produce differences in signaling for muscle turnover during recovery from muscle-damaging exercise.Amino Acids 01/2015; 47(4). DOI:10.1007/s00726-014-1907-8 · 3.65 Impact Factor
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ABSTRACT: Background: Several studies on Caucasian volunteers have proven that milk is an effective recovery drink for athletes. Such benefit, however, cannot be directly applied to the lactose-intolerant Asian population. This study investigated the effects of ingesting water (WT), sports drink (SPD) and lactose-free milk (LFM) on cycling capacity. Methods: Ten healthy young men completed 3 randomized experimental trials. Each trial consisted of an intermittent glycogen depleting session, a 2 h recovery period during which they ingested the test drink, followed by cycling at 70% of their maximum oxygen consumption (VO(2)max) to volitional exhaustion. Each trial was separated by at least one week. Results: There were no complaints or symptoms of lactose intolerance during any of the trials. The cycling periods were different (p < 0.05) amongst the 3 trials, namely, lactose-free milk (LFM; 69.6 +/- 14.0 min), sports drink (SPD; 52.1 +/- 11.6 min), and water (WT; 36.0 +/- 11.1 min), respectively. The VO2 and VCO2 of LFM (30 +/- 4 and 29 +/- 4 ml/kg/min) were lower (p < 0.05) than that of SPD (34 +/- 4 and 34 +/- 4 ml/kg/min) and WT (35 +/- 4 and 33 +/- 5 ml/kg/min). There were no differences (p = 0.45) in VO2 and VCO2 between SPD and WT. Mean rating of perceived exertion was lowest in LFM (14 +/- 5; p < 0.05), while no difference was found between the other two trials (SPD: 16 +/- 4 and WT: 16 +/- 4; p = 0.18). Conclusion: Lactose-free milk is likely to be an effective recovery drink for enhancing subsequent cycling capacity in lactose intolerant Asian males.Journal of the International Society of Sports Nutrition 10/2014; 11(1):49. DOI:10.1186/s12970-014-0049-4 · 1.50 Impact Factor