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: Following a 2.0 +/- 0.1% body mass loss induced by intermittent exercise in the heat, seven male volunteers ingested either a carbohydrate-electrolyte solution (CE) or skimmed milk (M) in a volume equal to 150% of body mass loss. At the end of the 3 h recovery period, subjects were essentially in positive fluid balance on trial M (191 +/- 162 mL), and euhydrated on trial CE (-135 +/- 392 mL) despite being in negative sodium balance on both trials and negative potassium balance on trial CE. This difference of 326 +/- 354 mL or 0.4% body mass approached significance (P = 0.051). Subjects ingested 137 +/- 15 and 113 +/- 12 g of CHO during the CE and M trials, respectively, as well as 75 +/- 8 g of protein during the M trial. At the end of the 3 h recovery period, an exercise capacity test was completed at 61% VO(2peak) in warm (35.3 +/- 0.5 degrees C), humid (63 +/- 2%) conditions. HR (P = 0.020) and rectal temperature (P = 0.045) were higher on trial M, but no difference in exercise time to exhaustion was observed between trials (39.6 +/- 7.3 min vs. 39.7 +/- 8.1 min on trials CE and M, respectively). The results of the present study suggest that milk can be an effective post-exercise rehydration drink, with subjects remaining in net positive fluid balance throughout the recovery period. Despite the effect on fluid retention, exercise capacity was not different between skimmed milk and a commercially available carbohydrate-electrolyte drink 4 h following exercise/heat-induced body mass loss.Arbeitsphysiologie 08/2008; 104(4):633-42. DOI:10.1007/s00421-008-0809-4 · 2.30 Impact Factor
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ABSTRACT: The present study examined the effects of adding leucine to pre and postexercise carbohydrate beverages on selected markers of muscle damage, delayed-onset muscle soreness (DOMS), and squat performance for up to 72 hours after lower-body resistance training. Seventeen resistance trained men (mean +/- SD age 22.9 +/- 2.9 years) and 3 resistance trained women (mean +/- SD age 21.6 +/- 2.6 years) performed 6 sets of squats to fatigue using 75% of the 1 repetition maximum. Each subject consumed a carbohydrate beverage 30 minutes before and immediately after exercise with or without the addition of 22.5 mgxkg (45 mgxkg total) of leucine in a randomized, double-blind fashion. Serum creatine kinase (CK), lactate dehydrogenase (LDH), and DOMS were analyzed immediately before (TIME1), 24 (TIME2), 48 (TIME3), and 72 (TIME4) hours after exercise. The subjects repeated the squat protocol at TIME4 to test recovery. No differences were observed between groups for squat performance, defined as the total number of repetitions performed during 6 sets of squats, for both TIME1 and TIME4. The addition of leucine did not significantly decrease CK and LDH activity or DOMS. These results suggested that adding leucine to carbohydrate beverages did not affect acute muscle recovery and squat performance during both initial testing and during a subsequent exercise bout 72 hours later in resistance trained subjects.The Journal of Strength and Conditioning Research 08/2010; 24(8):2211-9. DOI:10.1519/JSC.0b013e3181dc3a10 · 1.86 Impact Factor
- Medicine & Science in Sports & Exercise 04/2004; 36(5):S126. DOI:10.1249/00005768-200405001-00600 · 4.46 Impact Factor