| Objectives:To investigate effects of sports beverages with various composition on the metabolic status of carbohydrate and fat in endurance training, so that theoretical evidence can be referred to during the practical training and competition.Methods:10healthy trained endurance athletes were recruited in this study. Three specific types of sports drink powder mainly contained Low Molecular Carbohydrate (oligosaccharides, L-CHO), High Molecule Carbohydrate (hydrolyzed starch, H-CHO) and whey protein powder with carbohydrate (CHO-Pro, CHO:Pro=4:1) were chosen and diluted into solution with the equal carbohydrate concentration of8%. A man-made sweeten beverage without carbohydrate was chosen as control group (Placebo, Pla). Several characteristics about those solutions such as Osmolality and Liquid Temperature were measured before the sports beverage ingestion protocol was conducted. A double blind, randomized and cross-over study which contained four specific periods was designed. Subjects were asked to intake one of the four drinks in each period. After an overnight fasting, subjects were required to arrive at the laboratory and consumed a standardize breakfast, then rest for1hour. A70%VO2max cycling training for1hour was conducted after rest period. The chosen sports beverage was ingested according to the designed liquid intake protocol before, during and right after the exercise bout. A standardize lunch was provided and6h after the starting point of the first part of exercise, the second one was conducted, during which subjects were asked to pedal the bicycle at the same intensity as that of the first protocol until exhausted. The chosen sports beverage ingestion was done in the same way as during the first trail in the former45min. Vein blood and breathing gas samples were obtained during exercise so as to make further analysis.Results:(1)Both of L-CHO, H-CHO drink with8%carbohydrate concentration possessed a relatively low osmolality in comparison with that of normal intracellular liquid, while the CHO-Pro drink possessed a relatively high osmolality;(2)Blood Glucose and Serum Insulin concentration in groups of L-CHO, H-CHO and CHO-Pro were higher (P<0.05) than that in Pla after exercise was performed for60minutes;(3) After exercise was performed for30minutes, Serum Insulin concentration in CHO-Pro group remained at the same level those in while other groups dropped significantly (P<0.05);(4)Serum β-HB level in Pla group increased significantly (P<0.05) either after training period was performed for30or60minutes;(5)In L-CHO group, fat oxidation rate immediately after60min of the first bout was significantly higher (P<0.05) than that of the second one;(6)The ratio of energy supplied by carbohydrate increased (P<0.05) during the second bout in groups of L-CHO and Pla.Conclusion:(1)Based on the maintaining effect of Serum Insulin concentration throughout the first bout, CHO-Pro sports beverage is possibly beneficial for endogenous carbohydrate reservation during the training period;(2)Ingesting all of those sports beverages containing carbohydrates is likely to have a positive effect on maintaining acid-base balance in body liquid during endurance training;(3)Ingestion of sports beverages with H-CHO or CHO-Pro may be beneficial for endogenous carbohydrate reservation so that enduring performance could be maintain longer than that in this study design. |
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