CARBOHYDRATE RECOMMENDATIONS


A 1994 review by Hargreaves presents an overview of the early research on the role of carbohydrate in the performance of soccer players before, during, and aſter games and intensive training. Hargreaves con- cluded that a prematch diet of at least 55% of total energy as carbohydrate, accompanied by additional carbohydrate consumed during and aſter a match, maximizes liver and muscle glycogen stores and enhanc- es the performance of athletes.126 Te effects of consuming carbohydrate during HIIE have been researched.127-133


More recently Phillips and colleagues demonstrated that ingesting a 6%


Davison and colleagues


demonstrated that 8 mL/kg of a 6% carbohydrate-electrolyte solution consumed 15 minutes prior to HIIE helped maintain higher blood glucose compared with a placebo or no fluid, resulting in delayed fatigue and improved performance.134


carbohydrate-electrolyte solution significantly improves intermittent, high-intensity endurance capacity but not sprint performance of adolescents during intermittent exercise.131 to decline during or following exercise.86,135


Sporting skills have been shown Phillips and colleagues performed a literature review on the ef-


fects of carbohydrate intake on team sport performance. From studies mimicking the demands of team sport and using appropriate methodology, the authors concluded that a carbohydrate supplementation re- sulted in an increase in blood glucose concentration, significantly higher carbohydrate oxidation rates, and attenuated fat oxidation rates and FFA levels in soccer, rugby, and field hockey players.118 Russell and colleagues reported that a 6% sucrose-electrolyte beverage administered during a soccer match


simulation attenuated declining shooting performance with improved shot speed and overall shooting per- formance at the end of the simulation but did not improve precision, success, ball speed, or performance in passing and dribbling. Te carbohydrate beverage did not prevent an exercise-induced glycemic response when exercise was resumed aſter halſtime.132


reduction in blood glucose while players consumed a carbohydrate-electrolyte beverage during team play.136 Despite evidence that blood glucose concentrations can be maintained beyond 90 minutes and during 30-plus minutes of extra time, it is recommended that team sport athletes ingest carbohydrate during exercise to pre- serve endogenous glycogen and maintain running performance late in exercise.137 Jeukendrup noted that carbohydrates may be oxidized at different rates during exercise due to differenc-


es in absorption rates and the need to convert specific carbohydrates into substrates that can be used by skeletal muscle. Glucose, fructose, galactose, sucrose, and maltose polymers were studied originally with fructose being oxidized at slightly slower rates than glucose and galactose having a 50% slower rate of ox- idation than that of glucose. Consequently, it was recommended that carbohydrates be consumed at a rate no higher than 1 g/min (30 to 60 g/h). Recent research, however, has demonstrated that ingesting multiple transportable carbohydrates that use different intestinal transporters increased carbohydrate delivery and that this carbohydrate can be oxidized at rates in excess of 1 g/min.138 Results were mixed in a 2015 literature review on the effects of ingesting 30 to 60 g carbohydrate per hour


on intermittent sports performance for sprinting, sport-specific skills, and change of speed direction. Car- bohydrate ingestion was minimally effective for jumping and cognitive function; however, carbohydrate ingestion seemed to have the greatest impact on the development of permanent fatigue and hypoglycemia, such as toward the end of a long match.52


Te available research suggests that 30 to 60 g/h of carbohydrate


intake consistently enhances high-intensity intermittent performance with longer time to exhaustion and greater distance covered, and it may be more important to performance when carbohydrate is consumed before/during a high-intensity event vs a lower-intensity session.131,139


Solid (bar) or semisolid (gel or chew)


carbohydrate are oxidized at the same rate as carbohydrate solution as long as sufficient water was con- sumed. Carbohydrate gels can improve endurance capacity in high intensity intermittent exercise.139


Te


exact amount and timing of the carbohydrate intake should be determined according to the individual’s needs and a number of factors specific to the sport. For a detailed discussion and recommended guidelines for determining individual recommendations, refer to the review by Baker and colleagues.52 Carbohydrate recommendations are more precisely expressed on a gram per kilogram basis.127,140,141 Te current recommendations for athletes engaged in HIIE are summarized in Table 21.4.123,141-143


Specific 476 SECTION 4: SPORTS-SPECIFIC NUTRITION GUIDELINES


Another study by Russell and colleagues documented a transient


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