Carbohydrate Concentration Influences Intermittent Endurance Capacity During Prolonged Intermittent High-Intensity Shuttle Running in Adolescents

Abstract

Recent work from this laboratory demonstrated, for the first time, a significant improvement in intermittent endurance running capacity (time to exhaustion) during prolonged intermittent, high-intensity shuttle running when 12-14 year old team games players ingested a 6% carbohydrate-electrolyte (CHO-E) solution immediately before and during exercise. Research into the optimal carbohydrate (CHO) concentration for young team games players requires further study. PURPOSE: To investigate the influence of consuming a 2, 6, and 10% CHO-E solution immediately prior to, and during, a simulated team games protocol on the intermittent, high-intensity endurance running capacity and sprint performance of 12-14 year old team games players. METHODS: Seven participants (five males and two females; mean age 13.3 ± 0.5 years, height 1.71 ± 0.05 m, body mass (BM) 62.0 ± 6.3 kg) performed three trials separated by 3-7 days. In each trial, they completed 60 min of exercise composed of four 15 min periods of part A of the Loughborough Intermittent Shuttle Test, followed by an intermittent run to exhaustion (part B). Participants consumed the CHO-E solutions in a double-blind, randomised, counterbalanced fashion during the 5 min pre-trial (5 ml.kg-1 BM) and after each 15 min period of part A (2 ml.kg-1 BM). RESULTS: Ingesting the 6% CHO-E solution enabled a 34.1% increase in intermittent endurance capacity compared with the 10% solution (5.5 ± 0.8 vs. 4.1 ± 1.5 min, P < 0.05) and a 14.6% increase compared with the 2% solution, although this was not significant (P = 0.10). There was no significant difference in intermittent endurance capacity between the 2% and 10% solutions (P = 0.09). Distance covered during part B was significantly greater with the 6% solution compared with the 10% solution (931 ± 172 vs. 706 ± 272 m, P < 0.05). There was no significant between-trials difference for mean 15 m sprint time or peak sprint time (P = 0.37), or heart rate (P = 0.23). CONCLUSION: Ingesting a 6% CHO-E solution significantly improves the intermittent, high-intensity endurance running capacity of adolescent team games players compared with a 10% solution. The 14.6% improvement in endurance capacity with the 6% compared with the 2% solution, while not significant, suggests that a 6% CHO-E solution should be the solution of choice for young team games players.