CHO Oxidation from a CHO Gel Compared with a Drink during Exercise

• Published in: Medicine and science in sports and exercise 2010-11, Vol.42 (11), p.2038-2045
• Main Authors: PFEIFFER, Beate, STELLINGWERFF, Trent, ZALTAS, Eric, JEUKENDRUP, Asker E
• Format: Article
• Language: English
• Subjects: Adult; Beverages; Biological and medical sciences; Carbohydrate Dehydrogenases - metabolism; Dietary Carbohydrates - administration & dosage; Dietary Carbohydrates - adverse effects; Dietary Carbohydrates - metabolism; Exercise; Exercise Test; Fundamental and applied biological sciences. Psychology; Gastrointestinal Tract - drug effects; Gels - administration & dosage; Humans; Male; Space life sciences; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports
• ISSN: 0195-9131; 1530-0315
• DOI: 10.1249/MSS.0b013e3181e0efe6

Recently, it has been shown that ingestion of solutions with glucose (GLU) and fructose (FRC) leads to 20%–50% higher CHO oxidation rates compared with GLU alone. Although most laboratory studies used solutions to deliver CHO, in practice, athletes often ingest CHO in the form of gels (semisolid). It is currently not known if CHO ingested in the form of a gel is oxidized as effectively as a drink. To investigate exogenous CHO oxidation from CHO provided in semisolid (GEL) or solution (DRINK) form during cycling. Eight well-trained cyclists(age = 34 ± 7 yr, mass = 76 ± 9 kg, VO2max = 61 ± 7 mL·kg−¹·min−¹) performed three exercise trials in random order. The trials consisted of cycling at 59% ± 4% VO2max for 180 min while receiving one of the following three treatments: GEL plus plain water, DRINK, or plain water. Both CHO treatments delivered GLU plus FRC in a ratio of 2:1 at a rate of 1.8 g·min−¹ (108 g·h−¹). Fluid intake was matched between treatments at 867 mL·h−¹. Exogenous CHO oxidation from GEL and DRINK showed a similar time course,with peak exogenous CHO oxidation rates being reached at the end of the 180-min exercise. Peak exogenous CHO oxidation rates were not significantly different (P = 0.40) between GEL and DRINK (1.44 ± 0.29 vs 1.42 ± 0.23 g·min−¹, respectively). Furthermore, oxidation efficiency was not significantly different (P = 0.36) between GEL and DRINK (71% ± 15% vs 69% ± 13%, respectively). This study demonstrates that a GLU + FRC mixture is oxidized to the same degree then administered as either semisolid GEL or liquid DRINK, leading to similarly high peak oxidation rates and oxidation efficiencies.