Carbohydrate consumption and variable-intensity exercise responses in boys and men
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The effect of carbohydrate (CHO) supplementation on physiological and perceptual responses to steady-state exercise has been studied in children. However, little is known about these responses to variable-intensity exercise (VIE) and how these responses might differ from adults. This study examined the physiological and perceptual effects of CHO on VIE in boys and men.
Eight boys (11.1 ± 0.9 years) and 11 men (23.8 ± 2.1 years) consumed CHO or a placebo (PL) beverage before and throughout VIE (three 12-min cycling bouts with intensity varying every 20–30 s between 25, 50, 75, and 125% peak work rate). Pulmonary gas exchange was assessed during the second 12-min bout. RPE was assessed twice per bout.
In CHO, blood glucose increased and then decreased more from pre-exercise to 12 min and was higher in this trial at the end of exercise in men versus boys. In boys, blood glucose in CHO was higher at 24 and 36 min of exercise than in PL. RER during the CHO trial was higher in both groups; the other physiological responses were unaffected by CHO. All RPE measures (whole body, legs and chest) increased over time, but were not different between groups or trials.
Blood glucose patterns during VIE were differentially affected by CHO in boys and men, but most physiological and perceptual responses to VIE were unaffected by CHO in either group. Knowledge of the underlying mechanisms of glucose regulation and effects on physical performance during this type of exercise in children is warranted.
KeywordsBlood glucose Metabolism Child–adult difference Cycle ergometry
Analysis of variance
Loughborough Intermittent Shuttle Test
Respiratory exchange ratio
Rating of perceived exertion
LMG and ADM developed the study, participated in the data collection and analysis, and are the paper’s primary authors. MPR and JPG assisted with some of the data collection and reviewed drafts of the paper prior to submission.
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Compliance with ethical standards
Conflict of interest
None of the authors declare competing financial interests.
- Bar-Or O, Ward DS (1989) Rating of perceived exertion in children. In: Bar-Or O (ed) Advances in pediatric sports sciences, vol 3. Human Kinetics Publishers, Champaign, pp 151–168Google Scholar
- Eriksson BO (1972) Physical training, oxygen supply and muscle metabolism in 11-13-year old boys. Acta Physiol Scand Suppl 384:1–48Google Scholar
- Eriksson O, Saltin B (1974) Muscle metabolism during exercise in boys aged 11 to 16 years compared to adults. Acta Paediatr Belgica Suppl 28:257–265Google Scholar
- Eriksson BO, Gollnick PD, Saltin B (1973) Muscle metabolism and enzyme activities after training in boys 11–13 years old. Acta Physiol Scand 87(4):485–497. https://doi.org/10.1111/j.1748-1716.1973.tb05415.x CrossRefGoogle Scholar
- Mahon AD, Guth LM, Kraft KA (2010) Physiological and perceptual responses in children during variable-intensity exercise. In: Baquet G, Berthoin S (eds) Children and exercise XXV. Routledge, London, pp 171–177Google Scholar
- Noble BJ, Robertson RJ (1996) Perceived exertion. Human Kinetics, ChampaignGoogle Scholar
- Phillips SM, Turner AP, Gray S, Sanderson MF, Sproule J (2010) Ingesting a 6% carbohydrate-electrolyte solution improves endurance capacity, but not sprint performance, during intermittent, high-intensity shuttle running in adolescent team games players aged 12–14 years. Eur J Appl Physiol 109(5):811–821. https://doi.org/10.1007/s00421-010-1404-z CrossRefGoogle Scholar
- Phillips SM, Turner AP, Sanderson MF, Sproule J (2012) Carbohydrate gel ingestion significantly improves the intermittent endurance capacity, but not sprint performance, of adolescent team games players during a simulated team games protocol. Eur J Appl Physiol 112(3):1133–1141. https://doi.org/10.1007/s00421-011-2067-0 CrossRefGoogle Scholar
- Stevens J (2002) Applied multivariate statistics for the social sciences. Lawrence Erlbaum Associates, MahwahGoogle Scholar
- Tanner JM (1962) Growth at adolescence, with a general consideration of the effects of hereditary and environmental factors upon growth and maturation from birth to maturity, 2d edn. Blackwell Scientific Publications, OxfordGoogle Scholar