Whilst theoretically, body size should influence the capacity for intestinal carbohydrate absorption and thus exogenous oxidation rates during exercise, there is currently little empirical evidence to support this hypothesis. Accordingly, current nutrition guidelines for carbohydrate intake during exercise do not take body mass into account. Therefore, there is a need to establish whether body mass is related to exogenous carbohydrate oxidation rates during exercise. If such a relationship is established, this would lay the foundation to revise the current sports nutrition guidelines regarding carbohydrate intake during exercise. The aims of this study are, therefore, to: 1) establish whether larger individuals display higher rates of exogenous carbohydrate oxidation than smaller individuals; and 2) establish if such a difference can be explained by the higher absolute exercise intensity, and thus the energy demand of exercise. It is hypothesised that larger individuals will demonstrate higher exogenous carbohydrate oxidation rates than smaller individuals, and that this difference will be partly (but not completely) diminished when the absolute intensity of exercise is matched.
Study Type
OBSERVATIONAL
Enrollment
20
120 minutes of cycling at 95% of lactate threshold ingesting 90 g/h of glucose
120 minutes of cycling at a power matched to participant in the \<70 kg body mass group, ingesting 90 g/h of glucose
Department for Health, University of Bath
Bath, United Kingdom
Peak exogenous carbohydrate oxidation rate (g/min)
Peak exogenous carbohydrate oxidation rate (g/min)
Time frame: 120 minute
Total exogenous carbohydrate oxidation (g)
Sum of exogenous carbohydrate oxidation in g
Time frame: minutes 30-120 of exercise
Total exogenous carbohydrate oxidation (g/kgFFM)
Sum of exogenous carbohydrate oxidation (g/kgFFM)
Time frame: minutes 30-120 of exercise i
Whole-body carbohydrate oxidation rate (g)
Sum of whole-body carbohydrate oxidation (g)
Time frame: minutes 30-120 of exercise
Whole-body carbohydrate oxidation rate (mg/kgFFM)
Sum of whole-body carbohydrate oxidation (mg/kgFFM)
Time frame: Sum of minutes 30-120 of exercise
Endogenous carbohydrate oxidation rate (g)
Sum of endogenous carbohydrate oxidation (g)
Time frame: minutes 30-120 of exercise
Endogenous carbohydrate oxidation rate (mg/kgFFM)
Sum of endogenous carbohydrate oxidation (mg/kgFFM)
Time frame: minutes 30-120 of exercise
Whole-body fat oxidation rate (g)
Sum of whole-body fat oxidation (g)
Time frame: minutes 30-120 of exercise
Whole-body fat oxidation rate (mg/kgFFM)
Sum of whole-body fat oxidation (mg/kgFFM)
Time frame: minutes 30-120 of exercise
Plasma lactate concentrations (mmol/L)
Plasma lactate concentrations (mmol/L)
Time frame: minutes 0-120 of exercise
Plasma glucose concentrations (mmol/L)
Plasma glucose concentrations (mmol/L)
Time frame: minutes 0-120 of exercise
Plasma non-esterified fatty acid concentrations (mmol/L)
Plasma non-esterified fatty acid concentrations (mmol/L)
Time frame: minutes 0-120 of exercise
Plasma insulin concentrations (pmol/L)
Plasma insulin concentrations (pmol/L)
Time frame: minutes 0-120 of exercise
Dietary carbohydrate intake (grams/day)
Dietary carbohydrate intake (grams/day)
Time frame: 72-hour food diary in g/d
Dietary sugar intake (grams/day)
Dietary sugar intake (grams/day)
Time frame: 72-hour food diary
Dietary fibre intake (grams/day)
Dietary fibre intake (grams/day)
Time frame: 72-hour food diary
Dietary fat intake (grams/day)
Dietary fat intake (grams/day)
Time frame: 72-hour food diary
Dietary protein intake (grams/day)
Dietary protein intake (grams/day)
Time frame: 72-hour food diary
Dietary energy intake (kiloJoules/day)
Dietary energy intake (kiloJoules/day)
Time frame: 72-hour food diary
Dietary energy intake (kilojoules/kilogram/day)
Dietary energy intake (kilojoules/kilogram/day)
Time frame: 72-hour food diary
Dietary carbohydrate intake (grams/kilogram/day)
Dietary carbohydrate intake (grams/kilogram/day)
Time frame: 72-hour food diary
Dietary sugar intake (grams/kilogram/day)
Dietary sugar intake (grams/kilogram/day)
Time frame: 72-hour food diary
Dietary fibre intake (grams/kilogram/day)
Dietary fibre intake (grams/kilogram/day)
Time frame: 72-hour food diary
Dietary fat intake (grams/kilogram/day)
Dietary fat intake (grams/kilogram/day)
Time frame: 72-hour food diary
Dietary protein intake (grams/kilogram/day)
Dietary protein intake (grams/kilogram/day)
Time frame: 72-hour food diary
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