Exercise Metabolism
Conditions
Brief summary
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.
Interventions
OTHERModerate-intensity (relative) exercise with glucose ingestion
120 minutes of cycling at 95% of lactate threshold ingesting 90 g/h of glucose
OTHERModerate-intensity (absolute) exercise with glucose ingestion
120 minutes of cycling at a power matched to participant in the \<70 kg body mass group, ingesting 90 g/h of glucose
Sponsors
University of Birmingham
University of Bath
Study design
Observational model
CASE_CONTROL
Time perspective
CROSS_SECTIONAL
Eligibility
Sex/Gender
ALL
Age
18 Years to 60 Years
Healthy volunteers
Yes
Inclusion criteria
* Able to cycle continuously for 2 hours at a moderate intensity * VO2max of between 40-75 mL/kg/min * Fat-mass index (determined by dual energy x-ray absorptiometry) \< 5.5 kg·m-2
Exclusion criteria
* Diagnosed disorders of the gastrointestinal tract (e.g. crohn's, colitis etc.) * People following a low-carbohydrate, high-fat diet * Pregnant or lactating * Diagnosed cardiovascular disease * Possible symptoms of cardiovascular disease * Diagnosis of diabetes of any type * Hypercholesterolaemia (total cholesterol ≥ 6.2 mmol/L * Hypertension (systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg) * Current smoker * Family history of coronary artery disease (first-degree relative \<60 years) * Prevalence of vascular disease * Autonomic neuropathy * Kidney disease * Diagnosed pulmonary disease (e.g. chronic obstructive pulmonary disease, asthma, interstitial lung disease or cystic fibrosis) * Blood borne disease or infection * Osteoporosis * Osteoarthritis * Blood clotting disorders * Food intolerances/allergies (these may not specifically exclude you- please talk to the investigator) * Sensitivity or allergy to anaesthetic
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Peak exogenous carbohydrate oxidation rate (g/min) | 120 minute | Peak exogenous carbohydrate oxidation rate (g/min) |
| Total exogenous carbohydrate oxidation (g) | minutes 30-120 of exercise | Sum of exogenous carbohydrate oxidation in g |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Whole-body carbohydrate oxidation rate (mg/kgFFM) | Sum of minutes 30-120 of exercise | Sum of whole-body carbohydrate oxidation (mg/kgFFM) |
| Endogenous carbohydrate oxidation rate (g) | minutes 30-120 of exercise | Sum of endogenous carbohydrate oxidation (g) |
| Endogenous carbohydrate oxidation rate (mg/kgFFM) | minutes 30-120 of exercise | Sum of endogenous carbohydrate oxidation (mg/kgFFM) |
| Whole-body fat oxidation rate (g) | minutes 30-120 of exercise | Sum of whole-body fat oxidation (g) |
| Whole-body fat oxidation rate (mg/kgFFM) | minutes 30-120 of exercise | Sum of whole-body fat oxidation (mg/kgFFM) |
| Plasma lactate concentrations (mmol/L) | minutes 0-120 of exercise | Plasma lactate concentrations (mmol/L) |
| Plasma glucose concentrations (mmol/L) | minutes 0-120 of exercise | Plasma glucose concentrations (mmol/L) |
| Plasma non-esterified fatty acid concentrations (mmol/L) | minutes 0-120 of exercise | Plasma non-esterified fatty acid concentrations (mmol/L) |
| Plasma insulin concentrations (pmol/L) | minutes 0-120 of exercise | Plasma insulin concentrations (pmol/L) |
| Dietary carbohydrate intake (grams/day) | 72-hour food diary in g/d | Dietary carbohydrate intake (grams/day) |
| Total exogenous carbohydrate oxidation (g/kgFFM) | minutes 30-120 of exercise i | Sum of exogenous carbohydrate oxidation (g/kgFFM) |
| Dietary fibre intake (grams/day) | 72-hour food diary | Dietary fibre intake (grams/day) |
| Dietary fat intake (grams/day) | 72-hour food diary | Dietary fat intake (grams/day) |
| Dietary protein intake (grams/day) | 72-hour food diary | Dietary protein intake (grams/day) |
| Dietary energy intake (kiloJoules/day) | 72-hour food diary | Dietary energy intake (kiloJoules/day) |
| Dietary energy intake (kilojoules/kilogram/day) | 72-hour food diary | Dietary energy intake (kilojoules/kilogram/day) |
| Dietary carbohydrate intake (grams/kilogram/day) | 72-hour food diary | Dietary carbohydrate intake (grams/kilogram/day) |
| Dietary sugar intake (grams/kilogram/day) | 72-hour food diary | Dietary sugar intake (grams/kilogram/day) |
| Dietary fibre intake (grams/kilogram/day) | 72-hour food diary | Dietary fibre intake (grams/kilogram/day) |
| Dietary fat intake (grams/kilogram/day) | 72-hour food diary | Dietary fat intake (grams/kilogram/day) |
| Dietary protein intake (grams/kilogram/day) | 72-hour food diary | Dietary protein intake (grams/kilogram/day) |
| Dietary sugar intake (grams/day) | 72-hour food diary | Dietary sugar intake (grams/day) |
| Whole-body carbohydrate oxidation rate (g) | minutes 30-120 of exercise | Sum of whole-body carbohydrate oxidation (g) |
Countries
United Kingdom
Outcome results
None listed