Speed of Glucose Absorption

The aim of this study is to investigate and compare the speed of delivery of three commercially available carbohydrate supplements during a 1 hour modified glucose tolerance test. This study will be a randomised double-blind crossover in design. Participants will be required to attend the Human Performance Laboratory at Lancaster University on three separate visits. During each visit, participants will be required to consume one of three commercially available carbohydrate supplements, namely Maurten Gel 160 (MAU), Voom Pocket Rocket Electro Energy Bar (PR), and SIS Go Isotonic Energy Gel (SIS). Each consumable will be blinded to both the researchers and participants, flavoured the same (lemon and lime) and placed into identical packaging with anonymised labelling to minimise the risk of bias. The supplements will be matched for carbohydrate content (45 grams). Blinding of supplements will be completed offsite by people not in the research team and followed strict food and hygiene protocols. Each participant will complete all three conditions, consuming one of each supplement at random per condition.

Each visit will involve frequent venous blood sampling for glucose, lactate and insulin. An anterograde venous cannula will be inserted into a vein in the antecubital fossa of the arm by a qualified member of the research team. This is a less invasive alternative to an arterial cannula whilst still allowing for accurate metabolic measures to be taken. This method is also less painful than inserting a retrograde cannula which can cause significant discomfort.

Once the anterograde venous cannula is inserted and secured in place, a resting measurement of blood will be taken (1ml of blood taken to measure glucose and lactate, and 3ml for insulin). Participants will then be required to consume one of the three carbohydrate energy supplements. Once the supplement had been consumed, continuous gas analysis will begin to analyse gas exchange to non-invasively measure substrate utilisation. This signals the start of the test, and a timer will be set for 1 hour.

Throughout the test, blood sampling will be taken in frequent intervals. 1ml of blood sampled every 5 minutes to check for glucose and lactate, and 3ml of blood sampled every 10 minutes for insulin. Gas exchange will be continuously measured to non-invasively measure substrate utilization in the muscle via indirect calorimetry which determines energy expenditure by measuring the body's oxygen consumption and carbon dioxide production. The measurement is based on the assumption that the volume of oxygen (VO2) consumed is used to oxidise fuels, and the volume of carbon dioxide (VCO2) produced is a by-product of substrate utilisation.

After the study visit, analysis will be conducted assessing how each of the three supplements effect blood glucose, blood lactate, insulin, and gas exchange.

Inclusion criteria

• Aged between 18-35 years
• Males
• Tier 2 runners, cyclists, and triathletes; local level representation, training ~ 3 times per week, training with a purpose to compete, identify with a specific sport, limited skill development
• BMI between 18.5-24.9 - based on healthy weight range for BMI as per NHS and BMI of recreational to elite long-distance runners

Exclusion criteria

• Allergies to any listed ingredients on any supplements.
• Diabetes (type 1 or 2)
• Any medical conditions
• Smokers
• Anyone using drugs or medication
• Anyone consuming alcohol within 24 hours of the study
• Exercise must be restricted within 24 hours of the study
• Caffeine must not be consumed within 24 hours of testing as it can significantly enhance carbohydrate oxidation rates
• Diets including high-carbohydrate-low-fat (HCLF), low-carbohydrate-high-fat (LCHF), ketogenic, and/or glycogen manipulation diets