Upper-body High-intensity Interval Training and Mixed Meal Responses

The aim of this research is to determine the metabolic responses to a mixed-meal tolerance test following an acute bout of HIIE and an energy-matched MICE bout in able-bodied persons. The hypothesis is that HIIE and MICE will be more effective at reducing the total triglyceride responses compared to a resting control condition. Preliminary measurements: Preliminary testing will include measurements of weight and height. There will also be an assessment of resting metabolic rate and maximal exercise capacity. On a second visit, a HIIE familiarisation session will be performed to determine total energy expenditure of the session. All of the exercise protocols will take place on an arm crank ergometer at the University of Bath. Main trial days: Before all main trials, participants will be asked to refrain from performing any strenuous physical activity in the 48-h prior (i.e. day 0 and 1) and consuming alcohol/caffeine in the 24-h prior (i.e. day 1). On day 1, participants will be asked to record/replicate their diet using a weighed food-diary. Participants will be asked perform exercise (HIIE and MICE only) at 18:00 on day 1, having consumed no food (other than plain water) from 14:00. They will be given a standardised dinner to eat at 20:00, and asked to avoid the ingestion of any further food (other than plain water) for the rest of the evening. On day 2 and upon arrival to the laboratory, a cannula will be inserted into a vein, and a baseline blood sample and expired air sample will be taken. The participant will then be asked to consume a smoothie, consisting of peanut butter, banana, coconut oil, sugar, and chocolate-flavoured whey protein powder. The meal should be consumed within 10 minutes and blood samples will be taken from the cannula at 15, 30, 45 60, and 90 minutes and then at every hour for 5 hours after consumption of the meal to monitor changes in metabolic markers. Expired gas samples will also be taken hourly and indirect calorimetry will be used to estimate relative fat and carbohydrate metabolism in response to the meal.