Changes in Hormones: Does consuming protein or exercising influence the hormones of healthy adults?

Repeated measures three way randomized cross-over design with three conditions and 24 participants. The three conditions are: exercise only, protein only, and exercise with protein. Participants will be randomly assigned to complete the three interventions in one of six possible orders. Interventions will be conducted at the same time of day, separated by a minimum of one week. Materials: Anthropometric measurement tools (scale, tape measure, bio-electrical impedance device for body composition), cycle ergometer (for VO2 max test and exercise condition), metabolic cart (for VO2 max gas exchange), protein smoothie (for high protein intervention), Low protein high carbohydrate smoothie (for isocaloric placebo), standardized full meal for after all interventions (pizza or allergen free equivalent). Supplement Details: High Protein (30g) Supplement Composition: 30g whey isolate protein powder mixed with 30g of carbohydrate in the form of 8 oz almond milk (2g CHO), 1 banana (23g CHO), 8g chocolate syrup (5g CHO) all blended together to form a chocolate banana smoothie with approximately 1004 kJoules of energy. Low Protein (0g) Supplement Composition: 60g of carbohydrates in the form of 8 oz almond milk (2g CHO), 1 banana (23g CHO), 53g chocolate syrup (35g CHO) all blended together to form a chocolate banana smoothie with approximately 1004 kJoules of energy. Procedures: Initial Testing Session After providing written informed consent, and at least one week prior to participating in the first intervention session, anthropometric measurements and bio-electrical impedance analysis for body composition will be conducted. A maximal oxygen capacity (VO2max) test will then be conducted on a cycle ergometer to determine training status of the participants. This will take approximately 12-15 min, in which intensity is increased in a graded fashion while respiratory gas analysis is conducted. The test will be administered by a trained exercise physiologist (Colleen Gulick). Participants will also fill out a Physical Activity Readiness Questionnaire (PAR-Q) to assess suitability to perform maximal exercise and reduce risk. An exercise history questionnaire will also be completed to determine the amount of exercise they have been performing in the previous three months. Protein Trial Participants will report to the testing facility at 6:30 am after a 10-hour overnight fast. The researcher will confirm that the participant did not exercise for the past 24 hours. After these confirmations the participant will remain seated until 6:45 am, at which point the baseline blood samples will be drawn. The participant will remain seated until 7:30am. Between 7:30 and 7:35am the participant will consume a single dose of a high protein meal. The protein meal will be comprised of 30 g of protein and 30 g of carbohydrate (whey isolate protein powder mixed with fruit smoothie base for taste) totaling 1004 kJoules. A post-intervention blood draw will occur at 7:35 am. From 7:35 am to 10 am the participant will remain seated at the testing site and blood measurements will be conducted every 30 minutes. After 2.5 hours the blood draws will be reduced to one 5mL draw per hour. Participants will be asked to refrain from performing any exercise or eating until the final blood draw of the day (14:00). At 14:05 the participants will be provided with a standardized meal consisting of frozen pizza (or allergen-free equivalent). The following morning the participant will report back to the testing facility and provide a blood sample (via venipuncture) at 7:00 am to see when/if the IGF-1 and IGFBP3 concentrations return to normal after the trial. Exercise Trial The protocol will be the same as described in “Protein Intervention” however, no protein will be consumed between 7:30 am and 7:35 am. Instead, at 7:05 am the participant will perform a 20-minute exercise protocol based on the results of their initial testing session. The exercise will consist of four cycles of: 4 minutes at 15% of aerobic threshold power followed by 30 seconds of maximum effort. The session will end with 2 minutes at 15% aerobic threshold power. Participants will be given an iso-caloric placebo meal consisting of 0 g protein and 60 g of carbohydrate (fruit smoothie) at 7:30 am. In this way the caloric intake will be controlled between all trials and any affects will be a result of protein ingestion. Exercise and Protein Trial The protocol will be the same as described in “Protein Intervention” however, exercise will be conducted between 7:05 am and 7:30 am before consumption of the single high protein (30 g) supplement between 7:30 am and 7:35 am. Supplement Details: High Protein (30g) Supplement Composition: 30g whey isolate protein powder mixed with 30g of carbohydrate in the form of 8 oz almond milk (2g CHO), 1 banana (23g CHO), 8g chocolate syrup (5g CHO) all blended together to form a chocolate banana smoothie with approximately 1004 kJoules of energy. Who: Exercise physiologist (to deliver intervention) & research nurse (perform cannulation) Mode of Delivery: face to face delivery. Interventions may be conducted as a group if scheduling permits but each participant will adhere to their own individualized and randomized intervention. Number of Times: 3 sessions (once per week) Duration: 7 hours each session Location: University of Otago, Dunedin, New Zealand