Effect of concurrent resistance and endurance exercise on muscle growth in healthy men.

The study will employ a, parallel-groups design incorporating diet and exercise manipulation. Following appropriate preliminary testing, subjects will be assigned to one of three experimental groups: Resistance Exercise Only and High Protein Diet (Group 1), Endurance Exercise Only and High Protein Diet (Group 2), or Concurrent Resistance and Endurance Exercise and High Protein Diet (Group 3). Skeletal muscle biopsies will be obtained at rest (i.e.: 2 weeks before intervention commencement), 3 days following the first exercise session, after 4 weeks of training, after 8 weeks of training, and three days after the 12-wk training and nutrition intervention. There is no placebo group as the main purpose of this study is to determine whether nutritional strategies such as increased protein ingestion through a ‘high protein diet’ can offset declines in muscle strength and hypertrophy with chronic (i.e.: 12 weeks) concurrent training. Body Composition and Urine Sample: A dual energy X-ray absorptiometry scan (DXA) is a specialised X-ray technique to provide a measure of body composition. This is just like a normal X-ray, with no pain involved and it will measure total body mass, fat mass and lean mass. Participants will be scanned wearing light clothing at the beginning, 4 weeks, 8 weeks and conclusion of the study. Ultrasound Two-dimensional ultrasound is the most common technique used for assessing the structure of a muscle. Two-dimensional ultrasound will then be used to assess the structure of the quadriceps muscles at three sites along the length of the thigh. Participants will then have the structure of their hamstring muscles assessed. Strength and Power Testing Maximum muscular strength will be determined during a series of one repetition maximum (1RM) attempts and during an isometric mid-thigh pull (IMTP). The 1RM attempts will be performed on the leg press, leg extension, and bench press exercises. 1RM values from this test will be used to prescribe individualized training ranges/intensity..The IMTP is a simple test performed on a force platform that assesses lower-body strength. Participants will be shown correct and safe technique for each exercise by a qualified exercise physiologist and will subsequently be provided with appropriate time to safely perform each technique until competent and comfortable. To assess power output, participants will perform two different jumps on the force platform: a countermovement jump (CMJ) and a squat jump (SJ). During the CMJ, participants will place their hands on their hips and try to jump as high as they can. As per the strength testing, participants will receive adequate instruction and demonstration prior to completing the testing. VO2Peak Test The VO2peak test is an incremental test to exhaustion on a stationary cycle ergometer. The workload increases every 2½ minutes until you can no longer maintain a pedalling rate of 60-70 rpm. This test is expected to last between 10-15 minutes. During the test expired air will be sampled as participant breathe into a mouthpiece attached to an automated gas analyser. The results from this test will provide a peak oxygen consumption reading and peak power output (PPO) and physiological data regarding cardiovascular health and fitness. PPO from this test will be used to prescribe individualized training ranges/intensity. Dietary Intervention For the duration of the 12-week exercise and nutrition intervention, participants will consume a ‘high’ protein diet. A diet is considering high in protein if it consumed above the recommended daily intake of 0.8g/kg/day. In this study, daily protein intake will be set at 2 g/kg/day, with a recommended total daily energy intake of 30 – 40 kcal/kg/day. This level of protein consumption is completely safe with similar, and in many cases, higher quantities used within the research field. Individual diet counselling as well as personal food and recipe plans will be provided face-to-face and via phone (based on availability) by the study dietitian on a fortnightly basis throughout the entire study. These appointments will typically range from 30-60 minutes. Participants will log their food intake using the Easy Diet Diary™ mobile phone App or manually through a ‘food diary’. Exercise Training Program All training sessions will be held in the exercise physiology labs/gyms located at ACU under direct supervision of Mr. Shamim and Dr. Camera. Mr. Shamim has extensive experience with intercollegiate strength and conditioning, powerlifting, and holds a Master's of Research degree in Sport and Exercise Sciences. Dr. Camera is a qualified personal training and holds a doctorates in Exercise Science. Sessions will be delivered in a group setting and last approximately 60 minutes each. Group 1: Resistance Exercise Only with High Protein Diet Participants in Group 1 will consume a ‘high protein’ diet as described above and perform only resistance exercise three times per week for the duration of the 12-wk training period. Resistance exercise will progressively increase in weight to account for increases in muscle size and strength throughout the program. The resistance exercise protocol will consist of a whole-body routine including the following types of exercises: chest press, lat pulldown, rows, leg extension, leg press, shoulder press and lunges. 1) Phase 1 – Familiarization (Week 1): Sessions in this period will introduce main movements and exercises (~60-65% 1RM). 2) Phase 2 – Hypertrophy (Weeks 2-6): Sessions in this period will focus primarily on building muscle mass through higher volume of repetitions per session. Load will increase in a linear progression throughout this phase (~65-80% 1RM). 3) Phase 3 – Power (Week 7): Sessions in this phase of training will act as a ‘de-loading’ period and aim to improve muscle power in primary movements (~60-70% 1RM) 4) Phase 4 – Strength (Weeks 8-10): Sessions in this phase will focus on strength development and consist of a lower volume of repetitions paired with heavier weights. A linear increase in load will also be used during this phase (~80-90% `1RM) 5) Phase 5 – Peaking (Weeks 11-12): Sessions in this phase will focus solely on peaking the neuromuscular system and preparing for the main movements performed during the final strength testing. (~90-95% 1RM) Participants in the resistance exercise group will be required to training on three occasions per week (Monday, Wednesday, and Friday OR Tuesday, Thursday, and Saturday). Group 2: Endurance Exercise Only with High Protein Diet Participants in Group 2 will consume a ‘high protein’ diet as described above and perform only endurance-based exercise on a stationary exercise bike three times per week for the duration of the 12-wk training period. Endurance exercise will consist of variety of diverse exercise sessions including: • 30-45 minutes of moderate intensity cycling on a stationary ergometer at approximately 50-75% of VO2peak capacity at a speed of approximately 60-70 rpm • 30-45 minutes of high-intensity interval training involving 5 mins of cycling at approximately 75-85% of each individual’s pre-determined VO2peak capacity with 60 seconds of recovery period. • 30-45 minutes of Sprint interval training involving <60 seconds of cycling at approximately 85-100% of each individual’s pre-determined VO2peak capacity with varying recovery periods of 30 seconds, 40 seconds, 1 minute, or 4 minutes based on session. Participants in the endurance exercise group will be required to training on three occasions per week (Monday, Wednesday, and Friday OR Tuesday, Thursday, and Saturday). Group 3: Combined Resistance and Endurance Exercise with High Protein Diet Participants in Group 3 will consume a ‘high protein’ diet as described above and will perform combined resistance and endurance exercise six times per week for the duration of the 12-week training period. The concurrent training program will incorporate the same resistance and endurance exercise protocols mentioned in Group 1 and Group 2, respectively, on alternate days. Therefore participants in this combined exercise group will be required to perform resistance training on Monday, Wednesday, and Friday, and endurance training on Tuesday, Thursday, and Saturday, each week. Muscle Tissue Biopsy Muscle tissue biopsies will be collected on four occasions (Figure 1) during the study: (1) Before the commencement of the 12-week training program (Week -2) (2) 3 days after the completion of the 2nd week of exercise training (Week 3); (3) 3 days after the completion of the 8th week of exercise training (Week 9); and (3) 3 days after the completion of the 12-wk training program (Week 13). Muscle biopsies are necessary in order to measure muscle growth responses to the respective diet and exercise interventions. The muscle biopsy procedure will be conducted by our study doctor who possesses extensive experience in the technique. The muscle biopsy sample is obtained from the outer thigh as this muscle site contains few surface sensory nerves. In preparation for a biopsy, a small amount of local anesthetic is injected under the skin which may result in a mild burning sensation while the fluid is injected. A small, 4-5 mm incision will then be made into your skin to create an opening for the biopsy needle. There is often a small amount of bleeding from the incision; however this bleeding is generally minimal. The biopsy needle will then be inserted through the incision site. There may also be some minimal bleeding when the needle is removed which may require the application of pressure for a few minutes. At the completion of each biopsy, the incision will be closed with sterile tape and wrapped with a bandage. Participants are advised to refrain from excessive muscle use for the remainder of the day.