Circulatory Levels of Irisin in Response to Chronic Resistance Training

Objective: The purpose of this study is to study the circulating levels of irisin in response to chronic high-intensity resistance training in a group of healthy young adults. Sample: The sample will be comprised 44 of adult men and women unpaid volunteers between the ages of 18 and 30. Pre-screening assessments: Informed consent, PAR-Q, Medical History and Exercise History will be used to determine health status and prior exercise experience. Menstrual cycle log will be required for female participants. Pre-Intervention assessments: * Anthropometric measurements and Body Composition: Height, triceps, thigh and calf skinfolds, biceps, thigh, hip, waist, and calf circumferences will be measured. Dual-energy x-ray absorptiometry (DEXA) will be performed to obtain body composition. * Cardiopulmonary and Strength Fitness Testing. Cardiopulmonary fitness will be determined via maximum oxygen uptake testing. One maximum repetition (1-RM) will be used to assess the muscular fitness. * Spontaneous Physical Activity: Daily activity level for 7 days will be collected. * Familiarization. Participant will be instructed on the muscle conditioning techniques used for strength training so that the techniques can be mastered. The rate of perceived exertion (RPE) scale will also be used for familiarization during these sessions. Intervention: The intervention will last 3 weeks with a frequency of 3 training session per week. We will collect blood samples levels at session 1 (at the beginning of week 1), session 3 (at the end of week 1), at session 6 (at the end of week 2) and session 9 (at the end of week 3). Blood draws will occur at the beginning of each session evaluated (pre-session), at the 45 min mark during each session and immediately after each session (post-session). The sessions will consist on a circuit training of 3 sets of 7 exercises focused on major muscle groups. Ten repetitions on each circuit at 70% of the maximum capacity will be performed. During the intervention: \- Blood-related variables. Baseline glucose, lactate and hematocrit will be obtained from all participants prior to intervention. Lactate and Hematocrit will be obtained pre-intervention and post-intervention, and within 1 min post workout at sessions 1, 3, 6 and 9. Irisin will be obtained from blood samples at baseline, during and after training sessions 1, 3, 6 and 9. Irisin will be measured via a commercial enzyme-linked immunosorbent assay. \- Dietary Controls. Each participant will complete the Food Preference Questionnaire. In addition, the Automated Self-Administered 24-hour Recall (ASA24) will be collected for the days prior to sessions 1, 3, 6 and 9. Post-Intervention assessments: * Anthropometric measurements and Body Composition: Height, triceps, thigh and calf skinfolds, biceps, thigh, hip, waist, and calf circumferences will be measured. Dual-energy x-ray absorptiometry (DEXA) will be performed to obtain body composition. * Caridorespiratory capacity determined via maximum oxygen uptake testing. One maximum repetition (1-RM) will be used to assess the muscular fitness. * Spontaneous Physical Activity: Daily activity level for 7 days will be collected.