Physiological implications of preparing for a natural male bodybuilding competition |
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Authors: | Lachlan Mitchell Gary Slater Daniel Hackett Nathan Johnson Helen O’connor |
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Institution: | 1. Discipline of Exercise and Sport Science, University of Sydney, Lidcombe, Australia;2. Discipline of Nutrition and Dietetics, University of Sunshine Coast, Sippy Downs, Australia |
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Abstract: | This study aimed to describe the body composition and physiological changes which take place during the in-season and recovery periods of a group of natural bodybuilders. Natural male bodybuilders (n?=?9) were assessed 16 (PRE16), 8 (PRE8), and 1 (PRE1) week(s) before, and 4 (POST4) weeks after a bodybuilding competition. Assessments included body composition, resting metabolic rate (RMR), serum hormones, and 7-day weighed food and training diaries. Change in parameters was assessed using repeated-measures analysis of variance. Dietary protein intake remained high throughout the study period (2.8–3.1?g?kg?1?d?1). Fat mass (FM) was significantly reduced from PRE16 to PRE1 (8.8?±?3.1 vs. 5.3?±?2.4?kg, P?.01). There was a small decrease in lean mass (LM) from PRE8 to PRE1 (71.8?±?9.1 vs. 70.9?±?9.1?kg, P?.05). No changes in RMR were observed (P?>?.05). Large reductions in total and free testosterone (16.4?±?4.4 vs. 10.1?±?3.6?nmol?L?1, P?.05; 229.3?±?72.4 vs. 116.8?±?76.9?pmol?L?1, P?.05), and insulin-like growth factor-1 (IGF-1) (27.0?±?7.7 vs. 19.9?±?7.6?nmol?L?1, P?.05) occurred between PRE16 and PRE1. LM and IGF-1 increased from PRE1 to POST4 (70.9?±?9.1 vs. 72.5?±?8.5?kg, P?.05; 19.9?±?7.6 vs. 25.4?±?9.3?nmol?L?1, P?.05). Despite substantial reductions in FM, participants maintained almost all of their LM. The reduction in anabolic hormone concentration is likely attributable to the prolonged negative energy balance, despite a high dietary protein intake. |
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Keywords: | Lean mass fat mass resting metabolic rate protein hormones body composition |
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