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Physiological implications of preparing for a natural male bodybuilding competition
Mitchell, Lachlan Slater, Gary Hackett, Daniel Johnson, Nathan O’Connor, Helen
Mitchell, Lachlan
Slater, Gary
Hackett, Daniel
Johnson, Nathan
O’Connor, Helen
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.
Keywords
lean mass, fat mass, resting metabolic rate, protein, hormones, body composition
Date
2018
Type
Journal article
Journal
Book
Volume
18
Issue
5
Page Range
619-629
Article Number
ACU Department
School of Behavioural and Health Sciences
Faculty of Health Sciences
Faculty of Health Sciences
Relation URI
Source URL
Event URL
Open Access Status
License
All rights reserved
File Access
Controlled