Although changes in body composition and their physiological associations during periods of competition preparation in bodybuilders have been scientifically documented, this has been through single case studies, i.e., single subjects and cohorts. Therefore, there is a paucity of comprehensive longitudinal data in natural bodybuilders.

Given the increasing popularity of competitive bodybuilding, there is a need for research into nutritional practices, training and physiological implications to ensure the success of bodybuilders.

A prospective study has just been published that aimed to describe the body composition and physiological changes experienced by 9 male and natural bodybuilders (initially 11 but 2 dropped out) in the 16-week period prior to competition and up to 4 weeks after competition.

Based on previously documented physiological changes associated with long-term energy restriction and high energy expenditure, it is hypothesized that the bodybuilders would experience large reductions in body fat percentage, with concomitant reductions in muscle tissue and resting energy expenditure (RMR) as well as a drop in serum testosterone, IGF-1 and increased cortisol levels.

Of the nine participants, eight competed in a national competitive event in their respective categories, with three of them ranked in the top 10, two ranked third, two ranked second, and one ranked first, who also participated in an international competition. These findings are valuable, given the paucity of research on natural bodybuilders.

What was most striking about the results of the study?

Well, contrary to what was thought, the participants did not have a substantial decrease in muscle tissue or resting metabolic rate (RMR), even though there was a drop in anabolic hormones (total and free testosterone dropped by 38% and 49%, respectively, while IGF-1 dropped by 26%) and an increase in cortisol, which were reversed as soon as there was a change in diet after the competition.

Several participants fell below the reference ranges for serum and free testosterone and IGF-1 during pre-competition. All participants reduced fat percentage to low levels, in some cases to the lower limits for humans. But despite these changes in body composition, muscle mass and RMR remained unchanged throughout the competition and preparation period, while serum testosterone and IGF-1 concentrations were significantly reduced.

The loss of muscle mass documented in this study was relatively small compared to previously reported data. In case reports, natural bodybuilders have been shown to lose up to 10.4 kg of muscle mass during competition preparation (Kistler et al.,2014; Robinson et al., 2015; Rossow et al., 2013).

Some of the reasons why this preparation was successful and there was no drop in muscle mass or RMR were:
Four participants reported that they implemented a refeed during the pre-competition phase, which provides more reasons to assert the success of this strategy.
The study period, while not short, was also not as long as other case studies.
Did not drastically reduce calories
They significantly increased protein intake
They had an equitable distribution of daily protein, which is assumed to maximize protein utilization to optimize protein synthesis.
Did not drastically decrease their carbohydrate intake.
Increased the intensity of training in terms of %RM
I want to make special mention of carbohydrates, as this is often a common misconception. In another study prior to this one, ranked natural bodybuilders consumed during the volume stage an average of between 1.0-1.4 gr/kg bodyweight more carbohydrate than those who did not rank. This equates to an additional 75-97.5 g of additional carbohydrate per day for a 75 kg male. In addition, the classified bodybuilders not only consumed more carbs in the bulking phase, but they did not reduce them as much during the definition phase as the NON-classified bodybuilders.

The maintenance of RMR in the current study, is further evidence that no such perennial adaptations or drastic decreases in metabolism occur as is often thought, but rather usually corresponds to a decrease in NEAT among other factors. Furthermore, because there were hardly any reductions in muscle mass and because the strength training was based on high intensity, which increases basal metabolism up to 24 hours later even in deficit, this helped to maintain RMR. They also documented an exercise session prior to this measurement, which may elevate RMR.

The drop in anabolic hormones such as testosterone and IGF-1 is consistent with published physiology and is due to energy restriction (Dolan et al., 2012). Despite reductions in anabolic hormone concentrations, the bodybuilders in this study were still able to prevent large losses in muscle mass, indicating that the potential loss of muscle tissue that occurs during periods of energy deficit is not associated with changes in testosterone or IGF-1 concentrations.

It also suggests that the high protein intake and strength training program employed by the participants was sufficient to counteract the anti-anabolic effect of these hormonal changes.

The rapid return to baseline testosterone values and IGF-1 concentrations after competition is also significant. This reflects the cessation of the energy deficit. A case study examined hormonal changes after a bodybuilding competition, and found an increase in testosterone by 94% of basal concentrations after 3 months of increased energy intake (Rossow et al., 2013).

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