Author(s): HOMER, K., JUKIC, I., CROSS, M., HELMS E., Institution: AUCKLAND UNIVERSITY OF TECHNOLOGY, Country: AUSTRALIA, Abstract-ID: 1029

INTRODUCTION:
To acutely enhance appearance and thus performance, bodybuilders implement carbohydrate (CHO) loading protocols in the week before the competition (known as peak week [PW]) to increase muscle size through the supercompensation of muscle glycogen. While the use of such strategy is seemingly prevalent, experimental designs in the context of bodybuilders are lacking, whereby the only existing trial is limited. Thus, the aim of this study was to assess the effect of an ecologically valid bodybuilding CHO-loading protocol on anthropometric measures.
METHODS:
Four dieting, resistance-trained males who met the inclusion criteria of ∑8 skinfolds (SF) ≤48mm (range: 34.5-45mm) participated in this randomised crossover design. This criterion was used to replicate the very low body fat levels of male bodybuilders during PW. Participants were also dieting for ≥8 weeks to represent the physiological conditions of bodybuilders during competition preparation. Each experimental period, separated by a 9-day wash-out, consisted of data collection on days 1, 4, and 5 which correspond to baseline, post-depletion, and post-loading phases of the protocol, respectively. During depletion, participants followed a standardised training regime and diet (2.2-2.6g/kg protein, 1-2g/kg CHO, 0.5g/kg fat relative to body mass [BM]) representative of the practices of bodybuilders during PW. This diet was maintained on day 4 with the addition of placebo (PLA) or CHO shakes which contained 9g/kg CHO for the post-loading data collection on day 5. Outcomes comprised of BM, SF, and ∑5 ultrasound muscle thickness (MT) which were obtained at each data collection in the morning at the same time (±1hr) after an overnight fast. Descriptive data at the group level from each day was used to assess changes.
RESULTS:
From baseline, BM (CHO: 76 to 75.5kg; PLA: 75.4 to 75.1kg), SF (CHO: 38.9 to 37.6cm; PLA: 38.8 to 38.8mm), and MT (CHO: 23.9 to 23.7mm; PLA: 24.3 to 24.1mm) mostly decreased following depletion in both conditions. After loading, all outcomes increased in the CHO condition (BM: 76.1kg, SF: 38mm, MT: 24.4cm) but not in PLA (BM: 74.7kg, SF: 38.6mm MT: 24.1cm) from post-depletion. However, these changes were not as pronounced in comparison to the baseline in both conditions.
CONCLUSION:
The implementation of a bodybuilding CHO-loading protocol may not meaningfully change BM, SF, and MT following the ingestion of 10-11g/kg of CHO in a day. While small group level changes seemingly favour CHO-loading, it is difficult to interpret these differences as large enough to exceed potential measurement error and daily biological fluctuations, and thus may not represent a meaningful change. Based on the preliminary findings, it can be interpreted that it may not be worthwhile for competitors to implement such a drastic protocol. However, outcomes such as change in visual appearance need to be quantified to fully elucidate the effects of the protocol on bodybuilding performance.