The effect of a bodybuilding carbohydrate-loading protocol on anthropometry: preliminary findings from a randomized crossover trial

To acutely enhance muscle size and definition, carbohydrate (CHO)-loading protocols are commonly implemented by bodybuilders in the week before competition. This study sought to evaluate the effects of a bodybuilding CHO-loading protocol on anthropometry. Four dieting males engaging in resistance training (RT) with very low body fat participated in this randomized crossover trial. Each experimental period consisted of data collection on days one, four, and five corresponding to baseline, postdepletion, and postloading phases, respectively. During depletion, a standardized RT regimen and diet was followed. This diet was maintained on day 4 with the addition of placebo (PLA) or CHO drinks which contained 9 g/kg BM CHO for postloading data collection on day 5. Body mass (BM), skinfold thickness (SF), and ultrasound muscle thickness (MT) were obtained with descriptive data at both group and individual level calculated. From baseline, BM, SF, and MT mostly decreased in both conditions following depletion. All outcomes then increased from postdepletion following CHO-loading (BM: +0.8%, SF: +1.1%, MT: +2.9%) but not with PLA. Comparing to baseline, postloading changes were greater with CHO (BM: +0.3%, SF: -2.3%, MT: +2.1%) than PLA (BM: -0.9%, SF: -0.5%, MT: -0.8%). Individual differences in response to each phase were also observed. Group level changes seemingly favor CHO-loading; however, it is difficult to judge whether these changes are practically meaningful as they may not be large enough to exceed measurement error and daily biological fluctuations. Before implementation, coaches and competitors should consider individualizing protocols through precompetition testing and visually assessing changes in physique.