The Impact of the Experimental ‘Grappler Quest’ Training on the Structural Profile of Brazilian Jiu-Jitsu Athletes—A Randomized Controlled Trial

Background: The effectiveness of innovative training interventions has not yet been adequately tested in Brazilian jiu-jitsu (BJJ). This study aimed to evaluate the effectiveness of the Grappler Quest (GQ) training program on the structural profile of BJJ athletes and to examine the relationship between training experience and outcomes. Methods: A randomized controlled trial involving 44 BJJ athletes was conducted to assess the effects of an 8-week training program. The experimental group (EXP; n = 22) followed the GQ program (training stations) while the control group (CON; n = 22) followed a standard training cycle. The structural profile was assessed before and after the intervention, and the relationship between training experience and GQ effects was analyzed. Results: In the EXP group, significant improvements were observed across all structural variables (p < 0.05), with the largest increases in chest mobility (+1.03 cm), thigh circumference (+1.5 cm), and the muscularity of the upper arm (+1.48), lower leg (+1.33), and thigh (+2.60). The greatest reductions occurred in fat tissue (FM% −1.76; FM kg −1.55; sum of three skinfolds −1.21 mm; p < 0.001), with favorable somatotype changes. In the EXP group, training experience significantly correlated with outcomes: positively with fat tissue (rs = 0.49–0.64) and negatively with muscle mass (rs = −0.44–0.81). Conclusions: GQ improved the structural profile of BJJ athletes, with its effectiveness showing a stronger correlation with the progress of athletes with shorter training experience. The GQ strategy is recommended as an effective addition to BJJ training.