Neuromuscular and Biomechanical Adaptations Following a 15-Week CrossFit-Based Functional Training Program in Competitive Sambo Athletes

Background: Combat sports require athletes to repeatedly perform explosive actions under conditions of fatigue, demanding high levels of neuromuscular coordination, reactive agility, and intermittent effort capacity. This study examined changes in biomechanical and neuromuscular performance over a 15-week period during which competitive Sambo athletes completed a CrossFit-based functional training program alongside their regular sport-specific training. Methods: Forty male Sambo athletes (22.4 ± 2.6 years) completed a longitudinal repeated-measures intervention consisting of three weekly CrossFit-based sessions integrated into regular sport-specific training. The program was periodized across four progressive mesocycles emphasizing functional strength, explosive power, reactive agility, and fatigue resistance. Pre- and post-intervention assessments included upper- and lower-limb reaction speed, vertical jump height, repeated jump endurance, reactive agility, grip endurance, body-weight squat performance, Romanian deadlift repetitions, and the Special Judo Fitness Test (SJFT). Statistical analyses included paired-samples t-tests or Wilcoxon signed-rank tests with Benjamini–Hochberg false discovery rate correction (α = 0.05). Results: Significant post-intervention improvements were observed in most performance variables. Upper- and lower-limb reaction performance improved by 22.9% and 9.7%, respectively (p < 0.001), while vertical jump height increased by 11.4% and repeated jump endurance by 16.6% (p < 0.001). Reactive agility time decreased by 6.6% (p < 0.001), indicating faster cognitive-motor responsiveness. Functional strength improved substantially, with increases of 43.7% in body-weight squat performance and 71.9% in Romanian deadlift repetitions (p ≤ 0.001). Grip endurance improved by 6.3% (p = 0.007), whereas maximal handgrip strength showed no significant changes. The SJFT index decreased by 5.0% (p < 0.001), reflecting enhanced intermittent effort efficiency and fatigue tolerance. Large effect sizes were identified for upper-limb reaction speed (d = 1.42), explosive endurance (d = 1.46), and reactive agility (d = 0.96). Conclusions: Over the 15-week study period, participation in a CrossFit-based functional training program integrated into regular Sambo practice was associated with improvements in several biomechanical and neuromuscular performance outcomes, including reaction performance, explosive power, agility, muscular endurance, and sport-specific work capacity. However, because the study did not include a control group, these changes cannot be attributed exclusively to the CrossFit-based intervention. Controlled studies are required to distinguish intervention-specific effects from seasonal training adaptations, continued sport-specific practice, and test familiarization.