Physical training is recommended for obese paediatric populations. We investigated the effects of recreational judo training (JT) upon body composition and distribution, cardiorespiratory fitness, and heart rate variability (HRV) in overweight or obese children. A controlled trial (RBR-9d94td) was conducted with 35 children (8-13 years) assigned into groups according to their body mass index (BMI): eutrophic (EU; n = 15; z-BMI </= +l and >/= -2) and overweight or obese (OB; n = 20; z-BMI > +1 and </= +3). The 12-week JT included 60-min sessions performed 2 times/week at 65-75% maximal heart rate (HR). BMI, waist circumference, blood pressure, HRV, peak oxygen uptake (VO(2peak)), gas exchange threshold (GET), and body fractioning were assessed. Significant reductions in OB (P < 0.05) occurred for whole body and trunk fat (~3%), trunk/limb fat-ratio (~4%), resting HR (~3%), and sympathovagal balance (log LF:HF, ~85%). Increases (P < 0.05) occurred in lean mass (~8%), parasympathetic modulation (log HF, ~4%), VO(2peak) (~5-10%), and VO(2) (~15%), speed (~10%) and slope (~13%) at GET. Markers of cardiorespiratory fitness (relative VO(2), slope and speed at GET) in OB approached EU after JT. In conclusion, a relatively short JT intervention to improved body composition, autonomic modulation, and physical fitness in obese children.