Purpose:
The proposal to eliminate body weight (BW) subcategories in senior rowing at the 2028 Olympic Games may impact smaller-scale competitions, particularly in the junior category, favouring heavier athletes due to the contribution of BW to rowing biomechanics. Aim: To examine whether BW subcategories can influence performance in junior rowers.

Methods:
In this cross-sectional study, the National Rower Evaluation System data set was assessed and data from 235 rowing athletes (171 males and 64 females) in the under-seventeen and under-nineteen categories were analysed comparing anaerobic and aerobic power, strength and endurance within the BW subcategories (cut-off points for defining the subcategories: lightweight – male ≤ 72.5 kg, female ≤ 59 kg; heavyweight – male > 72.5 kg, female > 59 kg). Sprint speed (100-m/500-m) and endurance performance in competition distances (2000-m/6000-m) were evaluated using rowing ergometry. Muscle strength in bench-row (BR), bench-press (BP), squat, and deadlift was determined by one-repetition maximum (1RM).

Results:
At 100 m, higher BW and BR strength improved performance in both sexes. Lightweight athletes were 30.5% slower than heavyweight counterparts. At 500 m, BW, BR strength, and squat strength significantly influenced time in both sexes; however, female athletes performed 9.2% slower than males. At 2000-m, only the weight subcategory and its interaction with sex were significant, favouring heavyweight male rowers. No relevant associations were found at 6000-m.

Conclusions:
Body weight, upper-body pulling strength (bench row), and lower-body strength (squat) influence performance in short- and middle-distance events, regardless of sex. The advantage of heavier and stronger athletes does not persist over longer distances.