Background Lower limb strength asymmetry (SA) is monitored to reduce the injury risk in the young player. Asymmetry values values greater than or equal to 15% indicate a potential injury risk (Noyes et al., 1991). Small-Sided Games (SSG) are widespread in youth training but not all load effects have been analyzed (Kunz et al., 2019).

Objective To describe the fatigue effects on lower limb SA values and sprint values after each SSG series.

Design Within subject repeated measures design.

Setting Youth soccer. Patients (or Participants) n=16 regional level young players (12.1±0.9years, 43.8±8.3kg, 147.8±9.3cm)

Interventions (or Assessment of Risk Factors) The sample was evaluated after the warm-up of 15 minutes and 10 minutes of mastery ball exercises, and at the end of each series (3) of 4vs4 (duration: 3 minutes, rec: 2 ‘field: 24x36 meters, with encouragement of staff and 30 balls available) through Hop Test (HT), Side Test (ST), Crossover Test (CT), 5 meters sprint (5M).

Main Outcome Measurements Asymmetry value was calculated using the formula: (Non-Dominant Leg/Dominant Leg)x100 (Ceroni et al., 2012).

Results The results are summarized as follows:

Conclusions The jumps with frontal plane displacement and those on the two planes (the CT is perfomed by jumping simultaneously on the sagittal and frontal plane) have the highest asymmetry values and seem influenced by post-SSG fatigue. Sprint values undergo acute decreases in performance too.