Higher mean heart rate intensity (180.9 bpm) during 3v3 games was associated with lower cardiovascular load variability (CV% 1.97%) compared to 5v5 games (CV% 2.61%).
Does game format (3v3 vs 5v5), intermittent aerobic capacity, or mean heart-rate intensity predict cardiovascular load variability during small-sided soccer games in youth players?
Higher mean heart rate intensity during small-sided soccer games is associated with lower bout-to-bout heart rate variability, independent of the game format or the player's baseline aerobic capacity.
Using a randomized, counter-balanced cross-over design in under-19 male soccer players, this study examined whether within-player cardiovascular load variability during small-sided games (SSGs) is more strongly associated with game format (3v3 vs 5v5), intermittent aerobic capacity, or the mean heart-rate intensity achieved across bouts. Sixty players (17-19 years) completed two weeks of SSGs, performing four 3-min bouts per format with 2-min recovery. Heart rate (HR) was recorded continuously. Cardiovascular variability for each format was quantified for each player as the coefficient of variation of bout-level HRmean across the four 3-min bouts (CV% = SD/mean × 100). Intermittent aerobic capacity was assessed using the Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1). Linear mixed-effects modelling examined the independent associations between format, Yo-Yo IR1 performance, mean HR intensity, and CV% was log-transformed to address skewness and improve model residuals. Paired comparisons showed that HRmean was higher in 3v3 than in 5v5 (p 0.001), whereas between-player variability (CV%) was higher in 5v5 than in 3v3. Specifically, CV% was 1.97 ± 0.81% in 3v3 versus 2.61 ± 1.21% in 5v5, while mean HR intensity was 180.9 ± 2.8 bpm in 3v3 compared with 173.6 ± 3.6 bpm in 5v5. The mixed model indicated that mean HR intensity was the only significant predictor of cardiovascular variability (β = -0.027, 95% CI = -0.050 to -0.005, p = 0.019). Neither SSG format (β = 0.056, p = 0.618) nor Yo-Yo IR1 performance (β = -0.00008, p = 0.385) were significant predictors. The fixed-effects structure explained 13.6% of the variance (marginal R2 = 0.136). Within the training conditions studied, higher mean HR intensity was associated with lower bout-to-bout HR variability. However, the fixed effects explained a modest proportion of variance, indicating that additional unmeasured factors likely contribute to cardiovascular load variability.
Kisilewicz et al. (2026) studied this question. Higher mean heart rate intensity (180.9 bpm) during 3v3 games was associated with lower cardiovascular load variability (CV% 1.97%) compared to 5v5 games (CV% 2.61%).