Effects of different small-sided games on blood lactate and GH/IGF-1 axis responses in young soccer players

Abstract

Soccer and its intense workouts cause lactate accumulation and extensive metabolic changes. This study, therefore, aimed to compare the percentage of maximum heart rate (%HRmax), blood lactate, growth hormone (GH), and insulin-like growth factor‑1 (IGF-1) responses across different formats of small-sided games (SSG) in young soccer players. Twenty-four soccer players (mean age: 17.1 ± 1.12 years, weight 67.28 ± 1.65 kg and body mass index 20.8 ± 1.18 kg/m2) were randomly divided into three equal groups, including control, 2 vs. 2 (8 periods of 2 min separated by 1 min of passive recovery, with a pitch of 20 m × 25 m) and 4 vs. 4 (4 periods of 4 min separated by 2 min of passive recovery, with a pitch of 28 m × 35 m). Blood samples were taken immediately before and after small-sided games. The results showed that the heart rate increased significantly in young soccer players at different minutes of SSG (p ≤ 0.05). The comparison of these two SSG did not show any significant differences on lactate and somatotropic hormone concentrations (p > 0.05), although each alone significantly increased lactate, GH and IGF‑1 levels compared to control group (p < 0.05). Hence, it can be concluded that due to the sufficient intensity of these two modes of SSG, the cellular relationship between the GH/IGF‑1 axis and lactate helps improve the physiological capacity of young soccer players. However, further studies were needed to consider more accurate effects of these variables (lactate, GH and IGF-1) with two SSG modalities (2 vs. 2 and 4 vs. 4).