2.3. Experimental Design
The main objective of this experiment was to compare the effects of prebiotic and synbiotic supplements on the immune functions of football players after daily high-intensity training and a one-time strenuous exercise. The inclusion criteria for the subjects were as follows: no injuries during the experiment, no consumption of any prebiotics, probiotics, synbiotics, or fermented products (yogurt or other foods), and no consumption of any medications or supplements. Participants were asked to follow their regular diet for two weeks before the survey and during the programme. Prior to the experiment, all subjects were familiarised with the study process. Each participant signed an informed consent form and ensured that they could successfully complete all tests. The experimental protocol was approved by the Ethics Committee of Beijing Sport University (no. 2020167H). The participant characteristics revealed no observable differences between the SG group and PG group in terms of height, weight, age, maximal oxygen uptake (VO2max), or body mass index (BMI) (