Effects Of Different Nutritional Supplements On Immunity And Strength Quality Of Athletes

Objective: To observe the effects of four-week glutamine,probiotics,and whey protein supplementation on athletes’ lower limb muscle strength,anaerobic power,and immune function during the training preparation period during the COVID-19 epidemic,and to explore and analyze the effect of nutritional supplements on the promotion of athletes.Strength-related indicators and the efficacy of improving immune regulation function provide scientific and effective reference for athletes to obtain more effective physical training effects and better competitive performance during the normalization of the epidemic.Methods:（1）48 professional athletes of different events were selected as the experimental research objects and randomly divided into nutritional supplement glutamine group（Glutamine Group,GLN）,probiotics group（Probiotics Group,PRO）,whey protein group（Whey Protein Group,WP）and control group（Control Group,CG）,12 people in each group,6 men and 6 men.The glutamine group,the probiotics group and the whey protein group were given glutamine,probiotics,and whey protein supplements for 4 consecutive weeks,respectively,while the control group did not receive any nutritional supplements.（2）Before and after the 4-week test,four indicators of the athletes’ body composition,blood immunological indicators,anaerobic power and isokinetic muscle strength were tested,and the data were compared and analyzed.Results:（1）There were no significant differences in body composition-related indicators（body weight,body fat percentage,lean body mass,muscle mass,and body mass index）between the GLN,PRO,WP,and CG groups before and after the test（P>0.05）.（2）Blood immunology indexes: The blood immunology related indexes of male athletes: the percentage of neutrophils,the percentage of lymphocytes,the GLN group,PRO group,WP group and CG group had no significant changes,P>0.05.IL-13 index,only CG group IL-13 significantly increased,P=0.019;GLN group,PRO group,WP group had no significant change in IL-13,P>0.05.In terms of IL-17 A,IL-4,IFN-γ and IL-6,there was no significant change in GLN group,PRO group,WP group and CG group after intervention,P>0.05.Compared with CG group after the experiment: IL-13 index,GLN group was significantly lower than CG group,P=0.047;PRO was significantly lower than CG group P=0.038;the other indexes had no significant difference,P>0.05.The blood immunology-related indicators of female athletes showed that compared with before and after the experiment: the percentages of neutrophils and lymphocytes had no significant changes in the GLN group,PRO group,WP group and CG group,P>0.05.IL-13 index,only PRO group significantly decreased IL-13,P=0.013;GLN group,PRO group,WP group had no significant change in IL-13,P>0.05.IL-4 index,GLN group significantly decreased,P = 0.033;IL-17 A,IFN-γ and IL-6,GLN group,PRO group,WP group,CG group did not show significant changes after intervention,P> 0.05.Compared with the CG group after the experiment: there was no significant difference in each index,P>0.05.（3）Anaerobic power: Compared with before the test,the relative maximum power of female athletes in the GLN group increased significantly（12.17±2.31 W·kg-1 vs12.96±2.19 W·kg-1,P<0.05）,and the male athletes were relatively The average power increased significantly（8.79±0.65 W·kg-1 vs 9.26±0.54 W·kg-1,P<0.05）,and the male athletes Ppeak/kg in the PRO group increased significantly after the test（12.35 ± 1.85W·kg-1 vs 13.94 ±1.71 W·kg-1）（P<0.05）,there was no significant difference in the indicators of female athletes;no significant difference was found between male and female athletes in WP group;Pmin/kg and Pmean/kg of male athletes in CG group showed a downward trend However,there was no significant difference,and there was no significant difference in the indicators of female athletes.（4）Isokinetic muscle strength test: after the test,there was no statistically significant difference between the 60° knee flexion and 60° knee extension of the athletes in the GLN group（P > 0.05）.There was no significant difference in the indexes of the male athletes in the WP group,but there was no significant difference,and there was no difference in the female athletes;the male athletes in the WP group had no significant difference in the indexes of the female athletes;the right 60-degree knee extension of the male athletes in the CG group decreased significantly（3.87±0.39 N m kg-1 vs 3.34±0.49 N·m·kg-1）（P<0.05）,and other indicators also showed a downward trend.Female athletes ’ right knee flexion 60 degrees and right knee extension 60 degrees decreased significantly（1.46±0.16 N ·m·kg-1 vs 1.36±0.20 N·m·kg-1,2.90±0.47 N·m·kg-1vs 2.75±0.47 N·m·kg-1）（P<0.05）,and the left 60 Knee extension showed a decreasing trend but no significant difference.Conclusion:（1）Four weeks of glutamine supplementation has a certain positive effect on the level of anaerobic endurance of athletes.（2）Four weeks of glutamine and probiotic supplementation had a positive effect on the immune function of athletes （3）Supplementation with probiotics may have a positive effect on the anaerobic work level and the maintenance of muscle strength in male athletes.