Comparison of different methods of core muscle fatigue on lower extremity function tests among female athletes

Despite the importance of core muscles in kinetic chains, the importance of each muscle compared to others has rarely been investigated. The purpose of this study was to compare the effect of each core muscle fatigue on lower extremity function tests. This quasi-experimental study with a pretest-posttest design was performed on 30 physical educations, female students with the mean age of 23.46±2.54 years, mean height of 1.63 ± 0.05 cm, and mean weight of 55.61 ± 7.67 kg. The participants performed lower extremity function tests at the first session in normal conditions (without fatigue), and at the next sessions (second, third and fourth) after performing a fatigue protocol of selected core muscles and the results were compared. In order to analyze the data paired samples t-test and repeated measures ANOVA were performed in SPSS. Core muscle fatigue (flexor's fatigue, trunk extensor fatigue and hip abductor fatigue), significantly reduced lower extremity function test scores (P<0.05).  Overally, a decrease in test scores after three jumps, single-leg hip abductor muscle fatigue with the large effect size (0.82) trunk extensor and flexor muscles to fatigue was observed. Function of core muscles affects lower extremity function tests because core muscle fatigue causes a reduction in the reaching distance in anterior direction and increases the number of errors in all the components of Y balance test. Exercises that can provide an improvement in core muscles endurance and their ability to cope with fatigue are recommended and can be used by coaches to prevent injuries.