Differential increase in the thickness of abdominal muscles during different squat exercises in college athletes

BACKGROUND: The squat exercise is frequently used to develop muscle strength of the lower back, hip, and knee regions to improve physical performance. OBJECTIVE: To investigate the effects of squat exercises involving three types of isometric hip contractions and two types of wall conditions on the thickness of abdominal muscles in college athletes. METHODS: Twenty-seven college athletes, 17 men and 10 women, took part in the study. Subjects performed the standard squat without hip contraction, the isometric hip adduction squat, and the isometric hip abduction squat with and without using a wall. Abdominal thickness was measured with an ultrasound and presented as muscle thickness ratio. RESULTS: The transversus abdominis (TrA) and internal oblique (IO) thickness ratio was significantly greater during the isometric hip adduction squat exercise compared to the standard and isometric hip abduction squat exercises. The TrA and IO thickness ratio in the isometric hip abduction squat exercise was significantly higher than that in the standard squat exercise. The external oblique (EO) thickness ratio was significantly higher in the squat exercise without wall compared to the squat exercise with wall. CONCLUSIONS: Isometric hip adduction squat exercise may be an effective method for increasing the TrA and IO thickness ratio while performing the squat exercise without wall may help increase the EO thickness ratio.