Associations of thigh muscle thickness with cardiorespiratory fitness and ventilatory efficiency in male soccer athletes

Skeletal muscle is crucial for locomotion, metabolic health and represents a substantial portion of the whole body-body mass in athletes. Muscle ultrasound (MUS) has been reported as a reliable and potential method in the quantification of regional skeletal muscles. While previous research has shown a relationship between MUS evaluations and skeletal muscle strength the relationship between thigh muscle thickness and cardio-respiratory capacity evaluated by cardio-respiratory exercise testing (CPET) remains un-explored. In competitive soccer male athletes, body composition parameters, rectus femoris (RF), vastus intermedius (VI) and overall muscle thickness of thigh (MT), were analyzed. Physical capacity was evaluated by CPET. Significant correlations were observed between RF, VI, MT and peak VO2 and VE/VCO2 slope (p < 0.01). Regression analysis showed that RF, VI, MT were independently associated with peak VO2 and VE/VCO2 slope (p < 0.001). Ultrasound measurements of rectus femoris and vastus intermedius is independently associated with cardiopulmonary performance in a population of male athletes. Our findings reveal that greater muscle thickness correlates with higher peak oxygen consumption and improved ventilatory efficiency during maximal exercise testing.