http://creativecommons.org/licenses/by-nc-nd/4.0/legalcode Quadriceps femoris cross-sectional area and specific leg strength: relationship between different muscles and squat variations application/pdf 595625 bytes PeerJ PeerJ – the Journal of Life & Environmental Sciences 2021 Keywords: Range of motion, External load, Bioelectrical impedance, Dempster’s method, Deepsquat, Parallel squat eng Којић, Филип https://phaidrabg.bg.ac.rs/o:26133 doi:10.7717/peerj.12435 ISSN: 2167-8359 info:eu-repo/semantics/article Abstract: Background. The aim was to determine the relationship between the cross-sectionalarea of the quadriceps femoris and strength performance in the deep and parallel barbellsquat.Methods. The sample included 16 university students (seven female, 24.1±1.7 years).Muscle strength was expressed as external load, including the one-repetition maximumand the body mass segments involved (calculated according to Dempster’s method).The cross-sectional area of the quadriceps femoris muscles was determined usingultrasound, while leg muscle mass was measured using the Bioelectrical Impedancemethod.Results. The cross-sectional areas of the three vastii muscles and leg muscle massshowed moderate to strong correlation with external load in both squat types (r=0.509–0.873). However, partial correlation (cross-sectional area of quadriceps femorismuscles were controlled) showed significant association only between leg muscle massand deep squat (r=0.64,p<0.05). The cross-sectional area of the vastus lateralisshowed a slightly higher correlation with external load in the parallel than in the deepsquat (r=0.67,p<0.01vs. r=0.59,p<0.05). The regression analysis extracted thevastus medialis cross-sectional area as the most important factor in manifesting strength(parallel squat:R2=0.569; deep squat:R2=0.499, bothp<0.01). The obtained resultssuggest that parallel squat strength depends mainly on the cross-sectional area of thevastii muscles, while it seems that the performance in the deep squat requires anadditional engagement of the hip and back extensor muscle groups. https://peerj.com/articles/12435/