Ultrasound assessment of hamstring muscle size using posterior thigh muscle thickness

<jats:title>Summary</jats:title><jats:p>Several studies have investigated the relationship between ultrasound‐measured muscle thickness (<jats:styled-content style="fixed-case">MT</jats:styled-content>) and individual muscle cross‐sectional area (<jats:styled-content style="fixed-case">CSA</jats:styled-content>) and muscle volume (<jats:styled-content style="fixed-case">MV</jats:styled-content>) in extremity and trunk muscles; however, the hamstring muscle has not been studied. The purpose of this study was to examine the relationship between posterior thigh <jats:styled-content style="fixed-case">MT</jats:styled-content> by ultrasound and the muscle <jats:styled-content style="fixed-case">CSA</jats:styled-content> and <jats:styled-content style="fixed-case">MV</jats:styled-content> of the hamstring obtained by magnetic resonance imaging (<jats:styled-content style="fixed-case">MRI</jats:styled-content>). Ten young women aged 20–31 had <jats:styled-content style="fixed-case">MT</jats:styled-content> measured by ultrasound at three sites on the medial anterior (50% of thigh length; <jats:styled-content style="fixed-case">TL</jats:styled-content>) and posterior (50% and 70% of <jats:styled-content style="fixed-case">TL</jats:styled-content>) aspects of the thigh. On the same day, a series of continuous muscle <jats:styled-content style="fixed-case">CSA</jats:styled-content> along the thigh was measured by <jats:styled-content style="fixed-case">MRI</jats:styled-content>. In each slice, the anatomical <jats:styled-content style="fixed-case">CSA</jats:styled-content> of the hamstring (biceps femoris, semitendinosus and semimembranosus) and quadriceps muscle was analysed, and the <jats:styled-content style="fixed-case">CSA</jats:styled-content>s at 50% and 70% of <jats:styled-content style="fixed-case">TL</jats:styled-content> and maximal <jats:styled-content style="fixed-case">CSA</jats:styled-content> of the hamstring (<jats:styled-content style="fixed-case">CSA</jats:styled-content><jats:sub>max</jats:sub>) were determined. <jats:styled-content style="fixed-case">MV</jats:styled-content> was calculated by multiplying <jats:styled-content style="fixed-case">CSA</jats:styled-content> by slice thickness. A significant correlation was observed between posterior 50% <jats:styled-content style="fixed-case">MT</jats:styled-content> and 50% hamstring <jats:styled-content style="fixed-case">CSA</jats:styled-content> (<jats:italic>r</jats:italic> = 0·848, <jats:italic>P</jats:italic> = 0·002) and between posterior 70% <jats:styled-content style="fixed-case">MT</jats:styled-content> and 70% hamstring <jats:styled-content style="fixed-case">CSA</jats:styled-content> (<jats:italic>r</jats:italic> = 0·679, <jats:italic>P</jats:italic> = 0·031). Posterior 50% <jats:styled-content style="fixed-case">MT</jats:styled-content> (<jats:italic>r</jats:italic> = 0·732, <jats:italic>P</jats:italic> = 0·016) and 50% <jats:styled-content style="fixed-case">MT</jats:styled-content>x<jats:styled-content style="fixed-case">TL</jats:styled-content> (<jats:italic>r</jats:italic> = 0·873, <jats:italic>P</jats:italic> = 0·001) were also correlated to hamstring <jats:styled-content style="fixed-case">MV</jats:styled-content>. Anterior:posterior 50% thigh <jats:styled-content style="fixed-case">MT</jats:styled-content> ratio was correlated to <jats:styled-content style="fixed-case">MV</jats:styled-content> ratio of quadriceps and hamstring muscles (<jats:italic>r</jats:italic> = 0·803, <jats:italic>P</jats:italic> = 0·005). Our results suggest that posterior thigh <jats:styled-content style="fixed-case">MT</jats:styled-content> reflects hamstring muscle <jats:styled-content style="fixed-case">CSA</jats:styled-content> and <jats:styled-content style="fixed-case">MV</jats:styled-content>. The anterior:posterior <jats:styled-content style="fixed-case">MT</jats:styled-content> ratio may serve as a surrogate for <jats:styled-content style="fixed-case">MV</jats:styled-content> ratio of quadriceps and hamstring.</jats:p>