Biceps femoris long head muscle architecture in professional male soccer players with a recent history of T-junction hamstring injury: a preliminary case-control study in an English Premier League club

Objectives To describe and compare biceps femoris long head (BFlh) muscle architecture between limbs with and without a recent history of T-junction hamstring injury. Design Case-control study. Setting English Premier League club. Main outcome measures Participants were 30 professional male soccer players, including 5 cases with recent history of unilateral T-junction hamstring injury and 25 controls with no recent history of any hamstring injury. Participants had their BFlh fascicle length (FL), pennation angle (PA) and muscle thickness (MT) assessed bilaterally using wide-field-of-view ultrasound. Paired t-tests compared FL, PA and MT between previously injured (left) BFlh and contralateral uninjured (right) BFlh within cases. Un-paired t-tests compared left BFlh – right BFlh (asymmetry) in these measures between the case and control groups. Results Within cases, MT was significantly less in previously injured compared to contralateral uninjured BFlh (p < 0.01; mean paired difference [95%CI] = -0.48 cm [-0.59 cm to −0.36 cm]). Asymmetry in BFlh muscle thickness was significantly larger in the case group compared to control group (p < 0.01; between-group mean difference [95%CI] = −0.51 cm [-0.64 cm to −0.37 cm]). BFlh FL and PA did not differ significantly within cases, or between the case and control groups. Conclusion Between-limb deficits in BFlh MT exist following T-junction hamstring injury.