Hamstring strain injuries (HSI) pose a significant problem within English professional soccer accounting for 12% of all injuries (25), with over half (53%) affecting the Biceps Femoris Long Head (BFLH) (70).
To decelerate the extending knee and flexing hip (5, 31, 70) during kicking and late swing phase of gait (33, 59), the hamstrings must undergo intense eccentric loading in a lengthened position (16). Stretching to 110% of its length in upright standing (59), muscle-tendon units of the BFLH maximally elongate (18, 59, 71) with this and adjacent muscle fibres the common site of disruption (5, 51).
On average a 25-man squad sustains 5-7 HSI per season, with 80-90 days and 15 matches missed per club (25, 70). With substantial time loss (6, 27, 40, 51) and considerable financial implications (32), HSI cost clubs approximately £74 million each season or £500,000 per injury (26, 27, 69) with significant absence impacting negatively on team …show more content…
With increased knee extension and a lower BPA associated with increased eccentric hamstring strength, few studies advocate its use due to an inability to accurately and reliably measure when the angle actually occurs. A video based NHE has been proposed to examine BPA with research identifying a significant relationship with isokinetic eccentric hamstring PT, suggesting its use as a field based assessment of eccentric hamstring strength is both valid and reliable (37, 57). More recently, the use of a smartphone application known as ‘DrGoniometer’ has been shown to be reliable when measuring BPA (66) and its use as an easily accessible and reproducible method may be more appropriate than video analysis. However, both methods may overcome the shortcomings associated with more traditional methods of assessing eccentric hamstring strength which can often prove