Comparison of Hamstring : Quadriceps ( H : Q ) Ratios and Peak Torque per Body Weight of Eccentric Hamstring Strength for Division by Side

Eccentric hamstring strength and 2 types of hamstring to quadriceps ratios (conventional, functional) at 2 velocities were examined for 42 athletes with a history of hamstring injury. The authors used the Biodex System 3 for eccentric/ concentric knee fl exion and extension at 1.05 and 3.14 rad·s-1 and knee fl exion endurance of 30 reps at 3.14 rad·s-1. The authors assessed the diff erences between side (injured or uninjured) and division (Division I or III) for the peak torque per body weight and ratio variables and included repetitions (1-5 and 26-30) for the endurance measurement. The authors found division diff erences for peak torque per body weight at 1.05 rad·s-1 (Division I was higher) and for division for functional hamstring to quadriceps ratios (Division III was higher at 3.14 rad·s-1 only) and repetition changes (repetitions 1-5 were higher than repetitions 26-30) for total work. The injured side is comparable with the uninjured side when examining values at approximately 9 months from injury; however, differences should be examined immediately on return to play. Hamstring injuries are one of the most commonly occurring injuries in sports participation.1-7 The National Collegiate Athletic Association Injury Surveillance System (2000-2001 through 2003-2004) reported that lower extremity muscle strains were one of the leading athletic-related injuries.2 In addition, incidence of hamstring injury was second to knee injuries in a 10-year study of all National Football League training camps3 and accounted for 12% to 47% of all injuries sustained during a season from major league soccer teams to Gaelic football players.1,5,8 The frequency of hamstring injury is further compounded by the fact that individuals who incur a hamstring strain have a reinjury rate as high as 34%,1 and many of these injuries occur within 1 year of return to play. The most common mechanisms of injury involve eccentric contraction of the hamstring muscle group during the latter part of the swing phase of gait or running in which the hamstring muscles reach their maximal length.9,10 Previous studies4,6,8,11-15 have identifi ed multifactorial risks associated with hamstring injuries. These factors include muscle attachment site and anatomy of the muscle,16-18 history of injury,12,14,19 age,19,20 fl exibility,21-24 fatigue,23 poor lumbar and core strength,4,25-27 insuffi cient warm-up,28-31 muscle imbalance,13,16,32 hamstring and quadriceps strength comparisons,10,33,34 scar tissue,1,35-38 and overall strength weakness.6,21,22,32,33,39-42 Although there are many risk factors associated with individuals predisposed to hamstring injury, eccentric hamstring strength defi cits appear to be one of the leading factors related to recurrent hamstring injury.10,15,39,43 Many hamstring rehabilitation protocols include eccentric strength components; however, return-to-play criteria often do not include specifi c assessment of eccentric strength. This may be due to the availability of equipment or because functional or sports-specifi c tests that target eccentric strength are limited and not used.12,44,45 There also may be differMs Doherty, Dr Van Lunen, and Ms Ismaeli are from Old Dominion University, Norfolk, Virginia; Mr Krzyzanowicz is from Concord College, Athens, West Virginia; and Dr Onate is from Ohio State University, Columbus, Ohio. Received: April 26, 2010 Accepted: March 2, 2011 Posted Online: April 15, 2011 The authors have no fi nancial or proprietary interest in the materials presented herein. Address correspondence to Bonnie L. Van Lunen, PhD, ATC, Old Dominion University, Department of Exercise Science, Sport, Physical Education, and Recreation, Spong Hall, Room 104C, Norfolk, VA; e-mail: bvanlune@odu.edu. doi:10.3928/19425864-20110415-01