Thursday Morning Poster Presentations: Posters displayed from 7:30 a.m.–12:30 p.m.: One-hour author presentation times are staggered from 8:30–9:30 a.m. and 9:30–10:30 a.m.: D-30 Free Communication/Poster – Sport Biomechanics: THURSDAY, JUNE 1, 2006 2:00 PM – 5:00 PM ROOM: Hall B
PURPOSE: Female athletes have a significantly higher incidence (ten fold) of ACL injuries compared to men in non-contact sports. It is thought that activities such as landing a jump or cut may result in injury or different muscle firing patterns may be involved. Little research has been performed on the recreational athlete during these types of activities and since the number of particpants far exceeds those in organized collegiate level sports, it is imperative to investigate this group.
METHODS: 15 female and 15 male recreational athletes with no history of ACL injury participated. Surface EMG electrodes were placed over the Gluteus Maximus, Gluteus Medius, VMO, Semitendinosis, Biceps Femoris, Gastrocnemius, Peroneus Longus Muscles and data sent to Noraxon software. Subjects performed MVIC's at each muscle and this value used to normalize for use during the activities which followed. This included: drop landings from two heights, jump landings, cut to L/R, deceleration. Values were recorded form 200 msec pre-contact through 250 msec post-contact with force plate (AMTI). Mean and peak values (in mV) were recorded as calculated on the dominant leg and converted to %MVIC for each activity. MANOV was used to analyze the data, plyometric training instituted for 4 weeks, and an identical post-test performed.
RESULTS: Deceleration-showed that in the Gluteus Medius the women utilized a mean of 134% (SE 17%) of MVIC compared to men 73.4% (SE 13.6%) (p=0.01); Peak Gluteus Maximus post-contact males used a mean peak MVIC of 110 (SE19.3%) while the women used 209% (27.8%) MVIC (p=0.007); cutting to the left also demonstrated a gender difference in the Biceps Femoris (p=0.039) with an observed power of 0.580 and Gluteus Medius during the pre-contact phase following training (p=0.048) with the women activating at a higher level than the men. CoNCLUsIoNs: Inadequate time of hamstring and other core muscle contraction along with increased quadricep use may place both genders in a position of risk for ACL injury secondary to anterior tibial shear forces. Proper training is warranted and plyometric training and drills such as backward running may assist to reduce this risk.