Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P49. Effects of lower extremity fatigue and gender on unanticipated landing performance in a recurrent low back pain population

Abstract

BACKGROUND CONTEXT Recurrent low back pain (rLBP) commonly affects the recreational and professional athlete alike, and correlation between rLBP and lower extremity injury has been well established. Previous data have shown strong correlation between a history of back pain and altered landing mechanics, trunk and lower extremity kinematics and kinetic factors all associated with increased lower extremity injury. Additionally, there has been direct proven correlation between neuromuscular core training programs and a decrease in lower extremity ligamentous injuries. Fatigue has also been proven to negatively affect trunk and lower extremity neuromuscular control, which may predispose to lower extremity injury. Well reported gender differences in lower extremity kinetics and kinematics are also known to alter propensity for injury. The complex interplay between these various factors is continuously being studied. Proper understanding of these risk factors for spine and leg injuries is imperative in establishing proper neuromuscular control rehabilitation and training programs to mitigate the risks of lower extremity injury, especially in patients with a history of low back pain. PURPOSE To determine the effects of fatigue and gender on trunk and knee mechanics, neuromuscular control, and ground reaction force (GRF) during drop vertical jump (DVJ) following by unanticipated landing or cutting in a population with rLBP. STUDY DESIGN/SETTING A prospective concurrent control cohort study. PATIENT SAMPLE Thirty-two adults with rLBP. OUTCOME MEASURES 3D knee and trunk motion, knee moments, and GRF. METHODS All test patients were fitted with a full body marker set. Surface EMG electrodes were placed bilaterally on trunk and lower extremity muscles. Each patient performed multiple 0.30 m DVJ landing and cutting in nonfatigued and fatigued conditions. RESULTS Fatigue altered landing mechanics with differences in landing performance between genders. For DVJ trials, females had greater knee internal rotation at initial contact (p=.001). Maximum knee flexion was reduced, but knee adduction (p=.026) and internal rotation (p=.009) and trunk flexion (p=.003) were greater at maximum knee flexion. Similar differences were also found during the cutting trials, with the addition of less trunk side flexion (p=.008) in females at maximum knee flexion. Females had smaller knee flexion moments (p=.021) during the DVJ. Fatigue resulted in less trunk flexion (p=.027) at initial contact for the DVJ, and greater trunk extension (p=.038) and trunk side flexion (p=.035) at maximum knee flexion, smaller maximum vertical GRF on the right leg, and maximum knee adduction moment when cutting. CONCLUSIONS Females with rLBP land differently than males and may have increased exposure to biomechanical factors that can contribute to lower extremity injury. Fatigue similarly alters landing and increases exposure to those same factors in this population. The majority of gender and fatigue related differences were consistent for unanticipated landing and cutting activities, which may better simulate actual sports activity. Armed with additional information of movement behaviors associated with increased lower extremity injuries, practitioners can design neuromuscular control training programs for women with rLBP and for men and women during fatigued conditions that serve a protective function and decrease the potential of ACL and other lower extremity injuries.