Introduction Hypothesis and Purpose Statement 1. Arampatzis A, Bruggemann G, Metzler V. The effect of speed on leg stiffness and joint kinetics in human running. J Biomech. 1999;32(12): doi: /S (99) Belli A, Kyrolainen H, Komi PV. Moment and power of lower limb joints in running. International Journal of Sports Medicine. 2002;23(2): Dorn TW, Schache AG, Pandy MG. Muscular strategy shift in human running: Dependence of running speed on hip and ankle muscle performance. J Exp Biol. 2012;215(11): doi: /jeb Schache AG, Blanch PD, Dorn TW, Brown NAT, Rosemond D, Pandy MG. Effect of running speed on lower limb joint kinetics. Med Sci Sports Exerc. 2011;43(7): doi: /MSS.0b013e Van Caekenberghe I, Segers V, Aerts P, Willems P, De Clercq D. Joint kinematics and kinetics of overground accelerated running versus running on an accelerated treadmill. Journal of the Royal Society Interface. 2013;10(84): doi: /rsif Joint Kinetics Of Accelerated Running Daniel J. Schuster 1, Shane M. Rabideau 1, Patrick Rider 1, John Willson 2, Anthony S. Kulas 3 and Paul DeVita 1 1 Department of Kinesiology, 2 Department of Physical Therapy, 3 Department of Health and Promotion, East Carolina University, Greenville, North Carolina Running biomechanics are well established in terms of ground reaction forces, joint torques, and joint powers as is the direct relationship between these variables and running speed. Many studies have investigated the effects of these variables when running velocity was increased in constant state increments (Arampatzis et al, 1999; Belli et al, 2002; Schache et al, 2011, Dorn et al, 2012). Running velocity in an athletic contest is rarely held constant. Athletes go through periods of acceleration and it is these periods that are less investigated. Van Caekenberghe et al (2013) performed one of the few research studies investigating the acceleration period of running. The results showed that there was no increase in the joint torques at the hip, knee, and ankle by the participants during the acceleration period of the trial on the instrumented treadmill.Methods Conclusion References It was hypothesized that that there will be an increase in the magnitude of the GRFs and joint torques and powers with each step during accelerated running. The purpose of this study was to quantify lower extremity joint torques and powers during constant speed running and during running while accelerating at two rates of acceleration between a baseline velocity of 2.50 ms -1 to a maximal velocity of 6.00 ms -1. Only torques are presented here. Figure 7. Participant preparation and testing and V3D analysis. Results In contrast to a previous report, our data suggest that hip and ankle torques do increase during accelerated running on a step by step basis. Knee torque results need further study but may be directly related to acceleration step number albeit not as strongly as hip and ankle torques. (6) PROTOCOL VIDEO V3D MODELResults Maximum joint torques at hip, knee, and ankle had correlations of r=0.979, 0.699, and respectively with step number in A1 (all p<.05). Maximum joint torques at hip, knee, and ankle had correlations of r=0.903, , and respectively with step number in A2 with only hip and ankle increasing significantly (p<.05) during accelerated running. Table 1 below presents these values along with the initial and final constant state velocities. The figures show the mean peak joint torques for the hip, knee and ankle in each condition. Increases through the acceleration period are evident at the hip and ankle. 6 of 20 planned participants were analyzed on an instrumented treadmill while accelerating at 0.40 ms -2 (A1) and 0.80 ms -2 (A2) from the initial to final velocities. Inverse dynamics were used to determine lower limb joint torques and powers using ground reaction forces and kinematic data collected by 3D motion capture. Correlation and regression analyses were used to identify the relationships between mean, maximum hip, knee, and ankle torques and step number during the acceleration phase. Figure1: A1 Mean Peak Hip Joint Torques Figure 2: A1 Mean Peak Knee Joint Torques Figure 3: A1 Mean Peak Ankle Joint Torques A1A2 Pre Accel AccelPost Accel Pre Accel AccelPost Accel Hip * * Knee * * Ankle * * Table 1: Step Number Correlations Figure 4: A2 Mean Peak Hip Joint Torques Figure 5: A2 Mean Peak Knee Joint Torques Figure 6: A2 Mean Peak Ankle Joint Torques PROTOCOL VIDEO V3D MODEL