1. INTRODUCTION Positive Ankle Work is Decreased in Peripheral Arterial Disease Before the Onset of Claudication Pain Before the Onset of Claudication Pain Alek Z. Diffendaffer 1, Jennifer M. Yentes, 1 Shane R. Wurdeman 1, Iraklis I. Pipinos 2,3, Jason M. Johanning 2,3 Sara A. Myers 1 METHODS DISCUSSION ACKNOWLEDGEMENTS  Peripheral arterial disease (PAD) is characterized by atherosclerotic blockages restricting blood flow to the lower extremities that causes pain and discomfort which is typically brought on by physical activity (Figure 1).  Several previous studies have found decrements in ambulation associated with PAD, such as joint moments and powers before and after the onset of claudication pain [1-4].  While patients with PAD exhibit reduced joint powers while compared to velocity matched controls, they are able to ambulate as similar speeds [3].  The purpose of this study is to indicate if differences in joint work (negative, positive, total) are different when comparing patients with PAD and healthy speed matched controls. RESULTS Funding was provided by the NASA Nebraska Space Grant Fellowship and the University of Nebraska- Omaha Graduate Research and Creative Activity (GRACA) grant.  From this study patients with PAD exhibit a 26% reduction in positive ankle joint work as compared to their healthy counterparts during the stance phase of the gait cycle and the total ankle joint work was also decreased as compared to the healthy controls in this study.  This may be due to the limited ability of the ankle plantarflexors being able to concentrically contract to propel the body forward and lead the leg into swing phase.  The amount of work absorption and generation prior to the onset of claudication pain may indicated a reduction in energy transfer as well as muscular function in the lower extremity of the patients with PAD.  Future rehabilitation for patients with PAD will need to focus on reducing the deficits caused by the impairments found in the ankle plantarflexor muscles of the lower extremity. nAge (years)Mass (kg)Height (cm)Velocity (m/s) Controls569.0 + 4.679.4 + 8.1175 + 1.61.30 +.09 PAD566.6 + 6.2103 + 18.5178 + 9.31..16 +.07  Hypothesis: Due to decreases in the previous literature with respect to moments and powers in patients with PAD, it is hypothesized that the same decreases in joint work will occur. Figure 1. Atherosclerotic blockages in the arteries limiting oxygenated blood to the lower extremity. Figure 2. Representative ankle power for healthy controls (red) and patients with PAD (blue) plotted against percent of stance. The integral or area under the curve of each power plot is indicative of joint work (Joules). Independent t-tests were used to compare the joint work (negative, positive, and total) values between groups. Hip Note: All values in joules (J). * p < 0.05; significant difference between healthy controls and patients with PAD 1 University of Nebraska at Omaha, Omaha, Nebraska 2 Omaha Veterans’ Affairs Medical Center, Omaha, Nebraska 3 University of Nebraska Medical Center, Omaha, Nebraska REFERENCES 1.Koutakis P, et al. J Vasc Surg 52, 340-347, 2010. 2.Koutakis P, et al. J Vasc Surg 51, 80-88, 2009. 3.Wurdeman S, et al. Gait & Posture 36, 506-509, 2012. 4.Wurdeman S, et al. Med Eng Phys 34, 1421-1426, 2012. Five trials of walking were collected for each limb Five trials of walking were collected for each limb Each subject rested for one minute between each trial Patients with PAD Healthy Controls Knee Ankle Negative Positive Total *