Manny Azizi Postdoctoral Researcher
Ph.D., Organismic and Evolutionary Biology, University of Massachusetts, Amherst, 2005.
Thesis title: “ Biomechanics of salamander locomotion.”
The primary theme of my research is the form and function of the musculoskeletal system in vertebrates. Specifically I am interested in how the spatial organization (architecture) of muscle fibers determines the mechanical output of muscle-tendon units during locomotion. My work combines geometric modeling, in situ physiological techniques and in vivo measurements during locomotion in order to better understand the functional significance of muscle architecture. By developing a comprehensive understanding of muscle architecture, I aim to integrate the mechanical demands of locomotion with the physiological constraints of the vertebrate sarcomere. My doctoral work was primarily focused on the form and function of segmented axial musculature in fishes and salamanders during swimming. For my post-doctoral work I have been using wild turkeys as a model system for understanding the dynamic behavior of pinnate muscles during running. In addition to my primary research interests, I also have ongoing collaborations focused on the ontogeny of locomotor performance in amphibians, phenotypic plasticity of locomotor structures, and underwater walking in tetrapods.

Greg Sawicki, Postdoctoral Researcher
Ph.D., Kinesiology and Mechanical Engineering, University of Michigan, Ann-Arbor, 2007.
Thesis title: “Mechanics and energetics of walking with powered exoskeletons”

My post-doctoral research will focus on the mechanics, energetics and neural control of the muscle-tendon complex. I will use simple mechanical models to explore the role of tendon in shaping the muscle-length trajectory during cyclic contraction. Model predictions will be tested experimentally in (1) the human Achilles tendon-triceps surae complex (using ultrasound) and (2) the bullfrog Achilles tendon-plantaris complex (using direct measurements).

My ultimate goal is to establish an academic research program using biological principles to develop better lower-limb robotic devices to assist both healthy and impaired human locomotion. -->Link to Greg's Website

Tonia Hsieh, Postdoctoral Researcher
Ph.D., Biology, Harvard University, 2005.
Thesis: “Biomechanics of Locomotion at the Air-Water Interface”
I am interested in understanding the control and biomechanics of locomotion through complex environments. My research incorporates tools from biology and engineering to examine locomotion at both the level of muscle and whole-animal function. Studying animals with unusual or extraordinary locomotor capabilities sheds light on how the form of a locomotor system may constrain or dictate locomotor function. Results from these studies are easily applied on a broader scale towards understanding human locomotion and designing tools relevant to human health. My doctoral work concerned the effects of surface properties on locomotion and the function of locomotor structures. Specifically, I studied how a soft surface such as water affects locomotor mechanics in water-running basilisk lizards and how an amphibious fish walks about on land with its fins. My postdoctoral research delves into the inner workings of muscle mechanics and physiology, focusing on how elastic energy storage and intrinsic muscle properties play a role in enabling the high-powered accelerations of jumping frogs.

Jackie Parente, Masters Student, 2007
My research interests include visualizing frog leg muscle-tendon interaction like the medieval ballista and joint gearing like a winched catapult. At the ankle, the Cuban tree frog utilizes plantaris muscle power, an elastic Achilles tendon, and elongated lower limb lever arms to provide the joint torques necessary to power exceptional jumping performance. It is my objective to determine the muscle and ground reaction force moment arms and force ratios - the effective mechanical advantage (EMA) - of the Cuban tree frog ankle extensor muscle. I use inverse dynamics based on force plate, 3D kinematics, high-speed video analysis, and ankle extensor isolated muscle force experiments to determine how EMA as well as the magnitude of time-integrated muscle force change throughout jump accelerations.

Kevin Mazurek, ScB Bioelectrical Engineering, 2008
I am currently studying the compliance of muscles in the bullfrog by conducting an experiment that stimulates the gastrocnemius (plantaris) while keeping the knee and ankle locked. From this I can measure how much the muscle contracts against the tendon. I am also helping in an experiment that compares the force and power output of the gastrocnemius in running turkeys during steady speeds and accelerations.

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