Jul 18, 2011 - Claremont, CA -

How humans use their leg muscles when they walk is as varied as the human body itself - and is a rich subject for research this summer by a team of HMC undergraduates in the lab of biology professor Anna Ahn.

The summer research project focuses on the neural control and mechanics of human locomotion, a field that has implications for areas such as prosthetics, robotics, and developing footwear. Taking a multi-disciplinary, integrative approach, they examine the different levels of organization that influence the behavioral output of the neuro-musculo-skeletal system in humans while they walk.

The students use state-of-the-art equipment to collect and analyze data on human subjects walking at various speeds. They record 3-D joint positions with a high-speed motion-capture system. They use ultrasonography to measure muscle thickness and muscle fiber angles. Electromyography (EMG) sensors capture electrical activity in the muscle. Finally, they developed a foot pressure measurement system to determine how weight is distributed during walking.

"We're recording four vastly different types of data all at once," said Christian Stevens '14. "It's a pretty spectacular opportunity to work with the amount of stuff we have."

"A lot of people have studied every part of this separately, but no one has really put it together," explained Teri Cinco '13, a biology major. "I think the way that we composite all the information we record, to do something useful with it, is really cool."

Professor Ahn's research has demonstrated that humans use two different motor recruitment strategies while walking: either they use their inner calf muscles more strongly, termed medial gastrocnemius biased, or they use the two calf muscles equally, termed unbiased. The students run experiments to examine the biomechanical differences between people who use these two different motor control strategies.

Poised in front of an EMG monitor showing a subject whose outer calf muscle was firing equally with the inner, Parker Martin '13, an engineering major, said what he enjoys most is examining the measurements. "I really like to code, and the analyzing of this data. It's fascinating to me to watch a person's muscle data as it progresses from their brain telling their calves to contract to a voltage waveform and eventually into graphs from which we can learn and see patterns."

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More than 170 Harvey Mudd College students are pursuing summer research projects alongside 45 faculty members in biology, chemistry, computer science, engineering, mathematics and physics.

The projects are part of Harvey Mudd College's Summer Research Program, which engages students in 10 weeks of full-time research.