The Ohio State University

Abstract:

The structure of the foot and ankle has the potential to influence the speed of locomotion.  The moment arms of muscles, for example, directly dictate the magnitudes of the moments muscles produce for a given force, but also have the potential to influence muscle force generation by determining sarcomere shortening velocity for a given movement.  Previous examinations of the joints of humans and animals suggest that skeletal structure is determinative of speed, but in complex ways that also depend upon muscle architecture.  We investigated how musculoskeletal structure influences locomotor ability in two very different populations: collegiate sprinters and elderly adults.  For each, we measured Achilles' tendon lever arms using an ultrasound-based assessment of tendon excursion.  Sprinters were shown to have smaller ankle plantarflexion moment arms than height-matched young non-sprinters.  A positive correlation was found between the free walking speed of healthy elderly adults and their plantarflexion moment arms.  These results suggest that sprinting ability in young subjects is enhanced by small plantarflexion lever arms, but that the opposite is true for walking ability in older adults.  To explain this contradiction, a simple mathematical model was developed to simulate a sprinter's push-off during the first steps after the start in order to elucidate the benefits of small muscle moment arms for producing propulsive impulse during rapid plantarflexion.

Bio:

Dr. Stephen Piazza received his undergraduate degree from Harvard University, followed by graduate degrees in mechanical engineering from Northwestern University.  Since 1998 he has been in the Department of Kinesiology at Penn State University, where he also holds appointments in Mechanical Engineering and Orthopaedics & Rehabilitation.  His research interests include the mechanics of locomotion, joint mechanics, computer simulation of movement, and motion analysis methods.  He was the recipient of a CAREER award from the National Science Foundation, and has received funding for his research from the Whitaker Foundation, and from industry.  Dr. Piazza holds Associate Editor positions with the Journal of Applied Biomechanics and Foot & Ankle International, and currently serves as Past-President of the Gait and Clinical Movement Analysis Society.

Hosted by: Professor Robert Siston, 247-2721, siston.1@osu.edu

For information on ME 888 seminars contact Professor Walter Lempert at 292-2736 or lempert.1@osu.edu.

The seminar will be held in E001 Scott Laboratory.