Kerrigan's Unique Research May Unlock Elder Gait Enigma

Aug. 1, 2007 -- D. Casey Kerrigan, M.D., professor and chair of the Department of Physical Medicine and Rehabilitation, may have discovered the “holy grail” of physical aging research.  Kerrigan’s novel analysis of the deterioration of gait—or walking—in older adults has attracted a major National Institutes of Health (NIH) grant.

With the rapid aging of our population, research into how to prevent the inevitable decline of physical health has become even more relevant.  Diminished walking ability among elders has a number of serious consequences, including loss of independence, reduced quality of life, and disability. 

Through exploratory studies in the Gait and Motion Analysis Laboratory, Kerrigan and her colleagues investigated the influence of age on gait.  “If we find a specific limiting factor, we can target it and prevent a downward spiral,” she explains.

Kerrigan discovered that elders had a reduced range of hip motion at faster walking speeds.  Specifically, she found that peak hip extension in older adults is 5 degrees less than it is in younger adults—a difference resulting from stiffness of the hip flexor muscles.  “The functional implication of this is that you need to have this full end range to walk properly,” says Kerrigan.  “If the range is limited, secondary problems such as short step length, postural changes, and back pain will develop.”

Kerrigan hypothesized that if older adults performed simple hip extension exercises geared towards increasing flexibility, their gait would improve.  Promising early results earned Kerrigan an NIH grant in 2006 of about $1.2 million to be used over a three-year period.

“This is the first NIH-funded study that looks at one component of exercise in a very scientific way,” notes Kerrigan.  Exercise programs for elders have typically focused on building strength in all muscle groups, but few have resulted in measurable improvements of gait.  Since this simple, targeted, hip exercise could have direct and quick benefits towards gait, Kerrigan may be on to something very significant.

Kerrigan is also intrigued by the promise of yoga in increasing hip flexibility.  She hopes to attract further grant funding to explore this connection.  A preliminary study has shown measurable biomechanical improvements.  And the small group of initial participants wants to continue doing yoga—which is a hugely important factor.  “The literature has shown that older adults are more compliant with yoga than any other exercise,” Kerrigan says.  “The problem with exercise programs is compliance.  People will be more compliant if they see a difference.”

Written by Melissa Maki, research communications coordinator for the Office of the Vice President for Research and Graduate Studies.