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A study by former grad student Sam Morton may help put to rest the “muscle-bound myth”concerning strength training, observes UND faculty member Jim Whitehead.

A former grad student’s research challenges myths about exercise.

The widespread belief that strength training makes people “muscle-bound” and inflexible might be on its way to urban legend status because of a study conducted at UND.

“Resistance Training vs. Static Stretching: Effects on Flexibility and Strength” has been accepted for publication in an upcoming issue of the Journal of Strength and Conditioning Research.  The article is based on the master’s thesis in kinesiology by former UND graduate student Sam Morton, now the wellness director at the Missouri Valley Family YMCA in Bismarck, N.D.

“Lots of people have done full-range resistance training and gotten more flexible, not less, but nobody had put it to the test,” said Jim Whitehead, associate professor of physical education, exercise science and wellness.  “I’d been trying to get a student interested in that topic for a long time.  Sam finally came along and was very interested.  He took it on and did a fine job.”

Morton’s study compared three groups of people over a five-week period.  One group engaged in resistance training only, another conducted static stretching only, and a third control group was inactive.

“Nobody’s (study) had one group doing stretching and no strengthening, and another group doing strengthening and no separate stretching,” Whitehead noted.  “It’s the first study of its kind, so far as we can tell.  We’ve searched and searched, and can’t find anybody else having done it.”

The results showed that there was little difference in flexibility between the resistance training and static stretching groups, but both were superior to the control group.

“Flexibility isn’t hindered through resistance training,” Morton said.  “We saw that it was improved and, to some extent, improved to beyond what static stretching could do.”

Whitehead presented the research results last year during the American College of Sports Medicine’s 57th annual meeting in Baltimore.  Out of thousands of presentations, it was one the organization chose to highlight.  WebMD, a Swedish fitness magazine and numerous health- and fitness-oriented Web sites published articles on the UND study.  It’s understandable why the study made a splash.

“If you go back 40 or 50 years in the early days of physical conditioning, the mythology that grew up around strength training was that if you got bigger muscles, they would impede your flexibility,” Whitehead said.  “The standard cliché was that you better stretch what you strengthen.  Based on my own experience and observations, I had always thought if you’re doing full-range strength training, you’re unlikely to have a flexibility problem.”

Whitehead stressed that the study results should be considered preliminary and that more research conducted on larger groups over a longer period of time is needed.

“There’s going to be quite a bit of research spawned by Sam’s paper,” he said.  “I suspect there will be more specific studies looking at how much flexibility you need for athletes, for older folks maintaining everyday function, and for people interested in maintaining general fitness.  There will be many areas for future follow-up.”

Morton already incorporates what he learned from his study into his training programs at the YMCA in Bismarck.

“I have started an athletic development program here where I use the results of my research every day,” he said.  “It’s among the things that I preach to everybody who comes in here.”

Regardless of whether additional research on the subject is conducted at UND or elsewhere, Whitehead expects that Morton’s study will have a lasting impact on exercise science.

“We were trying to expand present knowledge,” he said.  “The important thing is to find out what’s true, not what we want to be true.  I think what we found is going to hold up reasonably well.  The data will be the judge of that.”

Patrick C. Miller | Staff Writer