Distance runners have always known they need not look like super-muscular sprinters or body builders. Bulging muscles don't improve performance; they make you big and bulky when you want to be lean and mean.

Still, moderate strength training remains popular and recommended for distance runners because it can increase power and perhaps reduce injuries. Runners do a lot of quadriceps work in particular, hoping to diminish knee problems. Many runners have quadriceps muscles (on the top of the thigh) that are 30 to 40 percent stronger than their hamstrings (under the thigh).

This could be another example of too-much-muscle, according to a new study that compared the ratio of hamstring-to-quadriceps strength in highly-trained and recreational female distance runners. The highly-trained group had lower absolute muscle strength in both groups.

More importantly, the researchers say, the highly-trained runners had a ham-to-quad ratio of about 1:1 and significantly higher running economy than the recreational runners. Conclusion: “Running performance in long distance events may be related to greater hamstring muscle strength relative to quadriceps strength, and not to absolute muscle strength.”

The study has an intriguing backstory. Oyvind Heiberg Sundby, one of the coauthors, is a Norwegian mountain runner, physical therapist and exercise physiologist. He’s married to American Annie Bersagel, who recently won the Dusseldorf Marathon in 2:28:59. If she improves by several minutes in the next two years, she’ll have a shot at the U.S. Olympic team in 2016.

The study compared seven highly-trained women runners with 11 recreational women runners. The first group ran more than 60 miles a week, on average; the second, about 20 miles a week. Both had an average age in the mid 20s. All runners were tested for their running economy and the ratio of their hamstring-to-quadriceps muscle strength.

The less trained runners actually had stronger muscles. However, this correlated with lower running economy. The highly-trained runners had weaker muscles, but a more balanced ratio of ham-to-quad strength, and a significantly better running economy. That is, they used less oxygen at a given pace.

As Sundby explained to Runner’s World Newswire, the running stride forces both muscle groups to contract concentrically and eccentrically. The actions are opposite; while the quads are lengthening, the hamstrings are shortening; and vice versa. In a well-oiled machine, the two muscle groups appear to work together most efficiently when their strength is about the same.

Under “Practical Applications,” the paper notes: “As running is basically a series of horizontal jumps requiring a strong and highly efficient extensor apparatus, we suggest that runners should aim to include hamstring muscle strengthening exercises that imply horizontal motions.”

Sundby gave Newswire the following advice for runners: “Runners should do exercises that imitate running while they add some resistance or overspeed element. For example, steep hill bouncing or running, fast downhill running, or horizontal bouncing manuevers such as repeated single-leg long jumps. These exercises should be combined with more specific strength training that targets the hamstrings.”

The paper was coauthored by Mark Gorelick of San Francisco State University, and published in the Journal of Strength and Conditioning Research. It’s titled “Relationship Between Functional Hamstring: Quadriceps Ratios And Running Economy In Highly Trained And Recreational Female Runners.”

This content is created and maintained by a third party, and imported onto this page to help users provide their email addresses. You may be able to find more information about this and similar content at piano.io