Laird Harrison

June 04, 2015

SAN DIEGO — Highly padded maximalist shoes could increase the risk of running injury, contrary to manufacturers' claims, researchers say.

"Cushioning lulls you into thinking you can slam your foot down," said coauthor Irene Davis, PhD, director of the Spaulding National Running Center at Harvard University in Cambridge, Massachusetts.

Her coauthor, Matthew Ruder, MS, also from the Spaulding National Running Center, presented the finding here at the American College of Sports Medicine 62nd Annual Meeting.

About a decade ago, work by Dr Davis and some of her Harvard colleagues helped fuel the popularity of minimalist shoes and barefoot running. But many runners injured themselves after making the switch from conventional footwear.

"It's really put a bad spin on the minimalist shoe movement," Dr Davis told Medscape Medical News. She argues that injuries would be low if runners made a slow, careful transition to minimalism.

Cushioning lulls you into thinking you can slam your foot down.

Instead, not only have many runners returned to conventional shoes with thick heels, some are buying maximalist shoes that feature thick soles and thick heels, which manufacturers claim attenuate the impact of running.

To evaluate these claims, the investigators recruited 14 male runners who ran at least 10 miles per week. Their average age was 31.6 years.

The team collected data on an instrumented treadmill at a standard speed of 2.68 m/s.

The runners alternated between maximalist and traditional running shoes. After letting the runners get used to the new shoes for 3 minutes, the researchers measured a variety of ground reaction forces.

Force values were normalized to body weight. Vertical impact loading was significantly greater with the maximalist shoes than with the traditional ones. Previous studies have established a correlation between vertical impact loading and injuries, Ruder explained.

Table. Ground Reaction Forces

Force Maximalist Shoe Traditional Shoe Difference
Vertical impact peak, body weight 1.52 1.52 0.00
Vertical instantaneous loading rate, body weight/s 63.97 62.00 1.97
Vertical average loading rate, body weight/s 55.68 46.62 9.06
Peak lateral force, body weight 0.07 0.08 –0.01
Peak medial force, body weight –0.13 –0.13 0.0
Peak vertical force, body weight 2.48 2.50 –0.02


Measurements of peak medial, braking, propulsion, and vertical impact peak were similar between the two types of shoes, as were foot angle and cadence.

The investigators would like to compare runners who already have the habit of running with the maximalist shoes, Ruder told Medscape Medical News.

In addition, they are now using accelerometers to measure kinetics at the tibia with the maximalist shoes.

Although the data so far don't look promising for maximalist shoes, it is possible that some people might benefit from them, said session moderator Clare Milner, PhD, from Drexel University in Philadelphia.

"In a lot of cases, you want to look at what's good for the individual," she said. "It's probably not one-size-fits-all."

Dr Davis, Mr Ruder, and Dr Milner have disclosed no relevant financial relationships.

American College of Sports Medicine (ACSM) 62nd Annual Meeting: Abstract 1160. Presented May 28, 2015.


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