Runners who buy expensive training shoes in the belief that these are less likely to cause injury are deluding themselves, according to a study that appears on Thursday.
Researchers in Scotland tested running shoes, made by three manufacturers, that fell into three price bands -- low (40-45 pounds or 58-65 euros, 56.4-63 dollars); medium (60-65 pounds, or 87-94 euros, 84-91 dollars) and high (70-75 pounds, or 101.4-108.7 euros, 98.7-105.75 dollars).
After masking the manufacturer's logo and other tags with tape, the scientists slipped a thin pressure plate, shaped like an insole, into the shoes.
The device, called a Pedar, measured the pressure at three points on the sole of the foot: under the heel, across the forefoot and under the big toe.
The goal was to get an idea of the effectiveness of the cushioning that manufacturers add to the shoe to dampen the shockwave to the foot.
Thus, the higher the pressure, the greater the force that is transmitted to the runner when his or her foot makes contact with the ground.
They then asked 43 young male volunteers to put on the shoes and walk along a 20-metre (-yard) walkway in the lab. The volunteers each wore a small backpack which held a box that picked up data signals from the pressure gauge.
Nine volunteers then wore the shoes as they ran on a treadmill, to see if this made any difference in sole pressures as compared to walking.
"Plantar [sole] pressure was lower overall in low- and medium-cost shoes than in high-cost shoes," says their paper, which appears in the British Journal of Sports Medicine.
"This may suggest that less expensive running shoes not only provide as much protection from impact forces as expensive running shoes, but that in actual fact they may also provide more."
The volunteers were also asked to assess the masked shoes for comfort. But their preferences were subjective and bore no relation to the distribution of plantar pressure or the cost of the shoe, the investigators found.
Running is a high-impact activity. With every footfall, a middle-distance runner experiences an impact equal to 2.5 times his or her body weight -- and this force increases with speed and fatigue.
The impact transmits shock waves that are transmitted by the bones of the foot to the rest of the body, with the potential to cause knee damage, shin splints, muscle tears, Achilles tendonitis and other injuries.
Athletic footwear, though, can reduce the impact by a third through good cushioning, as compared to the impact from walking barefoot, according to the study headed by Rami Abboud of the Institute of Motion Analysis Research at Ninewells Hospital and Medical School, Dundee.
Abboud adds two small caveats. One is that the kinetics of running on the treadmill may have been different for the volunteers wearing the test shoes, when compared to wearing their own personal shoes.
The other was that the durability of the shoes' mid-soles and in-soles -- whether the "cushionability" of the footwear either faded or endured with prolonged use -- was not put to the test.