Running shoes with a higher heel may raise the risk of injury by changing how the feet strike the ground. In a small study, researchers found that running shoes with heels around 20 millimetres high may be more likely to cause discomfort and tightness in the lower legs than those with little or no heel. However, other aspects of running shoes could also affect injury risk.
When running, the ankle rotates backwards, forwards and sideways as the foot hits the ground. This helps to keep the runner stable, while generating a force that propels them forwards.
Researchers have previously found that the shoes used for running influence how the ankles and feet flex. The heel height of these shoes typically ranges from just 1 or 2 millimetres to around 40 millimetres, but it is unclear how these height differences affect ankle and foot movement.
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To find out, and at Harvard University recruited eight people to run on a treadmill for 30 seconds while they wore what the researchers described as 鈥渕inimal鈥� shoes, made from a rigid material with a 6-millimetre-high sole running along the base.
The participants also ran while wearing minimal shoes with the same sole height and a 6 millimetre heel, followed by a 20 millimetre heel.
By analysing video recordings of the runners, who were asked to strike the ground with their heels first, the researchers measured how their feet and ankles moved immediately after their heels hit the floor.
The researchers found that a higher heel height increased the speed of the participants鈥� so-called plantar flexion movement, defined as the movement of the foot in a downward direction, like when standing on your toes. This may overuse the tibialis anterior muscle in the lower leg and its tendons, which could lead to discomfort or tightness, according to the pair.
An increased speed of plantar flexion movement could result in a greater strain on the lower leg muscles as they try to counteract this acceleration, raising the risk of injury, says at the University of South Florida.
However, it is unclear whether the participants naturally ran heel first or if some would usually hit the ground with the balls of their feet, says Davis. If the latter, the results may not reflect how higher heels could influence their ankle movements if they ran as normal, she says.
Heel height is also only one factor of running shoes that influences ankle movement, with others including the shoes鈥� materials and the shape of their heels, says Davis.
bioRxiv
