Good running shoes do not always come with a premium price tag, according to a study.
The study, by Hong Kong Polytechnic University and Harvard Medical School, found that shoes that simulate barefoot running increase leg and foot muscles, which helps to reduce running injuries. Even white plimsolls - which are often available under HK$100 - serve the purpose.
PolyU rehabilitation sciences department assistant professor Roy Cheung Tsz-hei said there is no clear cut line between traditional running shoes and minimalist shoes, but described certain characteristics of the latter - no or little difference in thickness of sole between heel and toe, no arch support, high flexibility, light and with a thin sole.
Cheung yesterday released a study his university and Harvard Medical School conducted in 2013 and published this year.
The team recruited 38 recreational runners - 21 men and 17 women of an average age of 35 and at least six years of experience - who had never tried minimalist shoes.
They were put into two groups: a control group training with traditional running shoes and a experimental group with minimalist shoes. Both groups were first given a magnetic resonance imaging scan to measure their right leg and foot muscles. Then they started a six-month transitioning program, starting with walking and jogging before gradually returning to their previous training intensity.
Another MRI scan was conducted after the training. It showed the experimental group gained more leg and foot muscles, while the control group was unchanged.
The mean volume of the experimental group's extrinsic foot muscles attached from the leg to the foot rose 7.05 percent and the intrinsic foot muscles attached from the heel to toes up by 8.8 percent.
Wylie Tsang, a participant, described her experience: "My leg muscles were very sore at the beginning."
But she said the unpleasant feeling went away a couple of months later and she felt her muscles became stronger, the calves especially. "I joined the experiment in mid 2013 and I got hurt twice in the previous year. So far I haven't got new injuries."
Cheung explained that the minimalist shoes provide minimal cushioning and no mechanical support to the foot arches and therefore require greater demands for strength, and runners also experience higher strain and greater force generation in the posterior and medial calf muscles.Runners tend to land with their heels with traditional shoes, and the forefoot with minimalist shoes. Cheung said mid or forefoot landing imposes more stimuli to the anterior part of the foot and therefore strengthens the muscles responsible.
Stronger muscles and different landing help to avoid common running injuries such as plantar fasciitis, which results in pain in the heel and the bottom of the foot.
Asked about the benefits of running shoes developed over the past 15 years, he said their effectiveness in reducing injuries is limited as reflected by the high percentage of injuries mentioned in the study.
Runners who switch shoes should allow preferably six months of transitioning as a sudden change can cause bad foot injuries.