Trainers versus bare feet

“Running barefoot may be better for joints than trainers,” The Daily Telegraph reported. It said a study has claimed that running shoes put more strain on the joints than wearing heels.

This small experimental study found greater joint torsion (twisting) when it compared running in trainers on a treadmill to running barefoot. However, only one type of running shoe was tested on one occasion, and the runners were not specially fitted for their shoes. It also isn’t clear whether the differences would persist with longer-term use, or increase the risk of joint injury. Finally, different types of shoe were not compared, so the newspaper’s suggestion that running shoes put more strain on the joints than high heels is unsubstantiated.

More research in different shoe designs, in different environments and in different populations is needed. At present, runners of all levels of fitness are advised to continue to train wearing the right fit of running shoes.

Where did the story come from?

The research was carried out by Dr D Casey Kerrigan and colleagues from the Universities of Colorado and Virginia, and published in the Journal of Physical Medicine and Rehabilitation . The research was supported by grants from several sports footwear technology companies.

The news stories have generally reported this piece of research accurately, but have not highlighted its many limitations. In particular, the headline that “high heels trounce trainers as study looks at impact on joints” is misleading, as this study did not examine high heel use at all.

What kind of research was this?

This was an experimental study designed to investigate the effect of running shoes or trainers on the joints of the leg while running. The study was carried out in two phases in a motion laboratory.

This was a small experimental study and so only limited conclusions can be made. These assessments were made on only one occasion in a laboratory setting. It is unknown whether similar findings would be obtained outdoors, if they would persist with longer-term use or if the risks of joint injury or arthritis are increased in the long term.

A more reliable study for this particular question would be a randomised design in which people were assigned to either barefoot or running shoe use, and assessed on numerous occasions and with longer follow-up. Further studies could consider different types of running shoes under various conditions and in different populations. No comparison can be made to different styles of shoe, such as high heels, as the Daily Mail suggests, because different shoes were not directly compared.

What did the research involve?

The researchers enrolled 68 healthy young adult runners - 34 men and 34 women - who typically ran a minimum of 15 miles per week and were free of any musculoskeletal disease or injury. A standard running shoe (Brooks Adrenaline) was compared with running barefoot in each participant while they ran on a treadmill at a speed they had chosen as their normal pace.

The researchers captured the three-dimensional motion of the run using reflective markers placed at various joint sites including the hip, knee and ankle. The treadmill also collected ground reaction force data. A model was used to take into account both measures and calculate the maximum three-dimensional external joint torsion (twisting) at the hip, knee and ankle. Joint torsion was compared between running barefoot and running in trainers.

What were the basic results?

Compared with running barefoot, running in trainers increased joint torsion at the hip, knee and ankle. The greatest joint torsion effects seen with the trainers compared to barefoot running involved a 54% increase in internal rotation at the hip, 36% increased torsion while flexing the knee and 38% increase in varus torsion at the knee (causing the legs to bend inwards towards each other).

How did the researchers interpret the results?

The researchers concluded that their findings of the flexion and varus torsion at the knee suggest that greater pressure was occurring in the patellofemoral and medial compartments of the knee, which are more prone to osteoarthritis.

Conclusion

Though this study has found greater joint torsion when a person runs in trainers on a treadmill compared to running barefoot, it has numerous limitations. Taken together these indicate that further research is needed before any firm conclusions can be made. This study does not provide enough evidence to suggest that running barefoot is better for the joints than running in running shoes. Also, there could be other stresses placed on the body without the use of running shoes that may outweigh the stresses identified here.

• This was a small population of healthy young people who typically run more than 15 miles a week. Therefore, they are seasoned runners and not a typical sample of the average population.
• Assessments were made on only one occasion in a laboratory setting and it is not known whether the effects observed would differ with outdoor use, would persist with longer-term use or would increase the risk of joint injury or arthritis in the long term.
• A standard running shoe was used in this experiment. It wasn’t a personalised shoe or one necessarily appropriate for the individual’s running style.
• More research is needed to assess other running shoe designs than the single brand tested here, and for different types of usage, for example walking, jogging or sports.
• No comparison can be made to different types of shoes, for example to high heels as the Daily Mail suggests, as different shoes were not directly tested.
• As the researchers say, the technique of three-dimensional gait analysis in general has limitations in assessing joint effects.
• There may be subtle differences in the way a person runs barefoot compared to how they run in trainers. As the researchers found, although the runner kept the same speed both times, their stride width was less when running barefoot. There may be other modifications to their running style that the person made that were not observed and that may be responsible for the reduction in joint twisting.

Although this was a small experimental study and few firm conclusions can be made, the results highlight the stresses the body is subject to while doing high-intensity, high-impact sports. These stresses can be alleviated or reduced with appropriate warm-up and cool-down sessions, sensible running durations, use of the correct footwear, by taking into account the running surface and ensuring that rest periods are taken.