Shoe choice: weighty decisions

One of the prime functions of conventional running shoes is to provide sufficient cushioning to protect the limbs and joints such as the ankles and knees from the high impact forces, which are transmitted through the body with each foot strike. The minimalist running shoe philosophy on the other hand aims to provide a running experience close to that of barefoot running, while still offering the user some foot protection – albeit one that offers very little cushioning thanks to the thin soles in these shoes. Despite that, a number of recent studies on minimalist shoes have indicated that because they encourage more of forefoot strike pattern, they can actually result in less force being transmitted to the knees, which could reduce injury risk. But before you ditch your conventional shoes for minimalist alternatives, you might want to consider some research on the relationship between a runner’s bodyweight and the long-term risk of injury.

The research

The goal of the study was to compare the incidence of running-related pain and injury between minimalist and conventional shoes in trained runners [Am J Sports Med. 2017 Jan 1:363546516682497. doi: 10.1177/0363546516682497]. The researchers also wanted to investigate whether there was any relationship between the type of shoe worn, a runner’s body mass and the weekly training distance. To do this, 61 trained, habitual rearfoot striking runners who were running an average of 25km per week were randomly allocated to either minimalist or conventional shoes. Runners gradually increased the time spent running in their allocated shoes over a 26-week period. During this period, the runners recorded the degree of any running-related pain they suffered and also how long into the 26week period the first running-related injury occurred.

The findings

The first finding was that on average, greater pain was experienced with minimalist shoes, especially when the weekly training distance run was more than 35 kilometres per week. Eleven of 30 runners sustained an injury in conventional shoes compared with 16 of 31 runners in minimalist shoes. Another key finding was that when minimalist shoes were worn, the body mass of a runner was significantly linked to when he or she first sustained a running injury. The risk of sustaining an injury became slightly more likely for runners above 71.4kgs. Above 85.7kgs however, the risk was greatly increased. Overall, the researchers concluded that runners should limit weekly training distance in minimalist shoes to avoid running-related pain and also that heavier runners are at greater risk of injury when running in minimalist shoes.

Sports Performance Bulletin Verdict

Previous research has shown that minimalist shoes can result in less impact force and loading through the knee, even though they have very little cushioning compared to a conventional shoe. This is almost certainly because minimalist shoes encourage runners to adopt more of a mid or forefoot strike, rather than heel strike. A mid/forefoot strike can reduce knee loading by allowing the foot and calf muscles to gradually absorb some of the impact forces (as the heel lowers to the ground). However, what this new research shows is that when mileages creep up, any potential gains from minimalist shoe use may be lost. This seems to be particularly true for heavier runners, where even low mileages in minimalist shoes might result in increased risk of injury.

Practical suggestions

  • If you’re thinking about trying minimalist shoes, here are some useful tips:
  • Don’t make a sudden switch, which may lead to foot and calf muscle pain. Instead, start wearing minimalist shoes just during your warm up activities for at least six months to slowly strengthen your foot muscles;
  • After this period of adjustment, begin wearing minimalist shoes out on slow and low mileage runs;
  • Be aware that once your mileage in minimalist shoes rises above 20 miles per week, your injury risk may begin to increase.
  • Heavier runners (over 85kgs) should tread very warily (no pun intended) when introducing minimalist shoe use, and limit weekly mileage to under 12 miles per week.
  • If you suffer from persistent knee pain, seek the guidance of an experienced running coach or physiotherapist for a more in-depth look at your running gait and biomechanics.

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