Copyright theconversation
Once seen only on the feet of elite runners at the Olympics and other premier running events, the so-called “super shoe” has moved from racing podiums to pavements. Today, you’re just about as likely to spot them at a Saturday Parkrun as you are on the world stage. So what are they exactly, how do they work and do they potentially increase injury risk? What are ‘super shoes’? In 2016 at the Rio Oympics, Eliud Kipchoge – the only human to run a sub two-hour marathon – used the prototype of the Nike Vaporfly. This shoe was lighter than normal running shoes and embedded with a rigid, curved plate and a new type of foam. Many sportswear brands have since developed their own version of a super shoe, now heavily marketed to recreational runners chasing the tantalising promise of a personal best, albeit at a high purchase cost (often costing A$100 more than regular running sneakers). But how different is the super shoe from a traditional sneaker? The composition of a super shoe typically combines three key features: a carbon-fibre plate to propel the foot forward layers of specialised foam that compress and rebound more than traditional sneakers a curved “rocker” design to encourage a more efficient transition into each stride. This technology has sparked controversy, with critics and governing bodies questioning whether the technology blurs the line between athletic ability and unfair advantage. Should recreational runners be using super shoes? Super shoes were originally designed to maximise elite performance and have been shown to improve running economy by 2.7%, which can translate into faster race times. This finding was based on an independent review of ten super shoe studies – some of which were funded by shoe companies. However, some of the key materials used in super shoes have limited durability, which may require users to buy replacements more often. Exactly how much more often is not currently known. Read more: How do I know when it's time to replace my running shoes? While super shoes are now marketed to recreational runners, research indicates the benefits are greatest for highly trained runners and when running at fast speeds. However, performance benefits aren’t the only consideration. Now, researchers are beginning to question whether the very features that are meant to boost performance may actually increase the risk of running-related injuries. Will they increase injury risk? Early reports of runners developing midfoot stress fractures after switching to super shoes have sparked safety concerns in the running community. Although the exact mechanisms of these injuries aren’t yet clear, they likely relate to a mismatch between the loads that bones, muscles and tendons are used to and the altered loading caused by the new shoes. Carbon fibre plates make super shoes stiffer and harder to bend. This restricts foot movement, which in turn increases loading in the midfoot region and in the long foot bones (metatarsals) – common sites of running-related bone injury. Additionally, the thicker midsoles in super shoes may allow more downward movement of the midfoot bones, adding to the stress experienced at this location. However, the opposite impact on bone loading occurs at the shin (tibia), where super shoes can reduce tibial load accumulation during prolonged running. How can they be integrated into running training? Experts typically recommend reserving super shoes for race days or key training sessions. More research is needed to understand their long-term effects. As a result, any decision to use super shoes for training should be carefully considered and planned. Independent research has found some runners feel super shoes are easier to run in, which may encourage more frequent and intense training. But a sudden spike in weekly running could increase the risk of a training load-related injury — particularly given the increased foot bone loading associated with super shoes. However if runners limit their super shoe use during training and give their bodies time to adapt to the altered loading patterns, faster speeds and greater distances, there could be advantages. Early research results from recent international conferences reflect a mixed injury risk picture: a United States study found runners training for a half-marathon in super shoes were about half as likely to get injured compared to those in traditional shoes, while a Swedish study tracking runners for nine months found no difference in injury rates. Neither of these research groups disclosed their funding sources in their published reports, so the involvement of shoe companies is unknown. Tips for people considering super shoes Although the evidence is still evolving, there are some practical steps runners can consider if they decide to use super shoes: health vs performance: super shoes may assist your race day goals. However, they are expensive, may degrade more quickly than traditional running shoes, and are probably unnecessary if you are running solely for health benefits slow, gradual introduction: if you need the performance boost from super shoes, then ensure you give your body time to adapt to them during training runs they’re not for everyday use: the impacts of prolonged super shoe use are unknown. Use them selectively until further guidance is available know your bone health: if you have a history of foot stress fractures, then be very hesitant to use super shoes given the potentially increased risk of midfoot stress fracture careful monitoring: if you’re trying super shoes and feel discomfort, it could be a warning sign of injury problems. Switch back to shoes that don’t cause you any problems if you experience pain or discomfort, and seek medical advice.
