Running shoes have become increasingly cushioned over the years in an effort to reduce impact and help protect against leg injuries such as runner's knee (patellofemoral pain syndrome), stress fractures, shin splints, and muscle or joint injuries.
However, running injuries have not decreased and new research suggests that highly cushioned trainers may actually increase the risk of injury.
Dr Juha-Pekka Kulmala and colleagues examined impact loading and the spring-like mechanics of the legs in 12 men when running in two styles of trainer used for running: a conventional control running shoe and a highly cushioned 'maximalist' shoe.
They found that highly cushioned trainers change the spring-like mechanics of running, and amplify rather than attenuate impact loading. In other words, the legs experience a greater impact with every stride.
This effect was more pronounced at a fast running speed (14.5?km/h), where ground reaction force impact peak and loading rate were 10.7% and 12.3% greater, respectively, in the maximalist shoe compared to the conventional shoe, whereas only a slightly higher impact peak (6.4%) was found at a slower speed (10?km/h).
The researchers attributed the greater impact loading with maximalist shoes to the legs being stiffer during landing compared to when running with the conventional shoes.
However, the findings, published in the journal Scientific Reports, don't suggest that runners should wear shoes with no padding at all.
Dr Kade Paterson, a podiatrist at the University of Melbourne, told the New Scientist: "As a sports podiatrist, I've seen patients who've reported improvements with maximalist running shoes and others who've got injured in them so there probably isn't a one-size-fits-all approach."
"Like many health-related things, we should be somewhere in the middle," he concluded.