title: Are old running shoes detrimental to your feet? A pedobarographic study.
abstract: BACKGROUND
  Footwear characteristics have been implicated in fatigue and foot pain. The recommended time for changing running shoes is every 500 miles. The aim of our study was to assess and compare plantar peak pressures and pressure time integrals in new and old running shoes.
  
  
  RESULTS
  This was a prospective study involving 11 healthy female volunteers with no previous foot and ankle problems. New running shoes were provided to the participants. Plantar pressures were measured using the Novel Pedar system while walking with new and participants' personal old running shoes. Plantar pressures were measured in nine areas of the feet. Demographic data, age of old running shoes, Body Mass Index (BMI), peak pressures and pressure-time integral were acquired. The right and left feet were selected at random and assessed separately. Statistical analysis was done using the paired t test to compare measurements between old and new running shoes.The mean peak pressures were higher in new running shoes (330.5 ± 79.6 kiloPascals kPa) when compared to used old running shoes (304 ± 58.1 kPa) (p = 0.01). The pressure-time integral was significantly higher in the new running shoes (110 ± 28.3 kPa s) compared to used old running shoes (100.7 ± 24.0 kPa s) (p = 0.01).
  
  
  CONCLUSIONS
  Plantar pressure measurements in general were higher in new running shoes. This could be due to the lack of flexibility in new running shoes. The risk of injury to the foot and ankle would appear to be higher if running shoes are changed frequently. We recommend breaking into new running shoes slowly using them for mild physical activity.
authors.affiliation: Department of Orthopaedics, Glan Clwyd Hospital, Rhyl, UK. ulfinr@yahoo.com.
authors.forename: Ulfin
authors.initials: U
authors.lastname: Rethnam
authors.forename: Nilesh
authors.initials: N
authors.lastname: Makwana