Apparently you never smell your own, the sense of smell adapts quickly so you won’t smell it after the first couple of minutes, but once you leave the area you readjust and on returning it hits you with a bang. Luckily for me, smells that your nose encounters regularly aren’t as obnoxious. Most people think that their own doesn’t stink. But it’s all an illusion; we simply become accustomed and desensitised to things that are familiar. The brain actually adapts to bad smells, if it didn’t, it would be overloaded by the constant sensory input. However the reaction to scent varies. In fact the sense of smell may to be linked to personality traits – people who are more uptight are more sensitive to bad smells (Seo et al., 2013) Unfortunately for my wife women consistently out-perform men on all tests of smelling ability (Sergeant, 2010; Novakova et al., 2013). But I love my old running shoes and I’m keeping them no matter how badly they smell!
The sense of smell activates two areas of the brain that are strongly concerned to emotion and memory. This may be why smell, more than any other sense, is so successful at triggering emotions and memories (Herz et al., 2004). I have memories associated with runners, the miles logged, thoughts had, problems I have worked through, people I have met. Bad runs in a particular pair of runners get stored as learning experience – beta testing, and good runs get stored as aspirations for the future. It’s the weirdest relationship I have ever had, maybe it’s because they smell so badly!! But I never throw them out. Shoe companies recommend that running shoes should be replaced every 300-500 miles to avoid injury. The worry is that running shoes lose the ability to absorb shock (Cook et al., 1985). But many runners and joggers get endless mileage out of an old pair of runners with no apparent ill effect.
Yes the cushioning in runners does degrade. Following a rapid decrease initially, this deterioration tapers off and nearly levels out after 500 miles of running with runners retaining up to 80% of their initial cushioning. Even more interestingly there is no significant difference in the wear properties amongst many different brands. Nike shoes deteriorate just as much as the asics, adidas or brooks shoes (Cook et al., 1985). Despite the fact that the shoes lose 20% of their cushioning capacity, there was no change in impact forces…. yes none (Rethnam & Makwana, 2011). So why do I still buy so many runners? I’m fascinated by the potential for improvement in my running without doing more training (aren’t we all). Will this particular pair help me be better, be faster – I am an advertisers dream. I have minimalist runners, racing flats and neutral cushioned runners. If I take the minimalist runners – I have 3 pairs because they have been proven to make you significantly more economical than traditionally runners (Perl et al., 2012), I alternate these with neutral cushioned runners for comfort for my longer runs. Strangely, the risk of injury to the foot and ankle may actually be greater if running shoes are changed more frequently (Rethnam & Makwana, 2011). But I won’t stop buying new runners, the endless search for the best runner continues, I may never find it but I will enjoy the hunt and will continue to hide my old smelly runners from my wife …… I just hope I can remember where I hide them because you never smell your own!
Cook SD, Kester MA & Brunet ME. (1985). Shock absorption characteristics of running shoes. Am J Sports Med 13, 248-253.
Herz RS, Eliassen J, Beland S & Souza T. (2004). Neuroimaging evidence for the emotional potency of odor-evoked memory. Neuropsychologia 42, 371-378.
Novakova L, Varella Valentova J & Havlicek J. (2013). Olfactory performance is predicted by individual sex-atypicality, but not sexual orientation. PLoS One 8, e80234.
Perl DP, Daoud AI & Lieberman DE. (2012). Effects of footwear and strike type on running economy. Med Sci Sports Exerc 44, 1335-1343.
Rethnam U & Makwana N. (2011). Are old running shoes detrimental to your feet? A pedobarographic study. BMC Res Notes 4, 307.
Seo H-S, Lee S & Cho S. (2013). Relationships between personality traits and attitudes toward the sense of smell. Frontiers in Psychology 4, 901.
Sergeant MJ. (2010). Female perception of male body odor. Vitam Horm 83, 25-45.