The Problem with Traction

  If you're a field sport athlete, think baseball, lacrosse, soccer and the like, then one of the issues for you is the proper footwear to use when playing your sport. You have to balance fit, comfort and function/performance and those factors can be impacted by the surface you play on whether it is turf or natural grass.
    There was a recent Phys Ed column in the NY Times by Gretchen Reynolds that addressed this very issue.
  Essentially, one has to balance the shoe's traction with the fact that too much traction esp. in rotational or cutting movements can be hazardous to your joints.
  A 2009 study on soccer players compared their traction amongst 3 versions of their soccer cleats: the regular length cleat, one where the cleats were 50% shorter and one where essentially there was no cleat...a flat in other words. The results showed that the longer, regular cleats offered the most traction but this study and other like it ignored the fact of how much is too much traction and thus more likely to lead to injury.
  There are essentially two types of traction a shoe can offer: linear traction (forward/backward) and rotational traction (lateral, cutting and rotational).  These factors are in turn impacted by the shoe's outsole material, whether it has cleats and what type, how many cleats and their arrangement, etc.
   A running robotic tester at the University of Calgary allows scientists to study how various shoes impact forward and rotational traction.
  The scientists there, led by John Wannop, studied hundreds of high school football players shoes for forward and rotational traction and then returned the shoes to the players. The trainers for each of the teams were asked to report any non-contact leg injuries throughout the season and the experiment was repeated for 2 more seasons. During this time the playing fields were switched from grass to artificial turf.
   Many players experienced non-contact leg injuries but the highest incidence of injury was amongst those athletes whose shoes had the most rotational traction while the athletes whose shoes had the best forward traction experienced the least injuries. It was previously thought that shoes that had the highest forward traction also had the highest rotational traction but evidently this is not the case. The bottom line is that shoes with good forward traction don't necessarily have good rotational traction and thus are safer as far as non-contact leg injuries are concerned.
  Interestingly, playing surface had little apparent impact on injury risk.
    The problem in the real world is getting this information as far as a shoe's forward vs. rotational traction values. Shoe companies don't provide this information and even if they could there are so many variables that go into such values that makes it almost meaningless: height, weight, movement patterns, speed, power as well as field conditions on any given day.
   But here are some general tips from Dr. Wannop on picking a good, safe shoe for you:

• Avoid models with multiple large, toothy cleats or rubbery nodules around the perimeter of the shoe as these tend to create too much rotational traction
• Look for shoes with groupings of smaller cleats in forefoot
• If you can try the shoes on and do some running and cutting in them. If they "stick" when cutting try another shoe

Train hard and train smart!

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