Synthetic surfaces, popularly called Astroturf since the Houston Astrodome made it famous, were introduced in the 1960s to reduce strain on the playing surface and thus reduce field maintenance.

But it was linked to an increase in injuries, one example in football parlance being "turf toe". 

Third generation artificial surfaces behave more like grass and soil but continue to be associated with injuries to the foot, ankle, toe, knee and even concussions. Characteristics of the play surface directly affect how much energy is absorbed by the athlete upon impact and that means shoes are important.

A new paper says the key to minimizing injuries on natural and artificial playing fields may be to understand the interplay between different types of athletic shoes, specific sports and field surfaces.

 Determining the shoe-playing surface interface is complex and challenging as it is influenced by human factors (i.e., the athlete's body weight, velocity and acceleration, deceleration, loading rate, and angle of the foot and height before contact), shoe factors (i.e., sole type and cleat/stud material of footwear, and number and size of cleats and cleat configuration), type of playing surface, and related environmental factors.

"Optimal shoe-playing surface conditions may be level and sport-specific," said orthopaedic surgeon and lead study author Mark C. Drakos, MD. "The shoe-playing surface interface is a modifiable risk factor for injury, and further research is needed to improve playing conditions for athletes of all levels."

Highlights:

• Most types of shoes have higher peak torque (foot movement and movement force) on artificial turf than on natural turf.

• Sole material and cleat pattern and shape may affect torque. For example, shoes with small cleats place the lowest amount of pressure on the foot, and may potentially minimize the incidence of foot stress fractures on artificial surfaces.

• Because of constant changes in both the athletic shoe market and artificial surfaces, much of the existing research on the shoe-playing surface is outdated.

"The role of the shoe surface interface in the development of lower extremity injuries continues to be clarified," said Drakos. Optimal shoe-playing surfaces are most likely level- and sport-specific. The shoe-playing surface interface is a modifiable risk factor for injury and further research is needed to improve playing conditions for all athletes.

 Published in the Journal of the American Academy of Orthopaedic Surgeons