Table 1 Key phrases for mechanical group comments

Stiffness

The following are “key phrases” in the responses that corresponded with this surface property:

“Too hard”, “hard impact”, “unforgiving surface”, “pounds on joints”, “no give in ground” , “tougher surface”, “firm surface”, “poor shock absorption”

Friction

The following are “key phrases” in the responses that corresponded with this surface property:

“Studs/foot get stuck”, “no give” , “feet stick”, “cleats don’t slide”, cleats get caught”

Metabolic cost

The following are “key phrases” in the responses that corresponded with this surface property:

“Requires more physical effort”, “running in sand”, “work harder”, “heavy surface”, “body gets tired faster”, “fatigues body“