What makes a cross trainer?
A technical running shoe is designed to run in a relatively straight line on a
relatively flat surface, which has a reduced need for stability in the upper. We see the introduction of the upper being all mesh or knitted fabrics
A tennis shoe is designed to cope with stop/start & sudden change in
directions. This requires a lot more strength in the upper, which until recent times were predominantly leather.
The integrity of cross trainers was primarily in the upper. Early models were
mid cut (a low cut boot) offering ankle support. Uppers were predominantly leather. In recent years a blend of leather & mesh with reinforcing has reduced the weight without compromise. It is interesting that some models continue with an all leather upper option.
Whilst the major difference is in the upper there were elements within the
midsole & outsole that also added to the integrity of the cross trainer. Foot framing is little flange like extensions of the midsole onto the upper. Cup soling is extensions of the outsole across the midsole up to the upper. These features are seen to improve the mediolateral stability of the shoe.