Byline: JEREMY MULLMAN

Nike has been touting its new cross-trainer line as "better than your better'' in ads, but its launch wound up worse than that of its barely promoted predecessor.

The footwear industry has hoped that dueling performance trainers from Nike and Under Armour would rejuvenate the long-declining cross-trainer segment, but Nike's performance-trainer sales actually declined in March, the first month Sparq shoes were on the market.

"The Nike results have been termed disappointing by retailers,'' said Matt Powell, an analyst at SportsOneSource who tracks the footwear industry. "They haven't moved the needle.''

The failure of Sparq-which stands ...