E-commerce sales of athletic footwear in the US hit an estimated US$5bn in the year to April, up 21% on the year before, according to figures released by research business NPD Group.

The surge meant that e-commerce sales accounted for 18% of the total market, which rose 5% over the same period to $28bn.

“Online offers the ability to find the product you want at the best value, but online also offers the widest assortment of athletic footwear where brick-and-mortar has limited space,” said Marshal Cohen, chief industry analyst at NPD Group.

“Consumers are clearly looking for this bigger online assortment each year and some retailers are working really hard at maximising space to include as many style offerings as possible.”

Some 37% of online athletic footwear purchases are intended for sports use, the research said, a higher proportion than the 30% share of in-store purchases.

“Those who shop online care more about style, price, and brand, while consumers who shop in store focus more on comfort, caring less about the style and brand,” said Cohen.

“Surprisingly, men are more superficial about the athletic footwear they buy than women.”