As the shoe ages , the foam compresses .
As the shoe ages , the foam does n't decompress as quickly , meaning the average runner who works out for an hour , four times a week , would need to get new shoes in about seven months .
As the shoe ages , the foam compresses , but does n't decompress as quickly , meaning the average runner who works out for an hour , four times a week , would need to get new shoes in about seven months .