Knit athletic shoes with continuous upper portion

A shoe, comprising:

• a sole defining a tread surface;
• a knit upper portion attached to the sole and defining a cavity, the knit upper portion comprising a cuff region surrounding an opening into the cavity and defining at least a portion of a perimeter of the opening, the cuff region comprising an elastic material;
• and
• a heel retainer positioned along an interior surface of the knit upper portion and protruding into the cavity, the heel retainer configured to conform to a wearer;
• wherein:
• the cuff region is configured to exert an elastic force that draws the heel retainer against the wearer to retain the shoe on the wearer;
• and
• the knit upper portion is knit as a single, unitary piece.

A shoe, comprising:

• an upper portion at least partially defining a cavity and comprising:
• a peripheral region extending around a perimeter of the upper portion and comprising a Eucalyptus fiber;
• and
• a flex region at least partially surrounded by the peripheral region and comprising the Eucalyptus fiber and an elastic material;
• a first set of eyelets positioned along an exterior surface of the upper portion on a first side of the flex region;
• and
• a second set of eyelets positioned along the exterior surface of the upper portion on a second side of the flex region opposite the first side;
• and
• a shoelace extending through one or more eyelets of the first set of eyelets and one or more eyelets of the second set of eyelets;
• wherein:
• the exterior surface of the upper portion is defined by a continuous knit textile;
• and
• the flex region, the shoelace, the first set of eyelets, and the second set of eyelets are configured to cooperate to tighten the shoe around a wearer's foot.