Traditional Vishpala (viśpálā) is a woman (alternatively, a horse) mentioned in the Rigveda (RV 1.112.10, 116.15, 117.11, 118.8 and RV 10.39.8).
Vishpala is helped in battle (alternative, in the prize-race) by the Ashvins.
As she lost her leg "in the time of night, in Khela's battle" (alternatively, "in Khela's race, eager for a decision"), they gave her a "leg of iron" so that she could keep running (1.116.15).
The interpretation as a female warrior in battle is due to Griffith (in keeping with Sayana), the interpretation as a horse race is due to Karl Friedrich Geldner.
As is often the case in the Rigveda, especially in the young books 1 and 10 (dated to roughly 1200 BC) a myth is only alluded to, the poet taking for granted his audience's being familiar with it, and beyond the fact that the Ashvins gave Vishpala a new leg, no information has survived, neither about Vishpala herself nor about "Khela's battle", or indeed the character of Khela (the name meaning "shaking, trembling").