According to Farrington (2012), this athlete was twice periodonikes in stadion and hoplites. He was probably active somewhere between 150 and 175. His first Olympian victory, which Pausanias mentions (10.34.5), was probably in 161. Pausanias also mentions that Mnasiboulos was killed during an invasion of the Costoboci, a Dacian tribe, around c. 170-175. - YP
The inscription IG IX.1, 146 mentions that he was twice periodonikes, but does not mention the disciplines. Pausanias only mentions that he won in both the stadion and hoplites at the Olympic games - PS
Mnasiboulos died while leading a group of citizens to defend from attacking Kostoboki, a Dacian tribe. In Elateia, a bronze statue of him is erected on the 'street of the runner' (τὴν ὁδὸν τοῦ δρομεως) (Gouw).