From pros and trecho (including its alternate); to run towards, i.e. Hasten to meet or join -- run (thither to, to).
see GREEK pros
see GREEK trecho
STRONGS NT 4370: προστρέχωπροστρέχω; 2 aorist active participle προσδραμών; to run to: Mark 9:15; Mark 10:17; Acts 8:30. (From Aristophanes and Xenophon down; for רוּץ in Genesis 18:2, etc.)