Complex sentence: With a personal best, in a time of 49.38, he finished 22nd in the heats he qualified to the semi finals where he finished 19th in a time of 49.54.
Split into simpler sentences: With a personal best, in a time of 49.38, he finished 22nd in the heats. He was qualified for the semi finals where he finished 19th in a time of 49.54.