Complex sentence: On his return to international competition his times were significantly worse than he achieved prior to drug use: in the 100 m final at the 2006 European Championships, Chambers ran a sub-par 10.24 s and finished in fifth place.
Split into simpler sentences: On his return to international competition, drug free, his times were significantly worse than he achieved prior to drug use. In the 100 m final at the 2006 European Championships, Chambers ran 10.24 s and finished in fifth place.