Complex sentence: On the other hand, most member federations have more relaxed rules for their national records, which means many more opportunities for record-breaking, especially so in the non-Olympic events, where World Cups are not held.
Split into simpler sentences: On the other hand, most member federations have more relaxed rules for their national records. This creates many more opportunities for record-breaking, especially so in the non-Olympic events, where World Cups are not held.