Perhaps you should try some spelling variations:
"synchronised swimming" » "synchronized swimming", "synchronising swimming", "synchronised stemming"
"synchronize swimming" » "synchronize stemming"
"synchronism swimming" » "synchronism stemming"
"synchronizing swimming" » "synchronizing stemming"

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("synchronised swimming") or ((((("synchronize swimming") OR ("synchronism swimming"))) or ("synchronizing swimming"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("synchronised swimming") OR ((((("synchronize swimming") OR ("synchronism swimming"))) OR ("synchronizing swimming")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"synchronised swimming\") or (((((\"synchronize swimming\") OR (\"synchronism swimming\"))) or (\"synchronizing swimming\"))))".
• Removing quotes may allow a broader search: (( synchronised swimming ) or ((((( synchronize swimming ) OR ( synchronism swimming ))) or ( synchronizing swimming )))).
• Adding a wildcard symbol may retrieve word variants: (("synchronised swimming") or ((((("synchronize swimming") OR ("synchronism swimming"))) or ("synchronizing swimming"))))*.