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

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