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