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

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

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