Perhaps you should try some spelling variations:
"synchronize swimming" » "synchronism swimming", "synchronizing swimming"
"synchronized stemming" » "synchronismd stemming", "synchronizingd stemming"
"synchronized stepping" » "synchronismd stepping", "synchronizingd stepping"
"synchronised stemming" » "synchronism stemming", "synchronising stemming"
"synchronised streaming" » "synchronism streaming", "synchronising streaming"
"synchronised treating" » "synchronism treating", "synchronising treating", "synchronised creating", "synchronised heating", "synchronised relating"

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