The important thing is to not get your heart rate and body temp up too high. Also not to take up any new sport or exercise or up your normal load.
So just don't push yourself too hard. Cycling should be fine, I have always continued to ride my bike if I feel like it during a TWW. My BF continues to ride daily to/from work at 31 weeks!
Definitely keep active especially if that is what you are used to IMO.
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