It really just depends sometimes. Every woman is different so I think it is crucial to listen to your body.
Typically ovulation is when women are more prone to hurting themselves, and should be used for maybe lighter hypertrophy stuff. luteal phase is more focused on fat loss, and the follicular phase is focused around strength/progression. Menstruation phase should be used for rest and recovery mostly.
I’m not sure what this cardiovascular test involves though. If it’s steady state type of stuff you could probably do okay regardless of whatever phase you’re in (except maybe during menstruation), if it’s HIIT type of stuff, or For speed or endurance, perhaps focus on follicular phase.
Other than that, it’s really a game of just being watchful. Some cycle may be slightly different than others, so just monitor progress and how you feel.