I am on a 3 day split routine (chest and triceps Mondays, back and biceps Wednesdays and shoulders and legs Fridays) with Cardio on Tuesday, Thursday and Sunday.
I am taking some new suppliments (creatine) that have directions to take on “workout days” so I am trying to figure out if cardio days count or just my lifting days.
It all depends on YOUR definition of “workout day”. I usually consider any planned exercise, a workout, so technically a cardio day would be considered a “workout day”.
When it comes to your creatine supplement, saying to take it on your workout days, they’re usually meaning to take it on days you lift weights. Our body naturally creates creatine phosphate, and uses it as our “immediate energy system”. This energy system is used during high-intensity, short duration bouts of exercises, such as: 40-100 meter sprint, first few reps of a power/heavy lift. So taking a creatine supplement will benefit your intense training bouts, and help recovery in between sets. Creatine would help you with your cardio if and only if you were performing HIIT (High Intensity Interval Training), as this type of cardio requires high amounts of effort/energy, and utilizes glycolysis as well as your immediate (creatine phosphate) energy system.
It is determined by intensity, duration and frequency. A vigorous cardiovascular workout (cycling, running, swimming, etc.) certainly counts as a workout. Why are you counting?
And I would also ask why are you taking supplemental creatine? What is your goal? Is it to enhance your power capability? At best, it’s temporary.