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Is it safe for someone like me who is I would say an intermediate level of strength and endurance to do HIIT 5 days if it is not the same muscle? For instance, if:

Monday- Sprint interval training
Tuesday- HIIT Row or Swimming (maybe some weights,upper body only)
Wednesday- Bike or Stairclimber
Thursday-HIIT Row or swimming (maybe some weights,upper body only))
Friday- Sprint Interval Training
Sat & Sun- off

Not necessarily a set schedule, possibly this:

Monday- Sprints
Tuesday- HIIT Row or Swim, Weights (upper body only)
Wednesday- off
Thursday- Sprints
Friday- HIIT row or swim, weights (upper body only)
Sat- HIIT Bike or stairs
Sun-off

Or is this going to overtrain? I like some upper body HIIT, and I just figure I can do that in between lower body HIIT, or am I just going to overtrain the heck out of my body? Anyone with any advice for me...thanks!

You're not necessarily going to overtrain, but it's unclear if you'll make more gains than if you just did it 3 times a week. Why would you only do upper body weights? You need to do upper and lower.

It's great that you're able to bike, run, swim, and row. You should try HIIT 3 days a week and lifting on two other days, and this also leaves you with two days of rest. I think this would be best, and is at least the proper place to start, and you can always add on more in the future, but I wouldn't recommend doing anything else on your weight lifting days or having less rest.