Coping HIIT circuit workouts and training plans

Hello there!

I’ve been using Trainerroad since 2013 as my main training resource with great success, having achieved this year my PR of around 4.3 W/kg at 40 years of age (side note: I’m probably one of the first guys in Brazil to use Trainerroad).

Now, as I’m getting older, I want to incorporate a once a week HIIT circuit class (10-exercise circuit performed 4 times - 40 seconds for each exercise with 20 second rest) to my routine.

Considering I’m about to start Sweet Spot Base Mid Volume, when is the best day to perform those HIIT circuit classes? On wednesdays?