Trainer Kristina Earnest is a self-professed lover of all things HIIT and strength, so you know you're in a treat with this quickie workout first seen on Women's Health's weekly lineup of Instagram Live workouts.

Here's everything you need to know:

Time: 20 minutes

Equipment: Dumbbells, towel, mat, water bottle

Good for: Arms & abs

Instructions: You'll start with a warmup and then get right into your sweat session, which will start with two circuits—the first upper body, the second focused on the core. In each circuit, you'll do four exercises for 45 seconds each, two times through. Before you know it, you'll be read for your cool down.

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