Holy cow! Last night I took one of the harder strength classes I have ever been to. It's called Pyrolates at Firebrand Sports in Portland, OR. The name actually explains it all. It felt like my entire body was burning most of the time, but in a controlled, Pilates-like fashion that's safe, effective and insanely hard! Normally, I am not a fan of burn until you die workouts, but this class is an exception.
Portlanders, if you're looking for a strength class that gets results, I HIGHLY recommend checking out Firebrand's Pyrolates class. Like most Pilates workouts, this class is especially great for runners because it targets hip stabilizers and abdominals in a way that will seriously benefit your running form and running strenght. Not to mention, a glute, hamstring and quad workout that crushed me the second half of class. Legs and core are happy, but very spent.
When you do show up for your first class, don't be shy about modifications - the instructor in my class was amazing at providing them on both ends of the spectrum. Here's the machine that you use for this class. It reminds me of a reformer on steroids.
A word of caution for any runner: don't plan a hard running workout for the day after one of these classes. You're going to need a recovery run day.