For me, heavy double kettlebell drills are very challenging.
I've also gotten my best results from double kettlebell movements weather it's conditioning complexes or some type of strength circuit.
Since I don't have all the time in the world to train, I choose to do circuit style double kettlebell 5x5's, or ladder workouts. This is a very efficient way of training that's gets tones of bang for your buck.
Here's what I had going on today
Double kettlebell front squats 5
Weighted pull ups (20kg's)
Double kettlebell press
Swing set knees to chest 10
Did my first 3 rounds with double 28 kg's and my last 2 with double 32's
I will be mixing up the 5x5's and the ladders and hitting these heavy strength wo's 3x/week
I've been using 25 lbs in the weigted vest for my pull ups, but went with body weight today and went quicker to get a little more conditioning effect. Besides, I was feeling the effects of the 7 mile row yesterday.